general specification - roads and bridges
TRANSCRIPT
Table of contents
1 BRIDGES, OVERPASSES AND VIADUCTS.......................................................11.1 DIRECT FOUNDATIONS....................................................................................................................1
1.1.1 General provisions for direct foundations..............................................................................11.1.2 Construction of shored-up foundations..................................................................................1
1.2 DIRECT DEEP FOUNDATIONS..........................................................................................................11.2.1 Direct deep foundations..........................................................................................................1
1.2.1.1 General provisions...............................................................................................................11.2.1.2 Unforeseen conditions.........................................................................................................2
1.2.2 Large diameter drilled piles....................................................................................................21.2.2.1 Simple drilled piles..............................................................................................................21.2.2.2 Cased drilling pipes.............................................................................................................21.2.2.3 Cast-in-site piles under drilling mud...................................................................................21.2.2.4 Nature, origin and quality of materials...............................................................................21.2.2.5 The piling method statement................................................................................................31.2.2.6 Construction plant...............................................................................................................31.2.2.7 Preliminary works...............................................................................................................41.2.2.8 Pile reinforcement...............................................................................................................41.2.2.9 Pile drilling..........................................................................................................................51.2.2.10 Concreting...........................................................................................................................61.2.2.11 Base injection of piles..........................................................................................................61.2.2.12 Pile head preparation..........................................................................................................61.2.2.13 Quality control during construction....................................................................................71.2.2.14 Acceptance of drilled pipes of large diameter.....................................................................8
1.2.3 Foundation columns................................................................................................................8
1.3 BRIDGE SUBSTRUCTURE, ABUTMENTS, PIERS.............................................................................81.3.1 Construction of piers and abutments......................................................................................81.3.2 Joining the abutment to the earthworks..................................................................................91.3.3 Construction materials............................................................................................................9
1.3.3.1 Manufacturing of post - tensioned reinforcement...............................................................91.3.3.2 Manufacturing of cable channels for post - tensioned reinforcement...............................101.3.3.3 Mounting post - tensioned reinforcement..........................................................................111.3.3.4 Anchorages........................................................................................................................11
1.3.4 Remedial works....................................................................................................................12
1.4 REINFORCED CONCRETE SUPERSTRUCTURE.............................................................................121.4.1 General provisions, formwork, reinforcement......................................................................121.4.2 Temporary works..................................................................................................................131.4.3 Formwork.............................................................................................................................131.4.4 Precast units, erection...........................................................................................................131.4.5 Works acceptance.................................................................................................................14
1.4.5.1 Testing of works.................................................................................................................141.4.5.2 Remedial works..................................................................................................................14
1.5 SCAFFOLDING AND CENTERING...................................................................................................151.5.1 General provisions................................................................................................................151.5.2 Design of temporary works..................................................................................................151.5.3 Construction and use of temporary works............................................................................161.5.4 Construction, use, trials........................................................................................................16
1.6 FORMWORK.....................................................................................................................................161.6.1 General data..........................................................................................................................161.6.2 Supplementary conditions for formwork..............................................................................171.6.3 Preliminary works and acceptance.......................................................................................17
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1.6.4 Formwork erection, treatment during concrete hardening....................................................181.6.4.1 Erection of formwork.........................................................................................................181.6.4.2 Supporting elements of the formwork................................................................................18
1.7 REINFORCEMENT............................................................................................................................181.7.1 Steel for reinforcement.........................................................................................................181.7.2 Delivery and marking...........................................................................................................191.7.3 Quality control......................................................................................................................191.7.4 Bending, erection and fixing of reinforcement.....................................................................191.7.5 Tolerances in erection...........................................................................................................201.7.6 Welded wire reinforcement..................................................................................................201.7.7 Reinforcement repairs...........................................................................................................201.7.8 Spacers..................................................................................................................................201.7.9 Substitution of designed reinforcement................................................................................20
1.8 CONCRETE........................................................................................................................................211.8.1 General specification............................................................................................................211.8.2 Concrete requirements..........................................................................................................22
1.9 PRE-STRESSED CONCRETE BRIDGE SUPERSTRUCTURES..........................................................231.9.1 General specifications...........................................................................................................231.9.2 Formwork, moulds, supports for formwork.........................................................................231.9.3 Reinforcement.......................................................................................................................23
1.9.3.1 General parameters...........................................................................................................231.9.3.2 Handling, transport and storage.......................................................................................24
1.9.4 Demands and performance criteria for concrete...................................................................251.9.5 Construction of the works.....................................................................................................26
1.9.5.1 Concrete binding of precast units......................................................................................261.9.5.2 Stressing and anchorage blocking.....................................................................................261.9.5.3 Grouting of the cables.......................................................................................................27
1.9.6 Quality control, works acceptance........................................................................................27
1.10 ACCESSORIES...................................................................................................................................271.10.1 Bearings................................................................................................................................271.10.2 Water outlet devices.............................................................................................................281.10.3 Railings.................................................................................................................................281.10.4 Kerbs for footpaths...............................................................................................................281.10.5 Ant seismic devices..............................................................................................................28
1.11 WATERPROOFING AND EXPANSION JOINTS................................................................................281.11.1 Waterproofing.......................................................................................................................28
1.11.1.1 General provisions.............................................................................................................281.11.1.2 Technical specification......................................................................................................291.11.1.3 Prescriptions for construction...........................................................................................30
1.11.2 Covering expansion joints....................................................................................................311.11.2.1 General..............................................................................................................................311.11.2.2 Technical features..............................................................................................................321.11.2.3 Prescriptions......................................................................................................................33
1.12 BRIDGE DECK PAVEMENT.............................................................................................................341.12.1 General provisions................................................................................................................341.12.2 Technical conditions.............................................................................................................35
1.12.2.1 Geometrical data...............................................................................................................351.12.2.2 Tolerances..........................................................................................................................36
1.12.3 Materials...............................................................................................................................361.12.4 Priming.................................................................................................................................371.12.5 Works control and acceptance..............................................................................................38
1.13 REVETMENT AND STONE MASONRY...........................................................................................381.13.1 General provisions................................................................................................................381.13.2 Construction of rubble stone masonry..................................................................................38
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1.13.3 Hewn stone masonry.............................................................................................................391.13.4 Control and acceptance of stone masonry............................................................................39
1.14 GUNITING.........................................................................................................................................391.14.1 Materials used for guniting...................................................................................................39
1.14.1.1 Cement...............................................................................................................................391.14.1.2 Aggregates.........................................................................................................................401.14.1.3 Additives............................................................................................................................40
1.14.2 Mortar and concrete guniting................................................................................................401.14.3 Mortar and concrete applied by guniting..............................................................................411.14.4 The supporting surface.........................................................................................................411.14.5 Application of mortar and concrete by guniting...................................................................421.14.6 Surface treatment of gunite...................................................................................................431.14.7 Checking of guniting works..................................................................................................43
1.15 REPAIR OF DAMAGED CONCRETE................................................................................................431.15.1 Concrete................................................................................................................................431.15.2 Mortars..................................................................................................................................44
1.16 COATING REPAIRS...........................................................................................................................44
2 ROADS.....................................................................................................................452.1 EARTHWORKS.................................................................................................................................45
2.1.1 General provisions................................................................................................................452.1.2 Materials...............................................................................................................................46
2.1.2.1 Top Soil..............................................................................................................................462.1.2.2 Soils for earthworks...........................................................................................................462.1.2.3 Water..................................................................................................................................462.1.2.4 Quality control of soils......................................................................................................46
2.1.3 Earthworks construction.......................................................................................................502.1.3.1 Setting out..........................................................................................................................502.1.3.2 Preliminary works.............................................................................................................502.1.3.3 Displacement of Earthworks..............................................................................................512.1.3.4 Borrow pits and earth stockpiles.......................................................................................512.1.3.5 Cuttings..............................................................................................................................522.1.3.6 Preparation of the soil under embankment.......................................................................542.1.3.7 Construction of the embankment.......................................................................................542.1.3.8 Ditches and Gutters...........................................................................................................572.1.3.9 Roadbed finishing..............................................................................................................572.1.3.10 Protection with top soil......................................................................................................57
2.1.4 Control of construction and acceptance of works.................................................................572.1.4.1 Control of Construction.....................................................................................................572.1.4.2 Acceptance of Works..........................................................................................................60
2.2 LAYER OF BALLAST OR OPTIMAL BALLAST MIXTURE.............................................................602.2.1 General provisions................................................................................................................602.2.2 Materials...............................................................................................................................61
2.2.2.1 Natural aggregates............................................................................................................612.2.2.2 Water..................................................................................................................................63
2.2.3 PREPARATION OF OPTIMAL BALLAST.......................................................................632.2.3.1 Optimal ballast preparation plant.....................................................................................632.2.3.2 Preparation of the mixture.................................................................................................642.2.3.3 Quality control of the mixture............................................................................................64
2.2.4 CONSTRUCTION OF THE FOUNDATION COURSE.....................................................642.2.4.1 Trial section.......................................................................................................................642.2.4.2 Preliminary conditions......................................................................................................652.2.4.3 Transport...........................................................................................................................652.2.4.4 Construction......................................................................................................................65
2.2.5 Control and acceptance of the works....................................................................................662.2.5.1 Verifying the horizontal geometry.....................................................................................67
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2.2.5.2 Verifying the compaction and the bearing capacity..........................................................672.2.5.3 Verifying the characteristics of the course surface...........................................................672.2.5.4 Acceptance on execution stages.........................................................................................68
2.3 CRUSHED STONE OR CRUSHED STONE OPTIMAL MIXTURE COURSE.....................................682.3.1 General provisions................................................................................................................682.3.2 MATERIALS.......................................................................................................................69
2.3.2.1 Natural aggregates............................................................................................................692.3.2.2 Water..................................................................................................................................722.3.2.3 Geo-textile Material...........................................................................................................722.3.2.4 Quality control of aggregates............................................................................................72
2.3.3 Construction of the foundation course..................................................................................722.3.3.1 Establishing the compaction characteristics.....................................................................722.3.3.2 Trial section.......................................................................................................................732.3.3.3 Preliminary conditions......................................................................................................742.3.3.4 Construction......................................................................................................................74
2.3.4 Control of construction and acceptance of works.................................................................752.3.4.1 Verifying the horizontal geometry.....................................................................................752.3.4.2 Verifying the compaction and the bearing capacity..........................................................762.3.4.3 Verifying the characteristics of the surface of the layer....................................................762.3.4.4 Acceptance of works on construction stages.....................................................................76
2.4 BASE COURSE OF HOT ROLLED ASPHALT MIXTURES...............................................................762.4.1 General provisions................................................................................................................762.4.2 Materials...............................................................................................................................78
2.4.2.1 Natural aggregates............................................................................................................782.4.2.2 Filler..................................................................................................................................782.4.2.3 Bitumen..............................................................................................................................792.4.2.4 Bituminous emulsion..........................................................................................................792.4.2.5 Additives............................................................................................................................79
2.4.3 Asphalt mixture preparation.................................................................................................802.4.3.1 Establishing the composition.............................................................................................802.4.3.2 Asphalt mixing plant..........................................................................................................83
2.4.4 Asphalt laying.......................................................................................................................842.4.4.1 Trial section.......................................................................................................................842.4.4.2 Preparation of support layer.............................................................................................842.4.4.3 Transport...........................................................................................................................852.4.4.4 Execution...........................................................................................................................85
2.4.5 Control of execution and acceptance of works.....................................................................852.4.5.1 Quality control of materials...............................................................................................852.4.5.2 Control of preparation and laying the mixture..................................................................862.4.5.3 Quality control of the executed layer.................................................................................872.4.5.4 Acceptance of works..........................................................................................................88
2.5 BITUMINOUS SURFACES................................................................................................................882.5.1 General provisions................................................................................................................882.5.2 Materials...............................................................................................................................89
2.5.2.1 Natural aggregates............................................................................................................892.5.2.2 Filler..................................................................................................................................892.5.2.3 Bitumen..............................................................................................................................902.5.2.4 Bituminous emulsion..........................................................................................................912.5.2.5 Fibres.................................................................................................................................91
2.5.3 Establishing the job mix composition...................................................................................912.5.3.1 Cellulose fibres content in the asphalt mixtures................................................................952.5.3.2 Filler/bitumen ratio...........................................................................................................95
2.5.4 Physical – mechanical characteristics...................................................................................962.5.4.1 Physical-mechanical characteristics of the asphalt mixtures stabilized with fibres.........972.5.4.2 Determination of the physical-mechanical characteristics...............................................982.5.4.3 Characteristics of the bituminous surface layers..............................................................982.5.4.4 Characteristics for the surface of the executed layer........................................................99
2.5.5 Preparation and laying of the asphalt mixtures...................................................................101
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2.5.5.1 Preparation of the asphalt mixtures................................................................................1012.5.5.2 Installation for preparing the asphalt mixture................................................................1022.5.5.3 Laying the asphalt mixture..............................................................................................104
2.5.6 Control of the execution and acceptance of works.............................................................1062.5.6.1 Verification of the geometrical elements.........................................................................1062.5.6.2 Characteristics of the bituminous surface.......................................................................1062.5.6.3 Acceptance of works........................................................................................................106
ANNEX A...................................................................................................................................................107
ANNEX B - TYPES OF MIXTURES FOR THE WEARING COURSE..........................................................108
ANNEX C - TYPES OF MIXTURES FOR THE WEARING COURSE..........................................................109
ANNEX D - THE REFERENCES FOR DIFFERENT TYPES OF THE ASPHALT MIXTURES PROVIDED FOR THE EXECUTION OF THE HOT ROLLED BITUMINOUS SURFACES...................................110
2.6 ROAD MARKING............................................................................................................................1102.6.1 General provisions..............................................................................................................1102.6.2 Materials.............................................................................................................................111
2.6.2.1 Technical conditions regarding marking.........................................................................1112.6.2.2 Quality control of the paint for road marking.................................................................111
2.6.3 Types of road marking........................................................................................................1112.6.3.1 Longitudinal marking......................................................................................................1112.6.3.2 Transverse marking.........................................................................................................1122.6.3.3 Other marking..................................................................................................................112
2.6.4 Execution of the road marking...........................................................................................1132.6.5 Control of execution and acceptance of works...................................................................114
ANNEX 1....................................................................................................................................................115
ANNEX 2....................................................................................................................................................117
2.7 ROAD SIGNING...............................................................................................................................1182.7.1 General provisions..............................................................................................................1182.7.2 Types of signs, sizes...........................................................................................................118
2.7.2.1 Type of Signs....................................................................................................................1182.7.2.2 Size of the signs................................................................................................................119
2.7.3 Manufacture the signs.........................................................................................................1192.7.4 Manufacture and painting the poles....................................................................................1202.7.5 Control of execution and acceptance of works...................................................................120
2.7.5.1 Photometrical analysis....................................................................................................1212.7.5.2 Mechanical characteristics..............................................................................................1242.7.5.3 Verifying the resistance against environment agents......................................................1242.7.5.4 Control of the execution of the panels.............................................................................1252.7.5.5 Acceptance of works........................................................................................................125
2.8 CULVERTS......................................................................................................................................1252.8.1 General................................................................................................................................1252.8.2 Description of operations....................................................................................................126
2.8.2.1 The Work Area Execution................................................................................................1262.8.2.2 Excavation and Support of Excavation............................................................................1262.8.2.3 Foundation construction..................................................................................................1272.8.2.4 Wall and slab construction..............................................................................................1272.8.2.5 Pre-cast unit walls and slabs...........................................................................................1282.8.2.6 Execution of the drain behind the abutments and the pre-cast elements........................1282.8.2.7 Monolith headwalls.........................................................................................................128
2.8.3 Materials – quality requirements........................................................................................1282.8.3.1 Water................................................................................................................................1282.8.3.2 Cement.............................................................................................................................1282.8.3.3 Aggregates.......................................................................................................................1292.8.3.4 Shutters............................................................................................................................1292.8.3.5 Rubble stone.....................................................................................................................1292.8.3.6 Concrete...........................................................................................................................129
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2.8.3.7 Reinforcement..................................................................................................................1292.8.3.8 Quality Checking.............................................................................................................129
2.9 CONSOLIDATION WORKS.............................................................................................................1312.9.1 Slope protection..................................................................................................................131
2.9.1.1 General data....................................................................................................................1312.9.1.2 Slope protection of the surface with geogrids.................................................................1312.9.1.3 Slope protection of the surface with geo-cells.................................................................1312.9.1.4 Materials – quality requirements.....................................................................................1322.9.1.5 Quality checking..............................................................................................................132
2.9.2 Reinforced soil embankment walls.....................................................................................1332.9.2.1 General data....................................................................................................................1332.9.2.2 Description of operations................................................................................................1332.9.2.3 Materials - Quality specifications...................................................................................1342.9.2.4 Quality checking..............................................................................................................135
2.9.3 Concrete retaining walls.....................................................................................................1362.9.3.1 General data....................................................................................................................1362.9.3.2 Description of operations................................................................................................1362.9.3.3 Materials - Quality requirements....................................................................................1372.9.3.4 Quality checking..............................................................................................................138
2.9.4 Precast cantilevers..............................................................................................................1402.9.4.1 General data....................................................................................................................1402.9.4.2 Description of operations................................................................................................1402.9.4.3 Materials - Quality requirements....................................................................................1412.9.4.4 Quality checking..............................................................................................................141
2.9.5 Anchors...............................................................................................................................1422.9.5.1 General data....................................................................................................................1422.9.5.2 Description of operations................................................................................................1432.9.5.3 Quality checking..............................................................................................................144
2.9.6 Drilled pile retaining walls.................................................................................................1452.9.6.1 General............................................................................................................................1452.9.6.2 Description of operations................................................................................................1452.9.6.3 Materials – quality conditions.........................................................................................1472.9.6.4 Quality check...................................................................................................................148
2.9.7 Drainage using drilled columns filled with ballast.............................................................1502.9.7.1 General............................................................................................................................1502.9.7.2 Description of operations................................................................................................1502.9.7.3 Materials – quality conditions.........................................................................................1512.9.7.4 Quality check...................................................................................................................151
2.9.8 Sub soil drainage.................................................................................................................1512.9.8.1 General data....................................................................................................................1512.9.8.2 Description of operations................................................................................................1522.9.8.3 Materials to be used - quality requirements....................................................................1542.9.8.4 Quality control.................................................................................................................1552.9.8.5 Gabions and Rockfill Mattresses.....................................................................................1562.9.8.6 Anchored Wire Nets........................................................................................................156
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1 BRIDGES, OVERPASSES AND VIADUCTS
1.1 DIRECT FOUNDATIONS
1.1.1 General provisions for direct foundations
Direct foundation of bridges, and overpasses, comprise:
in sites shored-up by means of wooden sheet piling, metal poling boards, steel sheeting;
by means of open caisson.
Construction of surface foundations in special conditions are detailed in the special specifications.
For foundations requiring working in compressed air, the Contractor shall submit construction method statements to the Engineer for approval.
1.1.2 Construction of shored-up foundations
The Contractor shall submit construction method statements for the Engineer’s approval.
The documentation shall include:
site dimensioning, conditions for the construction, procedure of digging in the site, position of the site, control of possible horizontal displacement;
steps to avoid the deformability of the site during the digging;
concrete composition and parameters;
the procedure of concreting inside the over all the height of the foundation.
Before the start of excavation the Contractor shall check the layout, dimensions, tolerances and also the operating of equipment.
The Contractor shall seek the Engineer’s approval prior to the start of concrete works.
If the concrete is to be poured under water, this shall be by means of tremie-pipes.
1.2 DIRECT DEEP FOUNDATIONS
1.2.1 Direct deep foundations
1.2.1.1 General provisions
The provisions for direct deep foundations of bridges and grade separation structures may apply also to retaining walls or road consolidation works.
Deep foundations means the works between the bottom of the raft and the foundation level.
The present section contains the technical specification for the construction of following type of foundation:
drilled piles of large diameter;
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column foundation;
drilled piers;
driven precast piles.
1.2.1.2 Unforeseen conditions
If unforeseeable geotechnical or hydro geological conditions are met during the works that require a radical change of work procedure, the contractor may propose to the Engineer alternative working methods. The decision of the Engineer will be in writing.
1.2.2 Large diameter drilled piles
Piles are placed in a number of ways depending upon their size.
1.2.2.1 Simple drilled piles
Simple drilled piles shall be performed by casting the concrete by means of a tremie in a drilling with unshored walls. This procedure may be used only in stable soils, without underground water.
1.2.2.2 Cased drilling pipes
The concrete shall be poured by means of a tremie pipe, in a cased drilling.
The casing may be temporary or permanent and may be introduced by vibration, ramming or pressing (with or without twisting).
Columns are foundation elements of the same category, being composed of reinforced concrete or steel tubes, introduced in the ground by vibrating, with the inside soil removed.
1.2.2.3 Cast-in-site piles under drilling mud
The concrete is poured by means of a tremie pipe in the drilling shored by drilling mud (for instance bentonite slurry).
1.2.2.4 Nature, origin and quality of materials
Concrete
The concrete of the drilled piles shall be at least C 20/25 (Bc 25).
For piles in soils with aggressive water, the composition of the concrete shall observe the provisions of SR 3011/96 and STAS 3349/1,2-83.
The use of workability agents to increase the concrete workability, and or retarding admixture if necessary, is allowed.
The consistency of the concrete by the slump test must be:
10 -15 cm for concrete poured in dry medium;
15 - 18 cm concrete poured under water or under bentonite slurry.
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1.2.2.5 The piling method statement
The piling method statement shall include at least the following data:
number (item) of identification;
dimension of the cross section, reinforcement composition, item of the reinforcement (or carcass);
inclination and orientation;
pile’s foot level;
working platform level;
pile’s head concreting level;
length of the restraining zone in the pile foundation raft;
the succession order for the construction of the drillings or for casing driving.
The distance between the axes of two piles shall be at least 2d+2 x 0.015l, where “d” is the pile’s diameter and “l” the actual length in soil.
Tolerances
The limit tolerance for the plan position at the raft foundation interior level is:
- 7.5 cm for piles in a single row
- 10 cm for piles in several rows.
The limit tolerance for batter of the pile’s axis is 2%.
The limit tolerance for dimensions:
- diameter - 2 cm;
- pile’s foot level 20 cm;
- pile’s head level 5 cm.
1.2.2.6 Construction plant
The Contractor shall obtain the Engineer’s approval for construction plant and equipment. This shall take account of the pile lay out, geological, geotechnical and hydro geological features, and take account of the necessary protection of near-by buildings or existing constructions.
Contractor’s proposals shall emphasize:
type of the driving or drilling equipment;
preparation for drilling;
equipment for control of concreting (including pouring at the pile’s base);
connection details between the sections of the unrecoverable casing.
Foot flaring of the piles is allowed only if they penetrate a stratum high cohesive of a compression strength with lateral deformation of min. 300 KPa.
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The flaring may have the shape of a cone frustum; with the height equal at least to the diameter of the current cross section, and the base area at most three times the area of the current cross section.
1.2.2.7 Preliminary works
The working platforms shall be arranged for the easy access, circulation and operation of the construction plant in proper conditions of quality and safety.
Possible necessary works for site consolidation, unforeseen by the design, shall be performed only with the Engineer’s approval, which is necessary also for the nature and quality of the materials.
1.2.2.8 Pile reinforcement
Unless otherwise detailed pile reinforcement shall be as follows.
The piles shall be reinforced by means of reinforcement cases composed of longitudinal bars, spiral reinforcement, rigidity rings and spacers.
The reinforcing cage may have constant or variable cross section area along the pile, as a result of the structural analysis.
The longitudinal bars shall be of min 14 mm diameters, at least 8 pieces for a cage, and the free distance between the bars shall be min. 10 cm and max. 35 cm.
The arrangement of the bars on two rows shall be avoided, excepting the piles with heavy strain.
Longitudinal bars shall be welded every 3-4 m, along the cage.
The transverse reinforcement shall be a spiral of minimum 8 mm diameter, but at least 0.4 of longitudinal bars diameter. The pitch of the spiral shall be not bigger than 35 cm or 15 times the diameter of the long bars.
At the top of the cage and in zones of section’s connection, the pitch of the spiral shall be maximum 15 cm a length equal to the pile’s diameter.
If the length of the piles requires the construction of the reinforcing cage of several sections, their connections shall be in accordance with STAS 10107/0-90.
Taking in account that the connections are made on site, the interior cage shall be fixed by supporting devices during the jointing.
The cage shall not rest on the bottom of the drilling and steps must be taken to avoid its displacement during concreting.
The spiral reinforcement may be fixed on the long bars, and the long bars on the rigidity rings, by spot welding.
The Engineer must approve the chosen technology.
For the centering of the cage in the drilled hole, spacers shall be fixed on the exterior of the long bars; these spacers may be sliders (skates) of round steel bar or concrete rollers, 4 pieces in cross section, every 3 - 4 m along the cage.
The thickness of the cover shall be at least:
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4 cm for pile with uncovered casing;
6 cm for piles with recovered casing and for piles without casing (drilled in dry medium);
8 cm for piles drilled under mud protection.
1.2.2.9 Pile drilling
Drilling without casing
Drilling without casing or mud protection will be permitted only in cohesive soils and above the underground water level.
In this case, the concreting must follow the drilling as soon as possible (maximum duration of interruption being 24 hours. The walls of the drilling shall be protected by steel tubes at least 1.5 m below ground.
Drilling under water in recoverable casing
This solution may be applied in any soil condition, with equipment adapted to the nature of the soil strata. The foot of the casing shall be provided with a toothed crown.
If the drilling is performed under water in sand/low cohesive soils soil scouring may occur at the pile’s base, causing loosening of the soil and decrease of the bearing capacity of near-by piles or existing foundations. To avoid such risks, following steps shall be taken:
sinking the casing by mean of water jet under pressure shall be avoided;
excavation by suction shall be avoided;
the base of the casing shall be kept deeper than the bottom of the drilling by at least half the diameter of the drilled hole (advanced casing);
the water level inside the drilling shall be always kept 1 m above the hydrostatic level;
the speed of the excavation shall be moderate and the grab bucket shall be raised smoothly.
Concreting shall begin maximum 36 hours after finishing the drilling.
Drilling under mud
The drilling’s walls shall be protected by a drilling mud (bentonite slurry) prepared according to STAS 2561/4-90.
Drilling under mud of a pile spaced less than 3m from the wall of a near-by pile shall start only after the concrete has set in that pile.
The level of the mud shall be always kept at least 1 m above the hydrostatic level.
The top of the drilling’s walls shall be protected by steel pipes at least 1.5 m deep where required by the Engineer.
Concreting shall begin not later than 8 hours after completion of the drilling.
Drilling under water with unrecoverable casing
Casings shall be of reinforced concrete or metallic cylindrical sections, introduced in the ground by driving, vibrations, pressing and/or twisting. The sections shall be assembled in step with the sinking. The
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earth inside the drilling shall be dug by means of tools adapted to the soil’s nature. The two operations: the casing sinking and drilling, shall be correlated step by step until the foundation level is reached.
Drilling under the casing’s base level (advanced drilling) is only allowed in hard clay or compact rocks.
Cleansing of the pile base
Cleansing of the base is compulsory for any drilling’s procedure and it shall be done before the introduction of the reinforcement cage and the concreting.
In the case of drilling under mud, the base shall be cleansed at most 3 hours before concreting.
It is forbidden to cleanse the base by mud circulation in sand or loose soils (with Mammoth pumps).
1.2.2.10 Concreting
Concreting of the uncasing hole drilling in dry medium
Concreting shall be performed by means of a funnel centered on the axis of the pile, and of a concrete chute lowered in the hole and raised in step with the concreting.
Concreting may also be made using a concrete pump with the hose lowered in the hole.
Concreting under water or mud
Concreting shall be performed by means of tremie pipe, where approved by the Engineer, to avoid contact between water and mud with concrete.
The diameter of the tremie pipe depends on the aggregate size and the pile’s diameter, but shall not be less than 20 cm.
Concreting under water or mud shall be managed as a continuous operation, performed in a single stage. The flow of the concrete depends on the diameter and length of the pile but shall not be less than 4m 3/h. The first batch must ensure the separation of concrete from water or mud and the priming of the tremie.
The base of the tremie shall be between 2 m and 4 m below the concrete level.
1.2.2.11 Base injection of piles
Depending on the base soil nature, and in order to increase the bearing capacity, the base of the pile may be injected with a suspension (cement grout usually) by means of injecting pipes embedded in the pile’s body and having been lowered together with the reinforcement in the drilled hole.
The composition of the suspension, the technology and the injection pressure shall be detailed for every each specified occurrence, depending on the nature of the foundation soil.
1.2.2.12 Pile head preparation
The upper portion of a pile shall be always concreted to a higher level than the final one, as follows:
For dry drilled piles, the supplementary height of concrete is at least 0.5d but no less than 0.5m for piles max. 20 m long and least 0.75 m for piles longer than 20 m (being the diameter of the pile);
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For piles drilled under water or mud the supplementary height of concrete shall be at least 1d but no less than 1m for piles up to 20m long and at least 1.5d but no less than 1.5m for piles more than 20m long.
After hardening, the entire portion of the concrete found inadequate shall be removed and completion shall be made if necessary to ensure the minimum height in the pile foundation required by the Contract and in accordance with STAS 2561/4 - 90.
1.2.2.13 Quality control during construction
Quality control on construction time
Quality control shall be made at every stage of pile construction, according the provisions of STAS 2561/4 - 90.
In case of drilling under mud, the Contractor shall frequently check the quality of the drilling mud by samples taken from the batch plant and directly from the drilling.
If mud from the drilling is inadequate, it shall be replaced to meet the standard parameters.
For concrete works the following tests shall be performed:
for every 10 m3 of placed concrete, samples shall be taken from the casting site and the concrete consistency tested by the slump test, in accordance with STAS 1759/88;
for every 20 m3 of concrete, and at least once for every pile, 3 samples shall be taken for the concrete strength test, according to STAS 1275/88;
for each pile, records shall be taken showing the concrete consumption all along the pile. If abnormal consumption occurs (above or below the calculated volume by more than 30%), the Contractor shall propose steps shall be taken and these shall be approved by the Engineer.
Quality control after construction
Quality control of the piles may include: checking of the plan and batter of the piles, quality checking of the concrete in the head of the pile, checking the continuity of the pile’s body, and control tests on piles.
The quality control of the cast concrete shall be done as follows:
failures to reach the prescribed class of concrete;
deficiencies occurring during concreting;
changes in design reached by agreement between engineer and contractor.
The control may be made:
by uncovering the piles;
by coring (after uncovering or by core drilling);
by non-destructive examination.
The checking of the pile’s body continuity may be done by:
core drilling on all the length of the pile. The procedure requires special equipment and shall be used only for piles where the data from the drilling-concreting report or other observations put in doubt the continuity of the pile;
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non destructive examination (sonic sounding, radioactive sounding, mechanical impedance).
1.2.2.14 Acceptance of drilled pipes of large diameter
Drilled holes will only be accepted by the Engineer after checking the plan and batter of piles, the examination of the foundation ground, and compliance with the data of the geotechnical study.
Pile will only be accepted after examination of the data concerning concreting and of quality control reports.
The following documents shall be presented to the Engineer by the Contractor:
the drilling-concreting report of every pile;
the foundation works register.
1.2.3 Foundation columns
Columns are cast in situ-drilled piles with unrecoverable casings.
Reinforced concrete columns shall be pipes 1 to 2.5 m diameter; with walls 10 - 14 cm thick, in sections 6 - 10 m long.
Pipes may be cast on site or in Contractor’s pre cast plant, by pouring the concrete in vertical moulds. The reinforcement must be able to support the strain resulted from the driving and the service strain. The sections are usually joined by screwed flanges.
Steel pipes shall be helically welded steel pipes or shells of steel plate. The diameter of the steel pipes shall be 1 to 3 m with walls 10 - 30 mm thick.
Jointing of the sections shall be by welding, in step with the sinking.
Construction and acceptance of the columns shall observe the conditions as described previously.
1.3 BRIDGE SUBSTRUCTURE, ABUTMENTS, PIERS
1.3.1 Construction of piers and abutments
The Contractor shall monitor the adequacy of the ground and notify the Engineer of any inadequacy or reason to modify the design.
The Contractor shall set out the foundation before starting construction and obtain the Engineer’s approval to start the works.
After completion of the foundations, the Contractor shall carry out a new survey and report deviations, if any, from the initial setting out. The contractor must submit for the Engineer's approval the necessary remedial measures.
Measurements shall be made also after the completion of the elevations, with the purpose of establishing accurately the length of the superstructure.
Remedial works shall only be performed with the approval of the engineer.
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1.3.2 Joining the abutment to the earthworks
Embankments shall have maximum slope 1:1 and they shall be protected by rubble stone or slab pitching. The pitching must have a foundation deeper than the frost depth.
In the case of buried abutments, the pitching of the embankments shall be continued under the bridge.
To avoid water infiltrations the joints of the pitching shall be jointed with pointing mortar or shall be sealed with bituminous mastic.
1.3.3 Construction materials
1.3.3.1 Manufacturing of post - tensioned reinforcement
When cutting wires, strands or bars to manufacture post - tensioned reinforcement, tools and devices shall be used which do not affect the strand ends or to cause damage when introducing reinforcement into the channels.
The steel shall not be contaminated with earth, grease, oils, and must not be bent during cutting and manufacturing.
At the fixing point where the wires fit in anchorages before pre tensioning, the removal of the temporary protection is necessary.
At the other types of fixing point, temporary protection will be kept only if it’s necessary due to the corrosive environment. The wires shall also be degreased in the anchorage fixing zone.
Individual fixing points and strands are manufactured in specialized pre stressed concrete workshops or in approved temporary on-site workshops.
The set up of the workshops will depend on the production medium capacity and on the fixing point/ type that is to be manufactured.
The individual fixing points and strands manufactured in central workshops shall be accompanied at delivery by a quality certificate which shall contain the number of the quality certificate of the wires used for the fixing points manufacturing and the number of the quality certificate of the strand.
The cutting length of the wires composing the fixing points of the type in Annex 4 of the Practice Code NE 012/99 Part B shall be determined by adding the minimum length shown at points 25 and 26 of the table in the annex, at the length of the fixing points measured between the anchorage seating. If cutting is to be done by a welder a minimum 30 mm shall be added.
Assembling of the wires under the form of fixing point shall be made by smooth wire bunches of 1.5 mm in diameter, at ends and at about 200 mm spacing. Intermediary wire bunches may be eliminated or reduced in number by helicoidally spinning the fixing points with a pitch of about 250 mm. All the wire bunches shall have the ends bent inside the fixing points to allow enter into cases.
For fixing points of other types apart those in annex 4 of the Practice Code NE 012/99 Part B, refer to the special specification.
For haulage and storage, the fixing points not introduced in cases shall be wound with manual or mechanical devices (annex 5 of the Practice Code NE 012/99). The rolling diameter shall be minimum 2100 mm for the fixing points made of 5 mm diameter wire and minimum 2300 mm for the fixing points made of 7 mm diameter wire.
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Fixing points introduced in polyethylene tubes may also be used, in this case the rolling diameter shall be determined by the tube rigidity and by the number of wires in the fixing point, being determined by trials.
1.3.3.2 Manufacturing of cable channels for post - tensioned reinforcement
Cable channels for post - tensioned reinforcement shall be according to the Contract. For the methods shown in Annex 4, the channels (lined or not) shall be according to the data in Annex 4 and 6 of the Practice Code NE 012/99 Part B.
Cable channels and cases shall fulfil the following:
assurance of the curvature radius in conformity with the design;
sheet thickness shall be 0.2 mm for to 0.6 mm;
the ratio between the cable channel and the fixing points diameters shall permit the introducing of the pre tensioned reinforcement and injection in good conditions of the cement grout; the inner diameter of the case should be 10mm greater than that of the fixing point and the inner section area of the case will be at least twice that of the reinforcement;
assurance of achieving a good connection at the ends;
assurance of waterproof interior;
marking, packing, handling, transport and storage in good conditions.
Plastic cases may be used only for elements, whose fatigue is not calculated and on the condition that the working temperature isn't higher than +40ºC. Heat treatment shall not be used for concrete hardening.
Changes to the type of channel shall only be done with the Engineer's consent.
High transverse rigidity cases shall be used where approved by the Engineer.
Injection or ventilation couplings (T-square) shall be positioned in conformity with section 8 of the Practice Code NE 012/99 Part B and shall be connected to cases that line the cable channel so as not to reduce the inner diameter.
Unless otherwise specified the tolerances for case positioning shall be:
height of the element:
- for height up to 200 mm*. 0.02 h
- for height between 200 and 1000 mm. 5 mm
- for height more than 1000 mm. 10 mm
width of the element:
- for width up to 200 mm*. 5 mm
- for width between 200 and 1000 mm. 10 mm
- for width more than 1000 mm. 20 mm
* At the end of the element, these tolerances shall be zero.
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Where cable channels are from sections that are to be joined, deviations at the ends due to a joint shall not exceed ± 3 mm on the line of the same channel.
Positioning devices for the cases shall be assembled and positioned to the approval of the engineer.
Positioning devices shall prevent the displacement of the case - fixing point assembly during concreting.
In the end zones, the axis of the cable channels shall be perpendicular to the supporting surface of the anchorages.
1.3.3.3 Mounting post - tensioned reinforcement
Where lined cable, channels with sheet cases or plastic, the fixing points shall be mounted before concreting improving the longitudinal and transversal rigidity of the cases.
In cold or wet weather other methods for improving the case rigidity (steel bars or tubes, plastic tubes with smaller diameter), shall be adopted with the fixing points being introduced afterwards.
The advancing end of the fixing point shall be provided with a cone anchored by the fixing point wires.
Before closing the formwork a check and a report on hidden works shall be made as follows:
Deviations from design;
Case faults (holing, cracks, unwinding);
Connections for injection and ventilation.
Before start of the pre tensioning and injecting operations, in order to prevent the water penetration in channels and corrosion, ends of the fixing points shall be protected (with bitumen, board, plastic cases).
1.3.3.4 Anchorages
Anchorages for part - tensioned reinforcement and the blocks for pre-tensioned reinforcement shall have the strength at least equal to the yield point of the pre-tensioned reinforcement without significant deformations of the component parts.
Fixing point anchoring in annex 4 shall be made with the anchorages shown in annex 7 of the Practice Code NE 012/99 Part B.
Anchorages with loop and top (annex 7 - fig. 7.6 of the Practice Code NE 012/99 Part B) shall not be used in places subject to fatigue.
Anchorages with loop and top shall be installed in special grooves filled with concrete or mortar for protection prior to concrete being poured.
Pre-tensioned reinforcement anchorages shall be from approved purpose built blocks.
Where individual strands are used, post - tensioned corrosion resistant reinforcement anchorages (blocks) shall be used.
Anchorages for end fixing of SNP Ø7 mm band shall fulfill the following acceptance conditions:
diameter 10.6 ± 0.3 mm
height 7 ± 0.3 mm
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eccentricity max. 0.3 mm
open fissures max. 1.5 mm
maximum 2 fissures more than 30º to the axis.
no fissures inclined at more than 60º to the axis.
A maximum of 5% of the total number of bulbs not fulfilling theses conditions is acceptable.
Alternative anchorage systems may be proposed by the Contractor for the Engineer’s approval.
Anchorage materials shall be handled and stored, in good conditions avoiding corrosion or damage.
1.3.4 Remedial works
After a survey and analysis of defects the Contractor shall submit for the approval of the Engineer a program of repairs.
Remedial works shall be at the Contractor's cost.
For defects affecting the quality of the structure, the safety and durability in service, proceed as follows:
a detailed survey of the defects shall be prepared;
causes shall be investigated and supplementary tests, investigations and analysis shall be done where required;
the short and long term consequences shall be estimated;
a repair file shall be prepared.
Depending on the findings and on the conclusions of the study, the Engineer may proceed as follows:
to approve the repairs, with possible observations;
to order the demolition of the whole or part of the works.
For defects concerning the geometry of the construction, the quality or the colour of the surfaces, but not affecting the safety and the bearing capacity of the construction, remedial works shall be to the Engineer’s approval.
On visible surfaces with fine facing repair with simple cement wash is forbidden.
Open cracks, which may compromise the durability and the aspect of the works must be sealed by injection and cleansed afterward with compressed air.
1.4 REINFORCED CONCRETE SUPERSTRUCTURE
1.4.1 General provisions, formwork, reinforcement
This section covers reinforced concrete works or parts or works of the bridge superstructures; namely:
reinforced concrete beams - on two supports or continuous;
reinforced concrete slabs, cast in place;
reinforced concrete frame structures, arches and vaults;
precast units (carriage-way slabs, footpath slabs, railings, slabs for superstructures);
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concrete (in-situ) binding of precast units.
If the structure is also pre-stressed, the relevant provisions shall be observed.
Precast units may only be used in superstructures if accompanied by quality certificates.
Construction of bridge superstructures of reinforced concrete shall observe the provisions of the Practice Code concerning the construction of concrete, reinforced concrete and pre-stressed concrete works - NE 012/99, and Code of practice for construction of concrete, reinforced concrete and pre-stressed concrete precast units NE 013/02.
1.4.2 Temporary works
Bridge superstructures of reinforced concrete are performed by the help of temporary works, namely:
scaffolding and shoring for girders and straight plates;
scaffolding and shoring for arches and vaults.
The Contractor shall design of the temporary works. The design contains working drawings and calculations. The temporary works shall be performed in such a way as to guarantee the strength, shape and aspect of the final works.
The temporary works shall assure that the final works comply, regarding the tolerances, with those admitted in Annex no. 1 of the Practice Code concerning the construction of concrete, reinforced concrete and pre-stressed concrete works - NE 012/99.
1.4.3 Formwork
Formwork for the reinforced concrete superstructure shall observe the quality conditions provided in the drawings. The quality types are:
ordinary formwork for unseen surfaces;
fair faced exposed;
formwork for face concrete (girders, slabs, arch’s, vaults, pillars);
special formworks for special finishing for marginal beams, sidewalk cornice, railing parapet, etc.
The Contractor may propose his own procedure for the construction of the facing concrete, with the agreement of the Engineer.
Formwork for reinforced concrete superstructures shall comply with the provisions of the Practice Code concerning the construction of concrete, reinforced concrete and pre-stressed concrete works - NE 012-99.
1.4.4 Precast units, erection
For structures of precast beams and slabs, the precast units shall be itemised, and shall have paint inscriptions with the manufacturing date and the type of the unit.
The erection of the precast units must be managed by a specialised engineer and supervised by skilled foreman with training in such works.
The erecting plant must ensure the safety of the erection works.
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Jointing shall be achieved in the shortest time possible after erection.
The erection of precast units shall be checked in accordance with annex III.1 of the Practice Code concerning the construction of concrete, reinforced concrete and pre-stressed concrete works - NE 012/99.
Tolerances for the dimensions of the precast units are shown in STAS 8600/79, STAS 7009/79 and STAS 6657/1-89. See also the Practice Code concerning the construction of concrete, reinforced concrete and pre-stressed concrete works - NE 012/99 Code of practice for construction of concrete, reinforced concrete and pre-stressed concrete precast units NE 013/02.
1.4.5 Works acceptance
1.4.5.1 Testing of works
Tests shall be made in the presence of the Engineer.
1.4.5.2 Remedial works
If the entire superstructure or parts of it do not correspond to the provisions of the Contract, the Contractor shall carry out the necessary remedial works. After the survey and the analysis of the defects, the contractor shall submit a program of the repair for the approval of the Engineer.
For defects affecting the quality of the structure, the safety and durability in service the programme shall contain:
a detailed survey report of the defects;
causes, supplementary tests, investigations and analysis done;
the short and long time consequences shall be estimated;
proposed remedial works.
Depending on the findings and on the conclusions of the study, the engineer may proceed as follows:
approve the repair project, with possible observations
order the demolition of the whole or part of the work and rebuild at the expense of the contractor.
For defects concerning the geometry of the construction, the quality or the colour of the surfaces, but not affecting the safety and the bearing capacity of the work, the remedial works shall be agreed with the Engineer.
Open fissures, which might compromise the stability and durability of the works shall be repaired observing the provisions of the Standard C 149/87, regarding repair of concrete and reinforced concrete elements.
1.5 SCAFFOLDING AND CENTERING
1.5.1 General provisions
The present section concerns the temporary works, which, depending on the destination, may be divided into:
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scaffolding and centering for the support of the structures during construction;
service scaffold for the movement of the workmen, tools and materials;
protection devices, in case of works carried-out under circulation (for instance against materials or tool falling).
1.5.2 Design of temporary works
The Contractor shall design the temporary works to fulfil the following conditions:
to assure the security of workmen and of the permanent works;
to take account of the factors imposed by the permanent works;
deformations of the temporary works must not harm the permanent works during setting or hardening;
include details of construction stages;
contain working drawings and technical reports.
A complete set of the design must be permanently on site at the Engineer’s disposal.
The drawings shall define the geometry of the temporary works, as well as the nature and parameters of all the component units.
The drawings shall also emphasize:
measures for the stability and protection of the foundations;
assembling procedure of the component units of scaffoldings and centering;
supports of the bearing elements, which must be compatible with their own stability and with the stability of the units, which they rest on;
bracing system for assuring stability;
rules to be observed during the handling and for all the operations of adjustment, keying, uncentering, form stripping, dismounting;
counter flexures and the tolerances in construction;
concreting procedure; the free deformation of the concrete due to contraction and prestressing;
devices for measurement of deformations and settlement.
The technical report must contain:
specification of necessary materials;
instructions for the erection of temporary works;
instructions regarding the units whose failure might affect the security of works.
1.5.3 Construction and use of temporary works
The quality of the materials, new or re-used, shall correspond to the provisions of standards in force.
The Contractor must present quality certificates for the new materials; for the re-used materials the Contractor must guarantee the equivalence of their quality with that of new materials.
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The use of re-usable elements or materials is allowed as long as the deformation or the effect of fatigue does not risk compromising the safety of the works.
The Contractor must emphasize in the drawings the admissible number of re-uses.
Rejected materials shall be removed from the site.
1.5.4 Construction, use, trials
Any deformation of the temporary works shall be checked by the Contractor. The control levelling shall be related to benchmarks shall also to be checked by the Contractor. The results of the measurements shall be transmitted to the Engineer.
The Contractor shall take necessary steps to avoid deformation.
The Contractor shall ensure the regular maintenance of the temporary works.
1.6 FORMWORK
1.6.1 General data
Formwork are carried out only on the basis of design, drafted by authorized design offices, observing the provisions of STAS 7721/90 and fulfilling following conditions:
to ensure the shape, dimensions and finishing degree provided by the design, for the construction to be achieved, observing the admitted tolerances under annex III.1 of the Practice Code concerning the construction of concrete, reinforced concrete and pre-stressed concrete works - NE 012/99;
to be tight enough to avoid loss of cement laitance;
to be stable and resistant to the loads expected during construction;
to be easy to mount - dismount, without damaging the lined concrete elements or the components of the formwork or propping;
to permit, at stripping, a gradual loading of the concrete structure;
to permit the closing of the joints, avoiding the formation of wedges or sills;
to permit the easy closing of the openings for the control inside the formwork and for the discharge of waste water, before start of concreting;
the surfaces in contact with the concrete must be clean, without cracks or other defects.
Formwork may be divided into:
fixed formwork, processed and erected on the site and used for a single concrete casting;
stationary dismountable formwork, achieved from elements or sets of elements reusable for a certain number of concrete castings;
mobile dismountable formwork, which are moved and take successive positions in steep with the concrete pouring (sliding or stepping forms).
Function of the nature of materials, the formworks may be also divided into:
wood or wood lined forms;
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plywood forms;
veneered form or similar, joined or treated with resins, or similar types;
metallic forms.
1.6.2 Supplementary conditions for formwork
Beside the general conditions herein before, the formwork must also fulfil the following specific conditions:
to permit the proper placement in position of the reinforcement and of the prestressing cables
to permit safe fixing of embedded items in conformity with the design
to permit a good compaction of the concrete, especially in the anchoring zones of the pre-stressed beams
to afford working and moving possibilities for the crew carrying-out the concreting, avoiding their circulation on the pre-stressed reinforcement
to afford the elastic shortening due to pre-tensioning and the gradual loading of the own weight, according to the provisions of the design
if necessary, to be provided with handling lugs and with devices for fixing of form vibrators.
1.6.3 Preliminary works and acceptance
Before each re-use, the formwork shall be checked, adjusted, repaired and re-secured.
The number of re-uses shall be established with the agreement of the Engineer.
In preparation for re-using, the formwork shall be treated as follows:
they shall be carefully cleansed, repaired and washed before and after the re-use. It is not allowed to cleanse the forms only by air jet
the surfaces in contact with the concrete shall be oiled by a solution allowing easy stripping; if the solution is oily, lubricant, contact with reinforcement shall be avoided.
For the correct erection of formwork each stage of the operation shall be checked, namely:
before erection, the preliminary works and the units or sets of units of the formworks and propping
during erection, the correct position and the manner of fixing
finally, the acceptance of the formworks, inscribing the findings in the "Register of reports concerning the quality control of concealed works".
1.6.4 Formwork erection, treatment during concrete hardening
1.6.4.1 Erection of formwork
Formwork erection includes following works:
marking of the position
provisional assembling and supporting of the panels
control and position correcting of the panels
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joining, binding and definitive propping and bracing.
1.6.4.2 Supporting elements of the formwork
If the supporting elements of the formwork rest on the ground, the loading shall take account the compaction of the ground and the possibility of softening, in order to avoid settlement.
If the ground is frozen or exposed to frost the means of support shall avoid displacements due to temperature change.
1.7 REINFORCEMENT
1.7.1 Steel for reinforcement
The usually types and the range of applicability are shown in the following table, corresponding to the provisions of the Practice Code concerning the construction of concrete, reinforced concrete and pre-stressed concrete works - NE 012/99.
TYPE OF THE STEEL SYMBOL FIELD OF APPLICABILITY
Round smooth bars STAS 438/1-89 OB 37 Strength reinforcement
Drawn smooth wire of reinforced concrete STAS 438/2-91
STNB Strength reinforcement of welded wire fabric or welded carcasses;
repartition reinforcementWelded wire fabric for reinforced concrete SR 438/3/1998
STNB
Deformed bars for reinforced concrete. STAS 438/1-89
PC 52Strength reinforcement for concrete
of min C 12/15 (Bc 15) class
PC 60Strength reinforcement for concrete
of min C 16/20 (Bc 20) class
Prestressing reinforcement-smooth wire STAS 6482/2-80-printed wire STAS 6482/3-80-strands
SBPI andSBP II
SBPAI andSBPAII
Strength reinforcement for concrete of min C 25/30 (Bc 30) class
For imported steel, the quality certificate from the import company is mandatory. Imported steel must be technically illustrated mentioning the field of applicability.
In this certificate, the corresponding type of steel from STAS 438/1-89, STAS 438/2-91, STAS 438/3-98 or STAS 6482/1-73 shall be shown. The equivalence must take in account all the quality parameters.
If doubts do exist, concerning the equivalence, the contractor shall use the steel only after laboratory tests, with the written approval of the Engineer.
1.7.2 Delivery and marking
The delivery of the steel bars is made according to the valid composition, and is accompanied by the quality certificate (quality inspection certificate; conformity declaration) and after steel bars is certified by an authorised company, by a copy of the conformity certificate.
The documents that accompany the steel bars delivery should contain:
name and type of steel bars, used STAS;
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information for the identification of the batches;
net weight;
determined values concerning the performance criteria.
Each flake or bunch of bars or melded wire should bear a label containing.
the mark;
the reinforcement type;
the number of the batch and of the flake or bunch;
the net weight;
the quality control.
The steel delivered by intermediary suppliers shall be accompanied by a quality certificate containing all the data in the quality documents issued by the steel bars producer.
1.7.3 Quality control
Quality control of the steel shall be according to the provisions of section 17 in the Practice Code NE 012-99 Code of practice for construction of concrete, reinforced concrete and pre-stressed concrete precast units NE 013/02.
1.7.4 Bending, erection and fixing of reinforcement
Recommendations regarding bending, erection and binding of reinforcing bars, are given is Annex III.1 of the Practice Code NE 012/99 Code of practice for construction of concrete, reinforced concrete and pre-stressed concrete precast units NE 013/02.
The following conditions shall be observed for any type of pre-stressed reinforcement:
the quality certificate of the steel batch shall be checked; in its absence or if the conditions of transport and storage are in doubt, the quality shall be checked according to STAS 1799/88 by means of mechanical tests (tensile strength, alternating bending, etc.);
steel bars or wires shall be cleaned, surface rust shall be removed by wire brush to secure a proper bond;
steel showing signs of corrosion may be used only after trials proving that the physical/mechanical parameters are not affected;
reinforcement to be simultaneously pre-stressed shall be from the same batch;
damaged bars shall not be used, straightening is forbidden. However, slight deformation due to transport or storage may be mechanically straightened at temperatures over +10ºC;
for individual pre-stressed reinforcement, tests shall be carried out by a licensed laboratory on short samples, according to STAS 6605/78 "Tensile strength test of steel bars, wire and wire products for pre-stressed concrete”;
for pre-stressed reinforcement the actual value of the elastic modulus shall be established on site at the same time as the determination of the loss of tension due to friction.
For the design preparation erection and placement of the pre-stressed reinforcement and also for the tensioning blocking and injection, the provisions of sections 7,9 of STAS 10111/2-87 and of sections 3,4,8,9 of the Practice Code NE 012/99 and section 10 of Practice Code NE 013/02 are compulsory.
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1.7.5 Tolerances in erection
Tolerances in bending and erection of reinforcement are given in the Annex II.2 of the Practice Code NE 012/99.
1.7.6 Welded wire reinforcement.
Drawn smooth wire STNB or profiled wire STPB shall be according to STAS 10107/0-90.
Loading, unloading and transport of welded wire shall be done carefully, avoiding damage, deformation or weld breaking.
Trials or determinations specific for welded wires, including checking of the knot (hitch; bend) welding quality shall be according to STAS 438/3-98.
After removal of rust the decrease in section of the bars shall not exceed the tolerances provided in the standards.
The minimum distance between reinforcement and the minimum diameters allowed for reinforced or precast concrete shall be according to STAS 10111/2-87.
1.7.7 Reinforcement repairs
Reinforcement repairs shall be according to the provisions to the design and of STAS 10111/2-87.
Welding of mechanically improved reinforcement (e.g. drawn wire) is forbidden.
1.7.8 Spacers
In order to ensure the correct cover plastic spacers shall be used. The use of metallic or wooden spacers is forbidden.
1.7.9 Substitution of designed reinforcement
Where the designed reinforcement is not available substitution with alternatives shall be only with the Engineers’ approval.
The substitution shall be recorded in the construction plans that accompany the Construction Certificate.
1.8 CONCRETE
1.8.1 General specification
The present section the general specifications necessary for the design and construction of concrete, reinforced concrete and pre-stressed concrete for bridge structures.
Specifications for concrete are given in annex I.1, I.2, I.3, I.4, I.5 and I.6 of Practice Code for the construction of concrete, reinforced concrete and pre-stressed concrete works" NE 012/99, approved by MLPAT by Order 59/N of august 24 1999 and the provisions of STAS 10112/2-87 and STAS 1799/88.
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The concrete class shall be established on the basis of the characteristic strength f.ck.cil. (f.ck.cub) - the compressive strength in N/mm2, either on cylinders of 150/H300 mm or on 150 mm cubes at 28 days. Samples shall be kept according to STAS 1275/88.
Concrete classes in Practice Code NE 012/99 are given below.
Concrete class
according to NE 012-99Concrete
class
Concretemark
Recommendation
s concerni
ng minimu
m classes of
concrete
SubstructureSTAS 10111/1-77
SuperstructureSTAS 10111/2-87
*C2,8/3,5 Bc 3.5 B 50 Levelling and filling concrete
C 4/5 Bc 5 B 75 Concrete screed laid to fall
*C6/7,5 Bc 7.5 B 100
Mass foundations of plain concrete, for embankments, retaining walls, wing walls
on soil without underground water
C 8/10 Bc 10 B 150
- Ditto, in soils with under- ground water- Mass foundations of reinforced concrete for culverts, wing walls retaining walls,
bridge piers and abutments-Mass elevations of plain concrete for
culverts, wing and retaining walls, bridge piers and abutments, retaining and back
walls included
Mass units of plain and reinforced
concrete
C 12/15 Bc 15 B 200
Reinforced concrete elevations, face concrete, reinforced concrete, bearings and
panels
Superstructure for cast in-site pipe
culverts
C 16/20 Bc 20 B 250Superstructure and
pipe culverts of precast units
*C18/22,5C 25/30*C28/35C 30/37*C 32/40C 35/45C 40/50C 45/55C 50/60
*(Bc22.5)Bc 30Bc 35
-Bc 40
-Bc 50
-Bc 60
B 300B 400B 450
-B 500
-B 600
-B 700
Superstructure of pre-stressed
concrete
Concrete classes (*) are not in the European Norms and remain valid only until the revised codes (according to Euro code 2) come into force.
1.8.2 Concrete requirements
a) Strength
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The relation between the water/cement ratio and the compressive strength of concrete shall be determined for each type of cement, aggregate and age of concrete. The admixtures in concrete may interfere in the determination of the water/cement ratio.
The characteristic strengths on cylinders or on cube samples are:
Concrete of resistance class
*C 2,8/3,5 C 4/5 *C 6/7,5 C 8/10 C 12/15
f.ck.cil. N/mm2 2,8 4 6 8 12f.ck.cub. N/mm2 3,5 5 7,5 10 15
Concrete of resistance class
C 16/20 *C 18/22,5 C 20/25 C 25/30 *C 28/35
f.ck.cil. N/mm2 16 18 20 25 28f.ck.cub. N/mm2 20 22,5 25 30 35
Concrete of resistance class
*C 32/40 C 35/45 C 40/50 C 45/55 C 50/60
f.ck.cil. N/mm2 32 35 40 45 50f.ck.cub. N/mm2 40 45 50 55 60
*) Concrete classes that are in force until revised codes are issued.
b) Durability
The levels of performance for concrete impermeability are:
The max depth of water penetrationWater pressure (bars)100 200
Impermeability degree
4
8
12
The impermeability degree is according to STAS 3622/86.
The freezing - thawing strength of the concrete characterized by the freezing degree (number of freezing thawing cycles), shall be according to the provisions of Table 5.4 of the Practice Code NE 012/99.
The levels of performance at freezing of the concrete are.
Concrete freezing degree Number of freezing-thawing cyclesG 50 50G 100 100G 150 150
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1.9 PRE-STRESSED CONCRETE BRIDGE SUPERSTRUCTURES
1.9.1 General specifications
This section concerns the works or parts of works of pre-stressed concrete, pre or post tensioned, in structures with steel or precast concrete beams. The cantilever method of construction is not subjected to these specifications.
Precast units used in structures shall be accompanied by quality certificates.
The construction of the works shall observe the design, Practice Code NE 012/99 Part B for the construction of pre-stressed concrete works and Practice Code NE 012-99 Part A for the construction of concrete and reinforced concrete works.
1.9.2 Formwork, moulds, supports for formwork
The Contractor shall provide drawings to the Engineer for all temporary works including positions of expansion joints.
1.9.3 Reinforcement
1.9.3.1 General parameters
Reinforcement of pre-stressed concrete units shall be in accordance with STAS 438/1-89 "Hot rolled steel bars for concrete. Marks and general conditions of quality" and STAS 438/2-91.
The replacement of bars by equivalent bars of another diameter shall only be with the agreement of the Engineer.
Imported pre-stressed reinforcement may be used based on technical agreement, according to the guide regarding the agreement method of reinforcement for prestressing used in civil, industrial and special constructions - GAT 253 (MLPAT).
Reinforcement of prestressing cables shall be steel wires for pre-stressed concrete, quality I, according to STAS 6482/1-73 and 6482/2-80.
Wire shall be delivered in single cores of minimum 2 mm diameter. Every wire strand shall have a metallic label containing:
the number of the strands and the number of the batch,
the quality and the producer’s quality punch mark
and shall be accompanied by a quality certificate.
The reception of the steel shall be according to the rules and quality control procedures provided by STAS 1799/88 "Constructions of concrete, reinforced concrete and pre-stressed concrete. Specifications for the quality control of materials and concrete".
The Contractor shall check the mechanical parameters as follows:
tensile strength and the number of alternate bending for each strand and
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for 10% of the strands - the flow limit, the relative elongation at failure and the number of twin strands at failure.
These parameters shall be measured on samples taken from both ends of the cable.
The geometric, chemical, mechanical and technologic features of pre-stressed reinforcement shall comply with the provisions of:
STAS 6482/2-80 "Steel wire and wire products for pre-stressed concrete. Smooth wire"
STAS 6482/3-80 "Steel wire and wire products for pre-stressed concrete. Printed wire"
STAS 6482/4-80 "Steel wire and wire products for pre-stressed concrete. Strands"
Wires with pronounced corrosion or with notches shall not be used as pre-stressed reinforcement.
Wire strands slightly corroded shall be cleaned by wire brush.
1.9.3.2 Handling, transport and storage
Preparing pre-stressed reinforcement
For any type of pre-stressed reinforcement the following preliminary measures shall be taken:
a) the quality certificate of the batch of reinforcement shall be checked. If there are doubts regarding the haulage and storage conditions - rust, dirt, deformation, etc - the quality shall be tested by the producer or an authorized laboratory to confirm that the physical/chemical features of the reinforcement were not affected.;
b) the surface of the steel shall be cleaned; the loose rust shall be brushed away, to secure a proper bond for concreting or injection grouting;
c) reinforcements that are to be pre-stressed simultaneously shall come from the same batch;
d) reinforcement bent locally shall not be used; straightening is forbidden;
Steel bars deformed during haulage or storage shall be mechanically reformed at a temperature above +10ºC.
e) rewinding of wires and strands at rolling diameters lower than those delivered shall be avoided.
For individual pre-stressed reinforcement the elastic modulus shall be determined by a laboratory as per the provisions of STAS 6605/78.
In the case of the post - tensioned reinforcement specified in Annex 4 of the Practice Code NE 012/99 Part B, the elastic modulus may be estimated at 1.92 x 105 N/mm ±2%. For other types of reinforcement, the elastic modulus shall be given by the producer or be determined by authorized laboratories.
Manufacturing and positioning of the pre-tensioned reinforcement
The positioning of pre-tensioned strand and other reinforcement fixings shall be strictly in accordance with the design of the pre-tensioned concrete element.
Cut ends must not produce deformation that may hinder the introduction of the reinforcement through the spacing screen in the end blocks of the pre-tensioning or other constraint positions. Special attention shall be paid to prevent reinforcement being in contact with any parts of the face of walls or platforms.
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The positioning deviations in the section of the pre-tensioned reinforcement element shall not be more than 3 mm from the design position unless otherwise specified. Negative tolerances are not permitted in the thickness of the covering concrete.
To position and maintain pre-tensioned reinforcement in the design position, a metal spacing screen shall be used. Some of these screens are fixed and other are mobile. The diameter of the screen holes shall be larger than the pre-tensioned reinforcement diameter by 1 - 2 mm in case of wires and 2 - 3 mm for strand.
Blocking devices at the strand ends, of the metal mould shall be placed so that the maximum deviation of the reinforcement from the last spacer does not exceed a slope of 1/10.
To allow fixing in position of non-pre-tensioned reinforcement, it is permitted to pre tension in two steps. The pre-tensioning force in the first step shall be established according to the manufacturing technology adopted but it shall not be over 40% of the prescribed control force.
Non-pre-tensioned reinforcement shall be mounted, positioned and tied with black smooth wire and then the final pre-tensioning shall be done.
Systems positioning the pre-tensioned or non-pre-tensioned reinforcement with metal spacers are not permitted.
If joining devices for reinforcement are used, they shall be positioned to allow the free elongation of the reinforcement and not involve the other fittings during pre-tensioning. The devices shall have the load capacity at least of 92% of the breaking force of the joined reinforcement.
1.9.4 Demands and performance criteria for concrete
The concrete used for the pre-tensioned concrete elements/structures shall fulfill the following.
Minimum class C 20/25 for pre-tensioned reinforcement of bars having;
Rpo2 590 N/mm2 and Rm 890 N/mm2;
C 25/30 for elements with wire - drawn pre-tensioned reinforcement (wire, strands);
During concreting the following provisions are required:
a) Where internal vibrators are used for concrete compaction the following measures shall be taken to avoid contact between the internal vibrator and the pre-tensioned reinforcement or cases for channel forming.
the points for introducing the internal vibrators shall be visibly marked.
in the points where the internal vibrator is introduced special constructive devices (metallic cases, braces and bars) are provided to prevent contact between the internal vibrator and the post-tensioned reinforcement cases.
b) A special attention shall be paid to the concrete compaction in the anchor zones.
c) At elements with pre-tensioned strand reinforcement, the concreting shall be continuous so that between starting the pouring of the first element and finishing compacting the last element, the time shall not exceed 45 min. at a working temperature of 30º.
d) Stripping of formwork from the pre-tensioned concrete construction shall only be done after their pre-tensioning (partial or total, according to the design provision).
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1.9.5 Construction of the works
1.9.5.1 Concrete binding of precast units
Concrete binding between the precast sections shall be with concrete class C 32/40 (Bc 40), the same as the concrete class of the precast units.
The Contractor shall propose for the Engineer's agreement details concerning the security of the cable channels.
Concrete binding between plates shall be made by concreting the voids for connectors with concrete C 25/30 (Bc 30), carefully vibrated to achieve the integration between beams and slabs.
1.9.5.2 Stressing and anchorage blocking
The Contractor shall propose for the Engineer's agreement:
details of materials;
the pre-stressing works program;
the name of the chief of the pre-stressing works site;
origin and professional quality of the staff charged with the construction of the pre-stressing works.
The pre-stressing works program shall be included in the general schedule of the works.
The pre-stressing program must emphasize:
the means and the instructions necessary for the use of the materials in the successive operations;
the processing procedure of the pre-stressing reinforcement;
measures for the protection of the pre-stressing reinforcement
details of every stage of pre-stressing
Before stressing the temporary protection of reinforcement cables and blockings shall be checked and the concrete strength verified.
During stressing:
the order of the cable stressing;
table with the relations between the tensile force and the elongations of the cables and with the calculated and actual rate of friction;
measurement method of strains and elongations;
the steps to be taken in case of accident, abnormal elongations or failure of wires.
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After pre-stressing:
revision of the temporary protection, especially at the seat of the anchorages;
definitive protection and injection program;
checking procedure of the channels left free.
The results of the pre-stressing shall be registered in a form of pre-stressing the type shown in Annex 12 of the Practice Code NE 012/99 Part B.
1.9.5.3 Grouting of the cables
Injection shall be performed according to a program drafted by the Contractor and including:
the parameters of the injection grout and the hardening duration;
the conditions for the use of the injection material and the destination of material needing disposal in case of accident;
the detailed order of the operations - air blowing or washing the channels;
the detailed order of injection operations and corresponding tests;
the volumes of injection material for every cable and groups of cables;
the rules to be observed in case of accident or unfavourable weather.
All grouting will observe the provisions of the Practice Code NE 012/99, part B, 8th section, by observing the dates in the 13 and 14 Annex regarding the mixture of grouting and grounding form.
1.9.6 Quality control, works acceptance
The reception of the precast units of pre-stressed concrete or of the precast units to be assembled by pre-stressing shall be made by the producer as per STAS 6657/1-89 and according to the design or to the internal standard for the manufacture of the precast unit.
The Contractor shall certify the quality of the batch of delivered precast units. The document shall include data resulting from the quality tests.
The repair of the pre-stressed concrete units with slight defects, not affecting the bearing capacity or the durability shall be according to a program drawn up by the contractor and agreed by the engineer.
Units with severe defects - segregations, voids, and cracks are not acceptable and shall be removed from the site.
1.10 ACCESSORIES
1.10.1 Bearings
The materials of the metallic bearings must satisfy the minimum conditions of quality provided by STAS 4031/77 and STAS 4031/2-75.
For elastomeric bearings, the quality of the material shall be in accordance with STAS 10167/83.
The Contractor may propose other types of bearings for the approval of the Engineer.
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1.10.2 Water outlet devices
Water outlet devices are, generally, prefabricated of standard type and are mounted in a manner to make possible the outlet of the water, without infiltration in the body of the flooring.
The Contractor may propose another type of device, for the approval of the Engineer.
1.10.3 Railings
Steel railings shall be painted; the quality and the colour of the paint shall be agreed by the Engineer.
1.10.4 Kerbs for footpaths
Kerbs for footpaths may be of precast concrete or of stone. The quality of the concrete or stone, the surface treatment and the dimensions are detailed on the drawings. Kerbs shall be laid observing the gradient and the cross fall of the road.
Precast concrete kerbs shall be concrete of minimal class C 32/40, using cement I 42,5, with minimal degree of impermeability P 8 and should withstand at least 150 cycles of freeze - thaw.
1.10.5 Ant seismic devices
For bridges of long spans, located in seismic area 7 or greater, anti seismic devices are required.
These devices are detailed in the Particular Specification.
1.11 WATERPROOFING AND EXPANSION JOINTS
1.11.1 Waterproofing
1.11.1.1 General provisions
Generally, bridge waterproofing consists of:
the waterproof layer on the whole surface of the bridge.
the waterproofing layers must be connected to the outlet nozzles and to the expansion joints.
Waterproofing consists of the following layers:
levelling layer;
priming layer;
adhesion layer;
principal layer;
protection layer.
The functionalities of some layers can be merged in various solutions of the specialized forms of waterproofing.
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The waterproofing mainly consists of:
liquid foil, fast hardening;
waterproofing membrane;
The laying technology may be:
by spraying;
by hot sticking of the membranes with bitumen solution;
by cold sticking with synthetic resin;
self-adhesive membranes;
sticking by membrane overheating;
mason’s brush or brush laying.
The term “waterproofing layer” as used herein after refers to all the component coats, namely: the levelling layer, priming, principal base waterproofing layer and protection cover.
1.11.1.2 Technical specification
The waterproofing layer shall be guaranteed for 8 years for normal bridges over passes or viaducts.
The materials used in the waterproofing layer shall be chemically inert.
The waterproofing layer shall be also capable of being repaired (half of the carriageway at a time).
The waterproofing layer shall support the low speed transport for asphalt laying.
The waterproofing layer shall be allow for adhesion of asphalt.
The following characteristics shall apply:
ultimate strength: 800 N/5 cm;
elongation at break: min 20 %;
static boring perforating resistance European Norm L4 250 N on the 10 mm diameter ball;
stretch adhesion N/mm2: Min. 0,5;
flexibility on 50 mm diameter bolt: without cracks at - 100 C;
water absorption in 24 hours: 0,5 %;
max. temperature for physical stability of a membrane: 1200 C;
temperature of the poured asphalt coat without modifying the physical-mechanical features: 1800 C;
temperature field in current usage: - 200 C ÷ + 700 C;
temperature field of the environment where the waterproofing layer is laid: + 50 C ÷ + 300 C.
The top layer of the waterproofing should be chemically compatible with the components of the asphalt in order to avoid the waterproofing attacking.
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1.11.1.3 Prescriptions for construction
Levelling layer
The levelling layer of the waterproofing shall be of M 100 cement mortar with a smooth surface finish and no irregularities bigger than 2 mm.
Cement mortar M 100 work shall be achieved with cement II B - S 32,5 according to SR 1500 and the aggregates shall have a maximum dimension of 4 mm.
Checking of levels and irregularities shall be made using a 3 m board in any direction. Only one measurement of ± 5 mm is allowed.
The levelling layer surface shall be prepared as follows:
all sharp edges, prominences, aggregates incompletely embedded in concrete, grease spots and any other foreign matters should be removed;
the levelling layer applied;
the levelling layer shall be cleaned by water jet and air blasted so that the following layers may be applied on a clean and dried surface.
Priming layer
The solution used for the primer may be of bitumen or synthetic resin. The components of the solution shall not contain elements which may be attacked chemically by the concrete.
The primer shall be applied by brushing or mechanical spraying
The primer shall be applied on the dried surface of the levelling layer at a temperature over +50 C.
The whole surface shall be primed.
The passage of pedestrians or any kind of equipment is forbidden
Waterproofing layer
The waterproofing layer shall be applied to the priming layer using the specific method for the membrane to be used.
The membrane shall be continually applied assuring its adherence to the whole surface where it is laid. Swelling or unbound edges are not allowed. Continuous and uniform adherence of membranes applied in strips shall be provided.
Connections to the water outlets shall be watertight and ensure water discharge.
At expansion joints, the waterproofing shall be treated according to the design and the type of the device used to cover the joint.
The waterproofing layer edges shall be sealed by elastic putty seams.
For membranes laid by heating, the temperature of the heating source shall not be higher than 250 0 C or higher than the temperature at which the membrane changes its physical-mechanical and chemical characteristics.
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Waterproofing membranes shall be laid at a temperature of at least + 50 C.
Protection layer
The protection layer may be:
concrete layer 5 cm thickness, achieved of concrete class C 20/25 (Bc 25), reinforced with zinc-plated wire 1,18 - 2,5 mm diameter with square meshes 3-8 cm or type Buzau welded wire net of 4-5 mm diameter with meshes 10 x 10 cm.
Concrete for the protection layer shall be using cement II A - S 32,5 and aggregates with maximum dimension of 7 mm.
bituminous mastic 1 - 2 cm thickness;
protection membranes stuck to the waterproofing membranes.
Waterproofing membranes without protection waterproofing layer may also be used.
The verifying and reception of the waterproofing works will be done in stages, as follows:
during construction of various layers of the waterproofing;
at completion of waterproofing works.
Checking at the end of the waterproofing works is usually visual, but, where required by the Engineer, a test by water flooding to a height of maximum 5 cm shall be made over a 24 hour period.
Defects found during construction may be repaired according to the Contractors’ proposals subject to the approval of the Engineer.
Defective work shall be replaced.
The following standards shall apply:
SREN ISO 527/2-00 “Plastic materials. Determination of the traction (tension) features”. Strength and elongation at break;
SR 137/95 “Bitumen waterproofing materials. Regulations and methods of control”;
STAS 5690/80 “Plastic materials. Determination of water absorption”;
Order MT 497/98 "The normative for the characteristics of the non paraffin bitumen for roads";
SR-ISO 2409/94 “Varnishes and dyes. Determination of the film adherence on the support";
STAS 6615/1 - 74 “Adhesives based on elastomers. Viscosity determination";
STAS 9199/73 "Bituminous mastics for insulations in constructions. Methods of analysis and test."
1.11.2 Covering expansion joints
1.11.2.1 General
Devices for the expansion joints covering used on road bridges shall assure:
the free movement of the decks ends in the joints;
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the continuity of the carriageway on the expansion joints zone;
prevention of leaking and water infiltration.
Generally the components of devices used for covering the expansion joints are:
elastomeric elements that assure movement;
metallic support elements;
special concrete for fixing metallic parts;
special mortar;
means of collecting and removing infiltration water.
Where work is carried out on bridges in use, the device shall permit working on half of the carriageway at a time, without modifying the characteristics of the expansion joint.
The term” device” means all the components.
1.11.2.2 Technical features
The guarantee period of the device shall at least 10 years of normal use of the bridge. The elastomeric element should be interchangeable. The guarantee period of the elastomeric element shall be at least 5 years.
The company supplying the device should assure:
delivery of the interchangeable elements for 30 years from the date commissioning;
delivery of tools and equipment for installing the device and changing the elastomeric element;
commissioning the device;
special instructions for construction and maintenance.
The device should comply with the following physical- mechanical characteristics in a temperature range of - 35 C to + 80 C:
free movement of the structure to the prescribed value;
metallic elements should resist corrosive agents;
to be watertight;
shall be fixed to the structure of the bridge taking vertical and horizontal forces.
For 1 m of bridge these forces are:
vertical force 11.2 tf;
horizontal force 7.8 tf.
The elastomeric element should have the following characteristics:
shore A hardness 60 ± 5
breaking limit at stretch 12 N/mm2
breaking limit at compressive load 75 N/mm2
settling under max. vertical load max. 15%
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min. elongations at break 350 %
oil resistance:
Variation of the physical and mechanical characteristics:
shore A hardness , max ± 5
loss of breaking limit, max.% - 15
elongation at break, max. % - 15
Nom-friability at low temperatures
min. temperature - 35o C
Accelerated ageing resistance:
loss of breaking limit, max.% - 15
elongation at break decrease, max. % - 30
increasing of Shore A hardness max. % 10
Ozone resistance - after 100 hours no cracks shall be visible
1.11.2.3 Prescriptions
Special concrete
Concrete in beams shall be at least class C28./35 (Bc 35), settling by T 3/4 - 100 ± 20 mm.
Aggregates used for concrete shall be crushed rock. The concrete shall be class I 42.5 R according to SR 388 - 1995.
The concrete shall have a degree of frost resistance G 150.
The trafficking of class Bc 35 concrete shall not be allowed for 28 days after concreting.
Special concrete with fast hardening additives may be permitted to receive traffic after 10 days.
Where fastening is done with rag bolts, the concrete in which these bolts are anchored, shall be at least class C 20/25 (Bc 25).
Cement used for concrete shall be I 32,5 according to SR 388 - 1995.
Special mortar
For surface levelling under some types of devices or for lateral fixing of the elastomeric element, special mortar containing synthetic resin shall be used subject to the Engineer’s approval.
Elastomeric elements
The elastomeric elements may be:
reinforced neoprene panels;
special sections, shut or open, made of neoprene;
neoprene flat bars.
Fixing metallic accessories
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Metallic accessories have special sections adapted to the elastomeric elements. They shall be embedded in the structure and the interchangeable elastomeric elements fixed to them.
The neoprene rubber-tightening strip shall be continuous both on the whole length and width of the covering device. Only one vulcanized patch may be done on the whole length. On the vulcanized zone, a thickness tolerance of ± 10 % of the nominal thickness of the strip is allowed.
Testing of the physical-mechanical and chemical characteristics shall be in conformity with the following standards
SR ISO 7619/01 “Vulcanized elastomers. Determination of shore a hardness”;
SR-ISO 37/97 “Vulcanized and thermoplastic rubber.
Determination of stress-strain characteristics at traction”.
SR ISO 1817/00 “Vulcanized elastomers. Methods of test for resistance to liquids”;
SR ISO 188/01 “Cured elastomers. Accelerated ageing testing”;
SR ISO 812/01 “Vulcanized rubber. Determination of brittleness temperature”;
STAS R 9449/74 “Vulcanized elastomers. Determination of ozone cracking resistance under static conditions”;
ISO 815+A1/95 “Vulcanized elastomers. Determination of permanent deformation at compression and constant deformation at environment and high temperatures”;
SREN 10002/1-95 "Metallic materials. Testing to traction. Testing method (to the environment temperature)";
SR 13170/93 "Metallic materials. Impact bending test. Special test specimens and estimation methods";
SREN 10045/1-93 "Metallic materials. Impact bending test on the Charpy test specimen. Part I: Testing method".
1.12 BRIDGE DECK PAVEMENT
1.12.1 General provisions
This section contains the general technical conditions to be fulfilled in the construction of bituminous road coverings type cast asphalt - for bridge carriageways and footpaths.
The pavement shall be hot laid from mixtures of natural aggregates, filler and non-paraffin bitumen for roads, and observe the conditions of following standards:
STAS 11348/87 "Road works. Bituminous pavement for the way on the bridge. Technical conditions of quality"
STAS 175/87 "Road works. Poured bituminous coverings, hot laid. General technical conditions of quality";
Ind.AND 546/99 "Normative regarding hot construction of the bituminous coverings for the carriageway of the bridge".
The bituminous covering shall be chosen taking in account the technical class of the road or the category of the street, as per STAS 11348/87 table 1 according to the Norm. AND 546/99.
The types of mixtures are given in the table.
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Item The type of asphalt mixture SymbolThe max.
dimension of the granule
The field of application
1.Rolled asphalt concrete, with pure bitumen
BAP 16carriageway covering of the
roadway bridges
2.Rolled asphalt concrete, with modified by polymers bitumen*)
BAmP 16carriageway covering of the
roadway bridges
3. Poured hard asphalt ADT 8covering to the bridges with
concrete plate4. Poured asphalt AT 7 covering on side walks
5. Poured asphalt mortar MAT 5waterproofing protection or
equalizer layer of the bridges carriageway
Note: *) for bridges situated on public roads, with heavy intense traffic, for the purpose of increasing the strength at permanent load, at high temperature and the strength at cracking at low temperature.
Bituminous covering on the bridge carriageway shall be laid on a protection layer executed according to STAS 11348/ 87.
Bituminous covering of the footways shall be according to STAS 11348/87, STAS 175/85, type AT.
Rolled asphalt concrete type BAP shall to be laid only from May - October, at times when the minimum air temperature is +10C. Rolled asphalt concrete using modified polymer bitumen may be used from May – September when the minimum air temperature is +15C. Bituminous surfacing from poured hard asphalt may be used throughout the year provided the condition of the supporting layer is dry, with the temperature of the supporting layer a minimum +5C.
1.12.2 Technical conditions
1.12.2.1 Geometrical data
The thickness of the courses achieved (poured hard asphalt, poured asphalt and poured asphalt mortar, shall have the minimum thickness provided by the table 2 of STAS 11348-87, namely:
poured hard asphalt
- poured mechanically: min 5.0 cm thick
- manual pouring in 2 coats: min 2 x 2.5 cm thick
poured asphalt min 2 cm thick
poured asphalt mortar min 1-2 cm thick.
The total thickness of the covering of rolled asphalt concrete shall be 6 cm and be executed in 2 layers, the thickness of each coat being of 3 cm.
1.12.2.2 Tolerances
The permissible deviation for the thickness of the courses is 10 %.
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The tolerances of cross falls are ± 2.5 mm/m for mechanically poured covering and ± 5 mm/m for manual laying.
The maximum unevenness along the bridge, measured by a 3 m long straight board, are 3 mm for mechanical construction and 5 mm for manual laying.
1.12.3 Materials
The materials for the construction of asphalt mixtures are shown in the table 3 of STAS 11348-87 and shall fulfil the quality conditions provided for in the standards, namely:
STAS 662/89 for natural sand and SR 667/01 for crushing sand 0-3 and chipping (for type 3-8 and 8-16);
STAS 539-79 for filler;
The Normative Ord. MT 497/1998 for bitumen shall be used the bitumen types D 60/80 for hot climatic zones and D 80/100 for cold climatic zones.
Other materials:
quick breaking cationic bituminous emulsion to STAS 8877/72 for the priming coat on reinforced concrete flooring;
thick putty for sealing joints of the waterproofing or of the bituminous pavements at the contact with expansion joints, outlet openings, kerbs.
The mix formula and the physical-mechanical parameters of the asphalt and of the hard asphalt shall observe the provisions of STAS 175/87 (according to the tables).
The mix formula and the physical-mechanical characteristics of the asphalt concrete type BAP or BAmP shall observe the provisions of the Normative. AND 546/ 99.
The composition and the physical - mechanical characteristics of the poured asphalt mortar shall observe the provisions of the STAS 11348/87.
Physical-mechanical characteristicsAsphalt mixtures
Poured hard asphalt Poured asphalt
A. Testing cubes
- Apparent density, kg/cu.m 2400 2400
- Water absorption, % vol. 0 - 1 0 - 1
- Swelling after keeping 28 days in water, max.vol
1 1
- Compression strength at 22ºC, N/mm2, min. 3.5 3.0
- Compression strength at 50ºC, N/mm2, min. 1.7 1.5
- Reducing of the compression resistance after keeping 28 days in water at temperature of 22ºC, % max.
10 10
- Penetration at 40ºC, under a force of 525 N, applied for 30 min. by means of a with the section of 500 mm2, mm
1 - 7 1 - 7
B. Testing on Marshall cylinders
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Physical-mechanical characteristicsAsphalt mixtures
Poured hard asphalt Poured asphalt
- Stability (S) to 60ºC, N. min 5500 1000
- Flowing index, flow (l), min. 1.5 - 4.5 1.5 - 4.5
- Ratio S/I, N.mm, min 1500 1000
The conditions for mix formula and the parameters of the rolled asphalt concretes with pure bitumen are those from the following tables:
Item Specifications Allowing conditions1. The mix formula of the natural aggregates and filler
passing through the sieve of 16 mm, %passing through the sieve 8 mm, %passing through the sieve 3.15 mm, %passing through the sieve 0.63 mm, %passing through the sieve 0.20 mm, %passing through the sieve 0.09 mm, %
90 - 10060 - 8045 - 6025 - 4014 - 2510 - 12
2. The bitumen content, % of the mixture mass 6 - 7
Item CharacteristicsRolled asphalt concrete
Type of bitumenD 60/80 D 80/100
A. Characteristics on Marshall cylinders1. Apparent density kg/cu.m, min. 2350 23502. Water absorption, % vol. max. 1,0 1,03. Stability (S) la 60C, min. 7,5 7,04. Flowing index flow (I) la 60C, min. 1,5 - 4,5 1,5 - 4,5B. Characteristics on untouched tests - carrots1. Apparent density kg/mc, min. 2250 22502. Water absorption, % vol., max 2,0 2,03. Degree of compaction, % min. 70 97
The permissible deviations regarding the mix formula, in percentage of the poured or rolled mixtures weight, shall observe STAS 175/87 and SR 174/2-97.
1.12.4 Priming
The support layer shall be finished as follows:
concrete shall be levelled by a cement mortar rendering. After drying, the surface shall be primed by cationic bituminous emulsion;
support layer of poured asphalt mortar shall be cleaned and primed with cationic bituminous emulsion if the pavement is poured later than 24 hours from the pouring of the mortar.
The mixing, transport and laying of the asphalt mixtures type ATD shall be in conformity with STAS 175/87 and of type BAP, according to SR 174/1-02, SR 174/2-97 and Normative. inf. AND 546/99. The mixtures shall be poured after the priming of the waterproofing course with bituminous emulsion.
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1.12.5 Works control and acceptance
The control of the asphalt mixtures shall be as per STAS 11348/87, chapt.4 and observing the provisions of the Normative inf. AND 546/99.
Quality control of the road covering shall be by non-destructive tests or on core samples and plates, according to SR 174/2-97. Control of geometrical data during construction shall be as per SR 174/1-02, SR 174/2-97.
Acceptance at the completion of the works and final acceptance shall observe the provisions of SR 174/2-97.
1.13 REVETMENT AND STONE MASONRY
1.13.1 General provisions
The physical-mechanical parameters of stone used for masonry and facing works are given in STAS 5090-83.
The choice of the natural stone shall take account of:
climatic conditions in the area of the work;
mechanical strength, weathering and chemical resistance.
The stone for masonry shall be stronger than the mortar or concrete for binding. The shear strength of mortar, normally hardened, must be approximately equal to the tensile strength and 1/10 of the compression strength.
Taking in account the shape, dimensions and finishing degree, the stone masonry may be:
rubble stone masonry;
hewn stone masonry (rough hewn quarry stone, dressed quarry stone, polygonal stone) composite material.
The above shall correspond to STAS 5089-71.
1.13.2 Construction of rubble stone masonry
Rubble stone masonry shall be of quarry stone or pebble stone, of irregular shape, hammered to remove the earth, weathered soft parts and pointed edges.
Mortar shall be cement mortar to STAS 1030-85, according to the nature of the works.
Rubble stone may be used for bearing walls, pitching, side ditches according to the design and to STAS 2917/79.
1.13.3 Hewn stone masonry
The exposed face of the quarry stone shall be roughly hewn, with the edges approximately parallel. The side faces shall be hewn by hammer as per STAS 2917/79.
The weight of the stone blocks shall be about 20 kg to be handled by a single workman.
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Heavier stone blocks shall be handled by lifting devices.
Mortars for construction of stone masonry shall fulfil the technical conditions of STAS 1030/85 and other valid technical regulations concerning the mix formula of mortars for masonry.
Masonry works shall be according to provisions of STAS 2917/79.
The pitching of dressed quarry stone, polygonal stone shall be stone of regular shape. The stones shall have no defects such as holes, cracks, clay inclusion and must have a neat visible face.
Dressed quarry stone pitching shall be with a rectangular face, regularly hewn facing. The dimensions of the dimensions of the dressed stone shall observe STAS 2917/79.
The facing shall be finished by coarse or fine scabbling, bush hammering, and scraping, according to the provisions of the design.
Masonry joints shall be 2-5 mm thick and the cement mortar shall be of mark 100 STAS 1030/85.
1.13.4 Control and acceptance of stone masonry
Control and acceptance of stone masonry shall be as follows:
materials compliance;
construction tolerances;
expansion and settlement joints are correctly positioned;
the evenness of facing;
the quality of finishing.
Tolerances shall be as per C 193/79 "Technical regulations for the construction of stone masonry" as follows:
permissible deviation from the vertical ± 20 mm for every 4 m of height but no more than ± 30 mm on the entire height;
permissible deviation horizontally 20 mm for a length of 10 m.
1.14 GUNITING
1.14.1 Materials used for guniting
1.14.1.1 Cement
Portland cements or composite cements according to SR 388 - 95 and SR 1500/1996, taking into account of the provisions from the Section 10 - Concretes shall be used for guniting.
Cement transport, storage and quality control shall be done according to the Practice Code NE 012/99.
Testing procedures shall be as per SREN 196/1-95, SREN 196/3-97, SREN 196/7-95, and SR 227/2-94.
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1.14.1.2 Aggregates
To prepare mortar and concrete (with apparent density between 2000 - 2500 kg/cu.m) for guniting, natural crushed aggregates shall be used.
To prepare mortar for guniting only sand with maximum 5 mm grains shall be used and to prepare concrete for guniting, sand 0 - 3 mm and aggregates 7, 10 or 16 mm shall be used, depending on the conditions and equipment used.
Aggregates must fulfil the conditions of STAS 1667/76, annex IV.3.
Aggregates used for the preparation of gunited concrete shall be as follows:
Max. dimension of Limit Passes in % through sieve of the diameter aggregate (mm) 0,2 1 3 5
3 mm bottomtop
1020
6075
100100
--
5 mm bottomtop
818
4560
7085
100100
Aggregates used for preparation of gunited concrete shall fulfil the following conditions:
Max.dimensionof aggregate
(mm)Limit
Passing % through sieve of diameter
0,2 1 3 5 7 10 16
7 mm bottomtop
616
3045
6580
--
100100
10 mm bottomtop
515
2540
5065
6580
--
100100
16 mm bottomtop
515
2035
4055
--
6580
--
100100
The moisture content of aggregates used for preparation of gunited concrete or mortar shall be of 6 - 8%.
1.14.1.3 Additives
Additives may be used in order to prepare mortar and concrete for guniting.
Powder additives shall be added during mixing.
Liquid additives shall be mixed with water.
1.14.2 Mortar and concrete guniting
Only approved machines for guniting shall used.
In order to ensure a uniform jet of guniting, a constant compressed air flow suited to the machine is necessary.
After finishing the work, the guniting machine shall be emptied and cleaned together with all pipes and nozzles by washing with water and blowing with compressed air. Special attention shall be paid to cleaning the nozzle and orifices without causing damage.
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In order to ensure a uniform consistence of the gunite, the water supply shall be at the correct flow and pressure to suit the machine.
To prepare dry guniting admixture mechanic means shall be used. The mixing time shall be established so that a homogeneous admixture is obtained.
Admixture haulage from the place of preparation to the guniting machine shall be as short as possible so that the admixture is not altered.
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1.14.3 Mortar and concrete applied by guniting
Determination of the composition of mortar and concrete to be applied by guniting consists of establishing the aggregate grading and the cement dosage. Water is added to the mortar or cement as the dry mixture leaves the nozzle so that a homogeneous stable mixture results. Dosage shall be made gravimetrically.
The cement quantities used for preparing mortars shall be established as indicated below.
Cement class 32,5 42,5Dimension of aggregates 0 - 3 0 - 5 0 - 3 0 - 5
Mortar mark Average quantities of mortar kg/cu.m200 450 425 425 400300 500 475 450 425400 600 575 525 500
The determination of aggregate quantity necessary for 1 m3 of mortar shall be done based on the endorsed cement dosage assuming a density of about 2100 kg/m3 and a 200 l of water.
The cement quantities used for preparing mortars shall be established as indicated below.
Cement class 32,5 42,5
Dimension of aggregates 0 - 7 0 - 10 0 - 16 0 - 7 0 - 10 0 - 16
Concrete class Average quantities of concrete kg/cu.m
C 12/15 (Bc 15) 400 380 360 375 350 325
C 18/22,5 (Bc 22,5) 450 430 410 415 400 385
C 25/30 (Bc 30) 500 525 500 480 460 440
The determination of aggregate quantity necessary for 1 m3 of mortar shall be done based on the endorsed cement dosage assuming a density of about 2300 kg/m3 and a 160 l of water.
The time taken from preparation of the mixture, to the introduction of the mixture into the guniting machine and the application of the mixture shall be less than 1 hour. The mixture storage shall be kept dry to avoid alteration or modification of the mixture.
1.14.4 The supporting surface
Where gunite is applied to a concrete support surface, the concrete support surface shall be cleaned of impurities and prepared by:
scabbling;
levelling;
washing. Before guniting, the support should be wetted in depth but dried on the surface. If necessary, decontamination of the support shall be done (removing of the sea salt, ice or fungus);
Concrete guniting shall be made shortly after support preparation.
In the case of application gunite to a brick support surface it shall be cleaned of impurities by washing with a water jet and compressed air.
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The masonry surface shall be kept wet several hours before guniting. The application of gunite shall be after drying the support surface.
In the case of application of gunite directly on stones, the stones shall be cleaned by compressed air only.
Before applying gunite the following shall be checked and recorded:
support surface cleaning, condition of the surface;
condition of the casting and conformity with the design;
correct mounting, fixing and supporting of formwork and scaffolding;
wetting and oiling of the formwork.
1.14.5 Application of mortar and concrete by guniting
Prior to guniting the consistency of the mixing shall be tested by operating the nozzle in another location to the surface to be guniting. When the correct consistency of the gunite is obtained, the nozzle shall be oriented towards the surface to be gunited.
Generally, the guniting nozzle positioning shall be perpendicular to the support surface.
The distance of the nozzle from the support surface shall be between 50 cm to 200 cm, according to the pressure at the exit of the nozzle.
The application of the guniting layers shall be done by circular movement of the nozzle around a point perpendicular to the support surface. Gunite shall be applied in a homogenous manner.
Measures shall be taken to avoid staining or dirtying the ungunited surfaces.
Reinforcement of the gunite layer shall be with mesh fixed in a sufficient number of places (min. 4 places per m2) on the support layer. The gunite layer shall totally cover the reinforcement.
Guniting shall be in at least two layers, the first layer being a priming layer.
Primer shall be of cement and sand 0 - 1 mm for mortar or 0 - 3 mm for concrete in equal parts by weight.
The next layer is applied as soon as priming is finished.
Where the required thickness cannot be obtained from the second layer, additional layers shall be applied.
Where the allowable time between applying layers is exceeded the surface shall be prepared according to the directions of the Engineer.
It is unacceptable to use a trowel for preparing the surface of the gunite. Before restarting work after the hardening of the gunite all waste/surplus material shall be removed with water and/or compressed air. Guniting shall be resumed only after the surface is dried, and a priming layer applied according to the above-mentioned provisions.
1.14.6 Surface treatment of gunite
Where the surface resulting from guniting is not acceptable, i.e. a fine surface is required; further treatment of the surface shall be made as follows:
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after finishing guniting, a fine and fluid mortar layer is applied, the guniting nozzle being kept at a bigger distance (about 1.5 m);
after about 30 minutes from the application of this guniting layer, according to the finish required, surface levelling shall made with a wooden or metallic tool.
The application of this mortar layer shall be a minimum of 45 minutes from the application of the last gunited layer.
The gunited mortar and concrete shall be protected to avoid cracking.
If, after finishing the guniting, the ambient temperature is under +5C measures for protecting the gunite shall be taken, by covering with tarpaulin. If guniting is applied during cold weather, the provisions of the C 16/84 Norms shall be fulfilled.
1.14.7 Checking of guniting works
Checking of guniting works shall be performed based on the provisions from section 17 of the Practice Code NE 012/99.
a. The main obligations of quality control during construction are:
checking the normal functioning of the guniting machine;
checking the qualifications of the guniting team;
checking the professional application of the guniting.
b) Checking of the gunited mortar and concrete quality and of their adherence to the support surface shall be done by hammering the surface. Portions that are hollow shall be removed and repaired by reguniting.
1.15 REPAIR OF DAMAGED CONCRETE
This section refers to the repair of the damaged reinforcement covering layer by appliance of special concrete and mortar.
1.15.1 Concrete
Special concrete is a slightly alkaline, super fluid micro-concrete. The basic material is Portland cement, aggregates, synthetic materials admixtures, with reduced water content at mixing. The physical - mechanical characteristics for a temperature of 200 are:
compression strength min. 30 N/mm2 at 3 days, min. 60 N/mm2 at 28 days
elasticity modulus min. 30 KN/mm2 at 28 days
adhesion resistance min. 60 N/mm2 at 28 days
The degraded concrete shall be stripped and the resulting concrete surface after stripping chiselled, brushed by a wire brush, cleared by a compressed air jet and chemically treated.
The uncovered reinforcement shall be wire brushed until it has a metallic lustre.
The concrete shall be applied by means of a trowel.
Areas repaired by special concrete shall be treated to match the surrounding surface.
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1.15.2 Mortars
Special mortar for repairing degraded concrete surfaces mainly consists of Portland cement, aggregates, filler and chemical and polymeric admixtures.
The physical-mechanical characteristics for a temperature of 200 are:
compression strength min. 10 M/mm2 at 3 days(according to BS 6319 PT. 2 – dry treatment) water uptake: max. 0.0015 at 10 minutes;(according to BD 1881 PT. 5,1970).
colour diffusion < 2 x 10-10 cm2 /sec (Tay wood method).
The degraded concrete shall be stripped and the resulting concrete surface after stripping chiselled, brushed by a wire brush, cleared by a compressed air jet and chemically treated.
Uncovered reinforcements shall be wire brushed until they have a metallic lustre.
The mortar shall be applied by means of a trowel and the fresh mortar surface smoothed by a mason’s float. The mixture for preparing the special mortar shall be delivered in bags or metal boxes on which the term of guarantee is inscribed. The mixture shall be used in accordance with the manufacturers recommendations.
Areas repaired by special concrete shall be treated to match the surrounding surface.
1.16 COATING REPAIRS
Preparatory works shall consist of:
removal of damaged concrete from the existing coating;
drilling, cleaning by compressed air, wetting, grouting, introducing iron-ties and fastening;
cleaning of the area with compressed air;
wetting of the concrete.
Concreting shall be as follows:
application of base course;
erection of formwork and reinforcement;
concreting;
removal of shuttering after 24 hours, and excess concrete carefully removed.
Commissioning of repaired concrete shall be according to NE 012/99.
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2 ROADS
2.1 EARTHWORKS
2.1.1 General provisions
This Specification applies to earthworks in public roads construction and includes the conditions to follow during the earthworks construction with regard to excavation, transport, compaction, levelling and finishing of the works, as well as the quality control and acceptance criteria.
The Contractor shall perform, in an authorised laboratory, all the tests required by the Specifications and any other tests required by the Engineer.
Apart from the Specifications, the Contractor shall comply with the stipulations of the standards and norms in force.
14 days before starting the works the Contractor shall submit for the Engineer’s approval, the Method Statement for earthwork construction and that shall include:
Detailed programme of earthworks construction
The equipment necessary for excavation, transport, spreading, watering, compacting and finishing
Borrow pits and earth storage places (temporary and permanent) and the related Method Statement and also the access to each of them.
Temporary road diversions for the public traffic during the works construction
Diagram of Earthworks Displacement.
In order to determine the details of the compaction Method Statement, trial sections shall be executed by the Contractor, on his own expense; the size and location of the trial sections shall be decided together with the Engineer.
After executing the trial section, the Method Statement shall be completed with information regarding the compacting Method Statement:
The features of the compaction equipment (weight, width, tire pressure, vibration parameters, speed)
Number of passes with and without vibration to achieve the degree of compaction according to the Technical Specification stipulations.
The thickness of the layer before and after compaction.
The Contractor shall ensure that by all procedures applied, he fulfils the requirements of the Technical Specifications.
The Contractor shall record on a daily basis data related to the construction of the works and the obtained results of measurements, samples and tests.
2.1.2 Materials
2.1.2.1 Top Soil
Topsoil “good for vegetation” shall be used to cover the surfaces that have to be seeded and planted.
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2.1.2.2 Soils for earthworks
The types of soils used for earthworks are showed in Tables 1a and 1b.
In case the soil, in the area where earthworks are to be executed, is of “bad” or “very bad quality” (see Table 1b) it shall be replaced with a suitable quality soil or it shall be stabilized either mechanically or using binders (quick lime, power plant ashes etc).
Replacing or stabilizing the earth shall be executed over the entire width of the platform with a minimum 20 cm depth for the “bad quality” soil and minimum 50 cm for the “very bad quality” soil or in case the dry density is less than 1.5g/cm3 .
Clayey soil type 4d shall be replaced or stabilized in at least 15 cm depth.
Clayey soils of “medium” quality can be used provided that the STAS 1709/1,2,3-90 stipulations regarding the prevention of deterioration caused by freezing thawing are respected.
Inorganic soils of “bad” and “very bad” quality as well as the organic soils, silts, mud, top soil, soft soils (consistency index less than 0.75) and soils containing more than 5% water soluble salts shall not be used for embankment construction.
The Contractor shall not use materials that:
are frozen;
contain organic matter in decay (grass, branches, roots).
Soil containing water soluble sulfates more than 1.9 g/l (SO3) shall not be stored or used as filling material nearby/in the proximity of the concrete works.
2.1.2.3 Water
Water used for compaction of the earthworks shall be clear and it shall not contain either inorganic or organic suspensions.
2.1.2.4 Quality control of soils
Before starting the works, the Contractor shall determine the quality and estimate the quantity of materials from the borrow pits. The documents will be submitted to the Engineer for approval.
The materials used for earthworks shall also have the Engineer’s approval before starting the works.
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Table 1a – Soil types (non-cohesive soils)
The main types of soil – name, features Type
(Symbol)
Content in fine parts in % of the total mass
Irregularity index
Un
Plasticity index for parts less than 0,5
mm Ip
Swelling capacity
UL (%)
Material quality for
earthworks<0,005 mm <0,05 mm <0,25 mm
Coarse grained:
Fraction > 2 mm is more than 50% of the mass
Boulder stones, blocks, gravel
Very few fine parts, irregular (continuous grading);
Non-sensitive to freezing thawing or to moisture content variations.
1a
< 1 < 10 < 20
> 5
0 -
Very good
Id.1a, discontinuous grading 1b 5 Very good
medium and fine:
fraction < 2 mm is more than 50% of the mass
Gravel sand, coarse grained sand, medium or fine
With fine parts, irregular (continuous grading);
Medium sensitivity to freezing thawing, non-sensitive to moisture content variations
2a
< 6 < 20 < 40
> 5
10 -
Very good
id 2a, discontinuous grading 2b 5 Good
medium and fine with cohesive soils as binding material
fraction < 2 mm is more than 50% of the mass; cohesive soils as binding material
Gravel sand; coarse grained sand, medium and fine, with mud as binding material
With very many fine parts;
Very sensitive to freezing thawing;
The fine fraction has low swelling capacity
3a
6 20 40 - > 10
40 Middling
Id 3a, the fine part has medium or high swelling capacity 3b > 40 Middling
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Table 1 b – Type of soils (cohesive)
Name and characteristics of the main type of soils Symbol Grading according to Cassagrande nomographic chart
Plasticity index Ip for parts less than 0,5
mm
Swelling capacity
UL%
Material quality for earthworks
Cohesive soils:o Dusty
sando Sandy
dusto Clayey
sando Dusty,
clayey sando Dusty clayo Dusto Dusty,
sandy clayo Sandy
clayo Clayo Fat clay
Inorganic:- C and U low- S i-d medium
4a
Plasticity Index – Ip
< 10 < 40 Middling
Inorganic:- C medium- U low or medium- S i-d very high
4b < 35 < 70 Middling
Organic (OM>5%):- C and U low- S i-d medium
4c
70
10 40 Middling60
Wc
= 50
%
4d
Inorganic:- C and U high- S i-d medium 4d
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Wc
= 30
% > 35 ≥70 Bad40 4a
Organic (OM>5%):- C medium- U medium or low- S i-d very high
4e
30 4b< 35 < 75 Bad20
4f
Organic (OM>5%):- C high- U high or medium- S i-d very high 4f
104c 4e
- 40 Very bad10 20 30 40 50 60 70 80 90 100
Flow limit- Wc (%)Diagonal: Ip = 0,73 x (Wc – 20)
Note: OM = organic matterC = compressibilityU = swelling capacityS i-d = sensitivity to freezing thawing
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Table 2 - Tests to verify the soil
No. Characteristics Minimum frequency Methods for
determination according STAS
1 Grading Depending on the irregularity of the soil, at least one test each 5000 m3. 1913/5-85
2 Plasticity limits Depending on the irregularity of the soil, at least one test each 5000 m3. 1913/4-86
3 Compaction characteristicsDepending on the irregularity of the soil, at least one test each 5000 m3..
In case of filling behind the works of art and for soils in protective layers, for each laid layer.1913/13-83
4 Irregularity index Depending on the irregularity of the soil, at least one test each 5000 m3. 730-89
5 Swelling capacity In case of filling behind the works of art and for soils in protective layers, at least one test each 1000 m3. 1913/12-88
6 Sensitivity to freezing thawing In the natural ground under the embankment and in cutting, at least one test each 250 m of road. 1709/3-90
7 Moisture content Either daily or at each 500 m3. 1913/1-82
8 Maximum dry density Depending on the irregularity of the soil, at least one test each 5000 m3. 1913/3-76
Note:
1. When approving the source for soil it is necessary to present the tests regarding the organic matter (in compliance with STAS 7107/1-76), water- soluble salts (in compliance with STAS 7107/3-74) and compressibillity (in compliance with STAS 8942/1-84).
2. The Contractor may request the Engineer’s approval for other Norms and testing methods that have Technical Agreement in Romania.
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2.1.3 Earthworks construction
2.1.3.1 Setting out
The Engineer shall hand over to the Contractor the benchmarks located outside the construction limits (at least 2 benchmarks/km) and a list indicating the coordinates of the main points of the alignment and of the benchmarks.
Before starting the works, the Contractor shall re-establish the benchmarks (if necessary) and he shall execute the setting out of the cross-section, at his own expense.
On completion of the setting out of the centre line, the Contractor shall mark on the ground the following:
height of the filling
the intersection points of the slope with the natural ground
the slope's gradient
Over the entire duration of the construction works, the Contractor shall execute, at his own expense, the maintenance of all pegs and benchmarks, including their restoration and relocation if necessary.
During the setting out all the existing utilities located either within or in the proximity of the construction limits shall be visibly marked in case it is necessary to relocate or protect.
2.1.3.2 Preliminary works
Before starting the earthworks the following shall be executed:
Tree-cutting: cutting and transport of all trees and bushes (including tree roots grubbing out and transport) to locations approved by the Engineer;
Removal of leaves, branches and grass and transport to locations approved by the Engineer
Removal and storage of the topsoil in locations approved by the Engineer;
Land drainage;
Demolition of the existing constructions.
On the sections where the surface water can discharge into the construction limits, the Contractor shall drain the water outside the construction limits, at his own expense.
These works shall be executed wherever necessary and the Contractor shall ensure adequate devices to store the water previous to discharge it.
The existing over-ground or under-ground construction located in the work area shall be demolished to a depth of 1.00 m below the foundation level. After demolition, the resulted holes will be cleaned and filled in appropriate material.
The remaining earth, ditches, collecting channels, cables and pipes, as well as any other fencing shall be removed to at least 1.00 m from the works area.
Drains, channels and existing ditches which became useless, from the construction limits, shall be sealed in order to prevent water percolation under the construction limits.
Materials resulted from demolition shall be transported to locations approved by the Engineer.
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Any voids (well, cellar and holes – including those resulted after tree roots grubbing up) shall be open, cleared and filled as follows:
If located in the works area, with suitable material for filling and then compacted to a ratio as indicated in table 4
If located outside the works area, with material similar to the surrounding soil and then compacted to the same ratio of the surrounding soil.
The Contractor shall start the earthworks only after the preliminary works have been verified and accepted by the Engineer.
The Contractor shall use only methods and equipment suitable for the type of filling material.
He is responsible to maintain in good conditions the approved materials, so that when they are laid and compacted the requirements of this Technical Specification are met.
The construction of the earthworks shall be stopped in case the requirements of this Technical Specification are not met due to the unfavourable weather. The construction of the earthworks on cold weather, below +5o C, can occur by taking special measures, stipulated by the technical norms in force (C 16-84).
Filling operations shall not be performed when the soil is frozen, contains ice or snow, or in case the moisture is not within the limits of a proper compaction.
2.1.3.3 Displacement of Earthworks
One of the targets of the displacement of earth masses is to allow the use of the material resulted from excavation as filling material for embankments. When executing the works, the Contractor shall present to the Engineer for his approval the Chart of Displacement of Earth Masses, depending on the approved soil sources.
Material in excess as well as the unsuitable soils for filling shall be transported in permanent stockpiles, to locations proposed by the Contractor and approved by the Engineer.
In case the excavated soil is not enough for filling, the additional material shall be taken from the borrow pits proposed by the Contractor and approved by the Engineer.
The Contractor shall immediately suspend the use and inform the Engineer if the quality of the soil from either cutting or borrow pit becomes unsuitable. In case of cutting, the works can be carried on by transporting the excavated material to an approved stockpile. In case of a borrow pit the authorisation for using that specific borrow pit shall be suspended. For the borrow pit the Engineer’s approval shall be requested following the initial procedure.
The transport of the soil in embankment or other storage areas shall start when a sufficient number of spreading and compacting equipment functions in that area.
2.1.3.4 Borrow pits and earth stockpiles
The location of the borrow pits and earth stockpiles, either temporary or permanent, shall be identified and proposed by the Contractor who will also request the Engineer’s approval.
The proposal shall be presented to the Engineer at least 7 days before starting the use of the borrow pits or stockpiles and it shall have enclosed the following documents:
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Report regarding the quality of the soil from the borrow pits, including the results of the laboratory tests and analysis performed;
Estimated quantity (for borrow pits);
Excavation execution chart (for borrow pits) or storage programme;
Plan for the arrangement of the area after completion of the works;
Approval of the owner regarding the use of either the borrow pit or stockpile;
Approval from the Environment Authority;
Other agreements or approvals, when necessary.
The design together with all the investigations, tests, rents and other necessary fees to exploit the borrow pits, earth stockpiles or access roads shall be on the Contractor’s expense.
During the excavation of the borrow pits, the Contractor shall respect the following:
The top soil shall be removed and stored in approved stockpiles;
The bottom of the borrow pit shall not be lower than the bottom of the water drainage ditch
The bottom of the borrow pit shall have a transverse slope of 1-3% towards the exterior as well as a longitudinal one to ensure the water drainage;
In major river flood plains, the borrow pits shall be placed downstream having a separation area of at least 4 m width from the base of slope.
The slopes of the borrow pits located alongside the road shall have a slope of 1:1.5-1:3. In case there is no road shelf between the foot of the slope and the edge of the borrow pit the slope shall be 1:3.
Excavation in the borrow pit can be carried out in succession of the slope of the cut.
The earth stockpiles shall comply with the following requirements:
In case the stockpile is near the embankment, the first 5 m of the stockpile shall meet the same requirements as for the construction of the embankment (compaction, leveling and finishing)
The height of the stockpile shall not exceed the height of the road embankment.
The location of the stockpile shall be decided in such a way that it avoids the road to be snowed up.
The borrow pits and earth stockpiles shall not either affect the stability of the existing earthworks or cause erosion due to surface or underground water. The Contractor is responsible for any injury or damage to public or private property that can be caused by the construction of the works.
The Engineer can refuse to approve the construction of the borrow pits or earth stockpiles in case they affect the landscape or the water drainage.
2.1.3.5 Cuttings
Excavation and slope construction according to the designed cross-section shall start at the same time on the entire width.
Increasing the depth of cut shall be avoided. In case it happens the cut shall be filled to the designed level, at the Contractor’s expense and according to the requirements for filling from this Technical Specification.
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Cuttings that require filling shall be closed as soon as the stage of the works in the area allows.
When excavating in soils sensitive to moisture, the works shall be progressively executed and rapid rainwater drainage shall be ensured, avoiding affects on the hydrological equilibrium of the area or the underground water level.
In case during the excavation, the Contractor observes a combination of suitable and unsuitable materials and unless otherwise specified in the Design, the Contractor shall execute the digging in such a manner that the suitable materials are separately excavated. This is to be done in order to use them for the permanent works and to avoid being contaminated by the unsuitable materials.
The Engineer can decide a way to improve the bearing capacity in case the soil discovered at the designed level does not meet both the required quality and the bearing capacity according to the Design.
Where there are significant differences regarding the type of soil towards the Design stipulations, the Contractor can forward to the Engineer for approval a proposal to change the slope's gradient.
The slope gradient for a cut of maximum 12 m depth is showed in Table 3.
Table 3 – Slope gradient
Type of soil in the cut Slope gradient
Clayey soil: generally sandy or dusty clay, clayey sands or dusts 1:1.5
Marly soils 1:1…. 1:0.5
Macroporous soils (loess and loessoid soils ) 1:0.1
Depreciating stony rocks: gradient depending on the deterioration degree as well as on the depth of the cut
1:1.5 – 1:1
Stable stony rocks (non depreciable) 1:0.1
Stable stony rocks favourably bedded 1:0.1 vertically or in cantilever
When cutting in clayey soil deeper than 12 m or under unfavourable hydrological conditions (moisture, water seepage) at any depth, the slope gradient shall be decided further to a stability analysis.
The clods, stones and unstable rocks shall be removed from the slope and stored together with the material resulted from cutting.
If during the construction of the works the Contractor observes the loss of works stability, he shall immediately suspend the works, give notice to the Engineer and take action to consolidate the works.
The bottom of the cut shall be compacted to 100% Normal Proctor degree of compaction, measured at 30 cm depth. If the soil at the designed level has not the quality and the bearing capacity required by the design, the Engineer could instruct the construction of a form layer. In this case, the upper layer of the cutting, under the form layer, shall be compacted to the 97% Normal Proctor degree of compaction.
During the construction, the slopes as well as the area above shall be frequently verified, especially after explosions and heavy or long rains in order to observe in due time any sign of stability loss.
The method statement for levelling the roadbed in stony soil shall be proposed by the Contractor and forwarded for the Engineer’s approval. The levelling shall be carried out on the Contractor’s expense.
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The Contractor shall take all the necessary action to prevent deterioration or softening of the soil excavated from the cut and that is intended to be used as filling material.
2.1.3.6 Preparation of the soil under embankment
Soil under embankment shall be compacted to 100% Normal Proctor degree of compaction measured at 30 cm depth.
In case the gradient of the soil is more than 20%, the Contractor shall execute jointing steps having a height equal to the thickness of the filling layers. The transverse slope is 4% towards the exterior.
2.1.3.7 Construction of the embankment
In case the unfavourable weather affects the quality of the embankment, established by the Technical Specifications and the legislation in force, the works shall be stopped. They shall resume after being given the Engineer’s approval and at the time the requirements for the construction of the works in compliance with the Technical Specifications are met.
Embankments shall be executed in even layers, parallel with the designed line, over the entire width of the platform and over a length according to the approved method statement.
Separation, road inequalities and moisture content variations shall be avoided.
In special case, with Engineer’s approval, the width of the earth layers can be diminished. Under these circumstances the embankment shall be constructed of more adjoining lanes. The difference in height of two adjoining lanes shall not exceed the thickness of one layer.
The material brought on the platform shall be spread and levelled to the proper compaction thickness, as it was established on the trial section and respecting the designed longitudinal section.
The surface of the foundation as well as the one of each layer shall be even and with a transverse slope of 4% towards the exterior.
In case of embankments higher than 3 m, the base can be constructed of stone or concrete blocks with a maximum size of 50 cm. After placing, the blocks shall be in-filled using earth. The thickness of the blockage layer shall be established so that the thickness of the homogenous filling above is at least 2 m.
Filling and compaction shall be realised at the proper moisture content. The Contractor shall take all the necessary action to attain the best degree of moisture content by:
scarifying and mixing;
treating with lime;
scarifying, spreading and watering.
The compaction of each layer shall be carried out according to the parameters established on the trial section, in compliance with the characteristics of the soil used.
The compaction equipment shall ensure the achievement of all the requirements for each course and type of soil.
The Normal Proctor degree shall be achieved in accordance with Table 4.
Table 4 – Degree of Compaction
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Embankment areas intended to compactNon-cohesive
soilCohesive
soila) The first 30 cm of natural soil under embankment, with the height: h 2,00 m h > 2,00 m
10095
9792
b) In the embankment, at a depth under the roadbed: h 0,50 m 0,50 < h 2,0 m h > 2,0 m
10010095
1009792
c) In the cut, at 30 cm depth the roadbed 100 100
The Contractor can request the acceptance of a layer when in all measured points, the degree of compaction is either equal to the required level or more.
The minimum frequency of the tests shall be in compliance with the Table 5.
Table 5 – Frequency of the tests
Test Minimum frequency Observations
Optimal compaction moisture content (Proctor test)
each 5000 m3 For each type of soil
Moisture content 6 tests for each 2000 m2 of platform On each earth layer
Degree of compaction 6 tests for each 2000 m2 of platform On each earth layer
Sections and slopes
The works shall be executed so that after compaction and cleaning, the slopes are within the allowed limits. The section of the slope shall be realised without refilling.
The slope gradient depends on the type of soil used for embankment as well as on the type and bearing capacity of the soil underneath the embankment.
The gradient of the slope shall be 1:1.5, with a maximum height as indicated in Table 6.
Table 6 – The height of the embankment
Type of material used for embankment H max. (m)
Dusty or sandy clay 6
Clayey sands or clayey dust 7
Sands 8
Gravel or ballast 10
In case there are differences between the materials indicated in the Design and those stipulated by STAS 2914-84, Table 1a and 1b, the Contractor shall present to the Engineer for approval, a proposal based on field investigations, to change either the gradient or the height of the slope.
The gradient of the slope will be verified after compaction and finishing.
The embankments up to 12 m height shall have the gradient of the slope 1:1.5 for the height indicated in Table 6, measured from the roadbed downwards and 1:2 for the remaining height to base.
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For the embankments higher than 12 m as well as for those in major river flood plains, valley, puddles or swamps, with the foundation of fine or very fine soils, the gradient of the slope shall be decided based on a stability calculation. In this respect a stability factor of 1.3-1.5 shall be taken into account, according to STAS 2914-84 and Table 7 shall be also followed.
Table 7 – Maximum height of the embankment depending on the characteristics of the foundation soil
The gradient of the foundation
a) internal friction angle (grade )5 10 15
b) material cohesion (Kpa)30 60 10 30 60 10 30 60 80
Maximum height of embankment hmax (m)0 3,00 4,00 3,00 5,00 6,00 4,00 6,00 8,00 10,001:10 2,00 3,00 2,00 4,00 5,00 3,00 5,00 6,00 7,001:5 1,00 2,00 1,00 2,00 3,00 2,00 3,00 4,00 5,001:3 - - - 1,00 2,00 1,00 2,00 3,00 4,00
Embankments of water sensitive soils
When preparing the Method Statement, the Contractor shall include special measures that have to be taken into account in case of water sensitive soils, such as:
laying and scarifying the soil;
lime treatment;
construction of open drains.
Stony embankment
When utilised for embankment, the stony material shall be spread in layers and levelled to obtain a homogenous mixture with a minimum content of voids.
The thickness of the layers shall be established in compliance with the material size and the capacity of the compacting equipment, but it shall not be more than 80cm. The last 30cm underneath the roadbed shall not contain blocks with the maximum size more than 20cm.
In case voids still remain after compaction, the layer shall be completed with an approved grain material so that all the surface voids are filled.
In case of uncovered slopes, the blocks shall be fixed over at least 2/3 of their thickness.
Back filling of the structures (retaining walls, abutments, wing walls, etc)
Unless otherwise specified than in the Technical Specifications, the back filling of the structures shall be executed using the same material as for the embankment, apart from the stony material. The maximum size of the material that can be used is 1/10 of the filling width.
The filling shall be executed in even layers with a thickness of maximum 25cm.
The filling shall be mechanically compacted until the degree of compaction according to Table 4 is achieved.
Protection against water action
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The Contractor shall ensure the protection of embankments against erosion caused by rainwater (the heaviest rain in the last 10 years shall be taken as reference).
2.1.3.8 Ditches and Gutters
Ditches and gutters shall be constructed parallel with the base of the slope.
2.1.3.9 Roadbed finishing
The roadbed shall be compacted, levelled and finished respecting the level, slope and width stipulated in the Design.
The Contractor shall limit the access of all equipment on the roadbed after the finishing procedure.
2.1.3.10 Protection with top soil
The slopes that are to be covered with topsoil shall be previously either cut in steps or reinforced with a grid made out of furrows and wattles or pre-cast units.
After having been covered with topsoil, the slope shall be fertilised and seeded.
After sowing, the slopes will be watered several times until the grass seeds start the vegetation process.
During the growing season, the grassy slopes shall be mowed twice a year. The cut grass shall be collected and removed to locations approved by the Engineer.
2.1.4 Control of construction and acceptance of works
2.1.4.1 Control of Construction
The quality control of earthworks includes:
Verifying the sitting out;
Verifying the quality, condition and preparation of the foundation soil;
Verifying the quality and the condition of the earth used as filling material;
Control of the characteristics of the executed layers;
Control of the characteristics of the road platform.
The Contractor shall not start the construction of any layer before the previous layer is completed, verified and accepted by the Engineer. The Contractor shall ensure, at his own expense the maintenance for the accepted layers before the next layer is laid.
The acceptance of each layer shall be again requested in case there are more than 7 days from the date of the initial acceptance and the construction of the next layer. It is also compulsory when within this period of time the Engineer considers that the accepted layer does not meet the requirement to be covered.
The deflection measurement shall be performed using a lever deflectometer, according to Norm CD 31-94.
The minimum frequency to check the degree of compaction shall be as indicated by Table 5.
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Checking the quality of soils means determining their characteristics, according to Table 2.
The Contractor can propose the use of alternative tests but they can be considered only if approved by the Engineer.
Checking the pegging out
The construction of earthworks can start only after the sitting out has been verified and approved by the Engineer.
The allowed limits in the pegging out are 50 mm.
Checking the characteristics of the foundation soil
To verify the quality of the foundation soil, sampling shall be performed from the working area. There shall be 3 samples for each 100m of road length distributed in such a way that the entire working area is verified.
The analysis and tests shall be performed according to Tables 1 and 2.
Deflection measurement shall be performed in cross-section on 6 strips (4 traffic lanes and 2 emergency lanes), wherever it is necessary, but at least on each cross-section of the design.
The bearing capacity of the foundation layer is considered achieved when the value of the elastic deformation, measured according to the stipulations of norm CD 31-94, is less than the allowed on from Table 8 in at least 90% of the measurement points and is less than 600 1/100 mm in the other measurement points.
The performance uniformity is considered as satisfactory if the coefficient of variation is < 50%.
Table 8 – Elastic deformation limits
Type of soil according to STAS 1243-88 Elastic deformation limit (1/100 mm)
Dusty sand, Clayey sand 350
Sandy dust, Sandy-clayey dust, Clayey dust, Dust 400
Dusty clay, Sandy clay, Dusty-sandy clay, Clay 450
To verify the degree of compaction for the foundation soil, the indications of tables 4 and 5 shall be respected and a correlation with the points where a low bearing capacity is observed shall be made.
The tolerance for the embankment construction limits is +50 cm.
Verifying the features of the executed layers
The following determinations shall be performed on the compacted layers:
Degree of compaction – on each layer, in cross-section, minimum 6 tests/2000m 2 of layer, according to STAS 2914-84. In case of cohesive soils, from each point 3 samples shall be taken (surface, middle and base) if the thickness is more than 25 cm and 2 samples (surface and base) for less than 25 cm thickness. In case of non-cohesive soils 1 sample shall be taken from each point on the middle of the layer.
Thickness and cross section slope of the layer – for each layer
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Deflection measurement – every third layer or after rain or at the last layer
The measurement shall be performed in cross-section at a maximum distance of 25 cm on 6 strips.
The values for the degree of compaction are given in Table 4.
The slope of the cross-section after compaction shall be 4%, having a tolerance of ± 1%
The control of the roadbed features
The control of the roadbed features involves survey and deflection measurements, at the level of the roadbed and on the achieved degree of compaction.
The dimensions and the roadbed level are measured wherever necessary but, in the designed cross-sections at least.
The related allowed limits for the roadbed are as follows:
Width: 5 cm from the road centre line; 10 cm over the entire road platform;
Level: between +2.5 and –5.0 cm.
The transverse slope of the roadbed after compaction shall be 4%, having a tolerance of ± 1%.
The elastic deformation is measured wherever necessary, on 6 strips in cross-section, but at least in the designed cross-sections.
The bearing capacity of the roadbed shall be achieved when the value of the measured elastic deformation is lower than the allowed value according to the Table 8.
The control of the roadbed features and the overall verification of the executed earthworks (dimensions and the uniformity of the roadbed surface and slopes) shall be performed at the same time.
The allowed limits of the uniformity of the roadbed surface and slopes, measured using the "3 m straight edge" are according to the Table 9.
Table 9 – Surface uniformity
Section2.1.4.1.1 Limits
Compact rocks Non compact rocks or soils
Platform without improved form layer 5 cm 3 cm
Platform with improved form layer (*) 10 cm 5 cm
Uncovered slope - 10 cm
Note (*) – when it is intended to execute improved form layer over the platform.
2.1.4.2 Acceptance of Works
After the works are completed on a road section they will be subjected to Engineer's approval before the next layer could be laid.
To verify the works that are to be covered, it shall be previously established whether they are executed in accordance with the Design as well as with this Technical Specification.
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After this procedure an Acceptance Report shall be concluded to further authorise the Contractor to proceed to the next construction stage.
The Engineer establishes the construction stages subject to acceptance in the Programme of Acceptance for construction stages, which is enclosed in the Working Drawings and refers to the following:
sitting out;
the level and the final section in case of excavation;
the nature and compaction of the foundation soil;
in case of embankment, for each course after compaction.
2.2 LAYER OF BALLAST OR OPTIMAL BALLAST MIXTURE
2.2.1 General provisions
The Technical Specifications apply when constructing the ballast and optimal ballast foundation courses of the road structure. It comprises the technical conditions to be met by the materials utilized, provided in STAS662-2002 as well as the requirements for the constructed ballast foundation according to STAS 6400-84
The Contractor shall perform, in an authorized laboratory, all the tests and determinations requested by the Technical Specifications as well as any other test requested by the Engineer.
Apart from the Technical Specifications, the Contractor shall comply with the stipulations of the standards and norms in force.
The Contractor shall present for the Engineer’s approval, the execution method statement, 7 days before commencing the works. This has to include:
Execution schedule for the foundation course;
The equipment used for aggregate production and transportation
The equipment used for optimal mixture production;
The equipment used for extraction, transport, spreading, watering, compaction and finishing of the optimal mixture;
The sources (ballast pits or suppliers) and aggregates stockpiles, including the access to each.
To establish the details regarding the compaction method statement, the Contractor shall execute trial sections. Their size and location shall be established by common agreement with the Engineer.
After completion of the trial sections, the construction method statement shall be completed with information regarding the compaction method statement such as:
Characteristics of the compaction equipment (weight, width, tire pressure, vibration characteristics, speed);
Number of passes with and without vibration to attain the degree of compaction in compliance with the stipulations of the Technical Specifications;
The number of the sub-layers where the foundation course shall be performed (when the compaction level cannot be achieved by laying one course);
The thickness of the ballast/optimal ballast course before and after compaction.
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The Contractor shall make sure that by all applied procedures he meets the requirements of the Technical Specifications.
The Contractor shall record on a daily basis data regarding the execution of the works, as well as the results of measurements, tests and investigations.
The Contractor shall perform supplementary examinations, whenever required by the Engineer.
2.2.2 Materials
2.2.2.1 Natural aggregates
To execute the ballast or optimal ballast foundation course the Contractor shall use either natural ballast or optimal ballast prepared of natural aggregate types, which have the characteristics indicated in Table 1.
The aggregates shall come from stable rocks, which are not affected by water, air or frost and shall not contain visible foreign matter (clods, coal, wood or vegetation residue) or any other materials.
Each source of aggregates (natural ballast or sorts for optimal ballast) shall be proposed by the Contractor and submit for the Engineer’s approval.
The proposal shall be submitted to the Engineer at least 7 days before opening the ballast pit or commencing the supply and it shall have enclosed the following:
report upon the quality of the aggregates, which has to include the results of the laboratory tests and analysis performed. The tests shall be conducted according to Table 1 and the stipulations of SR 662-2002 (Table 19);
analysis of the conformity in relation with the stipulations of the Technical Specifications;
estimated quantity;
chart showing the manner the ballast pit is to be exploited or a graph indicating the supply;
transport route;
lay-out of the storage place
lay-out for the arrangement of the area after completing the exploitation (in case of the ballast pit) or the stockpile;
agreement of the owners regarding the possession and exploitation of the area
agreements, approvals and authorisations required by the legislation in force.
All the investigations, tests, rents and taxes related to the exploitation of the ballast pit shall be at the Contractor’s expense.
The ballast pits and stockpiles shall not affect the stability of the existing earthworks and shall not cause erosion by the effects of surface or underground water. The Contractor is responsible for any injury or damage to public or private property that can be caused by the execution of the works.
The transport and the storage of the aggregates from different sources shall be such that it avoids contamination or mixing of the aggregates. The access roads to the stockpiles shall be arranged in order to avoid the contamination of the aggregates with mud or other materials.
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The aggregates shall be stored on organized platforms, which shall have slopes and gutters for water drainage. Mixing or contamination of the stockpiled aggregates should be avoided. The aggregates stockpile shall be identified by panels, which indicate the source and the size.
The Contractor shall ensure a temporary storage area for the rejected aggregates. In case of ballast extracted from below the water level, the Contractor shall provide the necessary surfaces for temporary storage, until excess water has drained away.
Aggregates that exceed 1,9 g of sulphate (SO3 ) / l, shall not be stored or used as filling material in the proximity of the works that contain cement (concrete or stabilized ballast); the minimum distance from these works shall be of 1 m.
Table 1 – Aggregates characteristics
Characteristics Limits
STASBallast Optimal ballast
Sort 0-63 0-63 -
Fraction content %: < 0,02 mm
< 0,20 mm
0 - 1 mm
0 - 4 mm
0 - 8 mm
0 - 16 mm
0 - 25 mm
0 - 50 mm
0 - 63 mm
max. 3
3-18
4-38
16-57
25-70
37-82
50-90
80-98
100
max. 3
4-10
12-22
26-38
35-50
48-65
60-75
85-92
100
4606-80
Grading Fig. 2 SR 662 Fig. 2 SR 662 4606-80
Non-uniformity coefficient (Un), min. 15 730-89
Sand equivalent (EN), min. 30 30 730-89
Los Angeles factor, %, max. 50 30 730-89
Optimal ballast shall be prepared by mixing the sorts 0-8, 8-16, 16-25, 25-63, according to SR 662.
After organizing the stockpiles, they will be approved by the Engineer. The checking of the aggregates from a stockpile shall be performed according to Table 2.
Table 2 – Tests on aggregates
Action, verifying procedureor characteristics to verify
Minimum frequency when supplying
Method to determine (STAS)
Examination of data recorded in the quality certificate
Each transport-
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GradingSand equivalentIrregularity
One sample for each 400 t730-894606-80
Wearing resistance (Los Angeles test) One sample for each 5000 t 730-89
2.2.2.2 Water
The necessary water to correct the moisture shall be clear, with no particular taste or smell and it shall not contain either inorganic or organic suspensions.
2.2.3 PREPARATION OF OPTIMAL BALLAST
2.2.3.1 Optimal ballast preparation plant
The plant shall have the following equipment and facilities:
Separate storage areas of aggregates on concrete platforms with slopes for water drainage; the platforms shall have vertical separators to avoid mixing of aggregates. Each storage area shall indicate the type of the aggregate;
Devices to measure and store the aggregates;
Adequate equipment to prevent segregation of the mixture when unloading in the transport vehicles
Authorized plant laboratory;
Facilities for the workers safety and equipment for fire extinction.
Installations and materials for cleaning the measurement and mixture devices, the bunkers and the means of transportation.
The aggregates shall be measured according to the grading. The following limits shall be respected in this case:
Aggregates 3%;
Water 2%.
After installing, checking and obtaining all the authorisations required by the authorities, the plant shall be submitted to the Engineer’s approval.
All the expenses related to the plant authorization and function shall be the Contractor’s responsibility. During the Plant function the Contractor, on his own expense, shall ensure the necessary checking in order to produce the mixture with the approved characteristics.
2.2.3.2 Preparation of the mixture
Before starting the works, the Contractor shall perform tests on the Plant in order to confirm the mix proportion, as determined in the laboratory.
These tests shall also establish the minimum duration for the mixing operation, which ensures the homogeneity of the mixture.
Any change of the mixture ratio, apart from the correction imposed by the humidity of the stored aggregates, shall be treated as a change of the job mix formula and submitted for the Engineer’s approval.
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The necessary quantity of water shall be decided according to the aggregate humidity, taking into account the water loss during transportation from the Plant to the working area.
2.2.3.3 Quality control of the mixture
The sampling and the quality control of the mixture shall be performed according to Table 3.
Table 3 - Tests performed on the Plant
Activity, verifying procedure or characteristics to verify
Minimum frequency on the PlantTesting method
The optimal compaction moisture content (Modified Proctor test)
Each study of the job mix 1913/13-83
Grading content of the mixture At least once a day for each 500 m3 4606-80
Aggregates humidity (1)At least once a day when the weather condition change
1913/1-82
Note: 1 – to establish the necessary water content of the mixture.
The tolerances when preparing the mixture are:
type 0-8 mm 5%;
type 4 mm 2%
For the other types, no tolerances are admissible.
In case of natural ballast, the transport, storage and control shall be performed under the same conditions as per the optimal ballast.
2.2.4 CONSTRUCTION OF THE FOUNDATION COURSE
2.2.4.1 Trial section
To establish the construction method statement, the equipment and devices necessary to lay and compact the foundation, the Contractor shall execute, with the Engineer approval and before starting the works, one trial section for each source of aggregates. The trial section shall be of at least 50m length and at least half of the platform’s width.
The laboratory on site shall decide the quantity of water that has to be eventually added in order to obtain the best humidity for compaction. The water shall be added by sprinkling, so the mixture has the optimum humidity of compaction, uniformly spread in the mixture.
The tolerances regarding the mixture humidity are more than 1% and less than 2% comparing with the best humidity level.
The compaction characteristics of the ballast for the foundation course shall be decided based on the Modified Proctor test, in compliance with the stipulations of STAS 1913/13-83:
max.PM = maximum dry density (g/cm3);
W opt.PM = optimum humidity for compaction (%).
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The preparation and execution of the works as well the measurements performed on the trial section shall be carried out under the Engineer’s supervision.
The preliminary works, their execution and the measurements on the trial section shall be performed at the Contractor expenses.
The test results from the trial section approved by the Engineer shall be used as a reference document for the completion of the method statement.
2.2.4.2 Preliminary conditions
The construction of the ballast foundation SHALL start only after the earthworks in the subject area, including the form layer or foundation sub-grade (if the case) as well as the water drainage (transverse and longitudinal drains, gutters and ditches) have been accepted by the Engineer.
To allow the water drainage from the foundation course, the bottom of the layer shall be minimum 15 cm above the maximum level of the water in the adjacent gutters/ditches, temporarily formed for draining the water during construction.
It is forbidden to stove ballast or optimal ballast from different stockpiles in the same working area.
In case of using different ballast sources, the section limits and the used sources shall be named in the Site Diary.
2.2.4.3 Transport
The Contractor shall take all the necessary action so that during transport to the working area, the ballast/optimal ballast does not significantly modify its content (segregates, either decrease or increase the water and fine parts content).
2.2.4.4 Construction
The foundation course can be laid only with the Engineer’s approval and when the roadbed meets the requirements for being covered.
The ballast/optimal ballast shall be laid over the accepted earthworks, in one or more layers depending on the thickness specified in the Design and the best thickness for compaction, as established in the trial section.
The Contractor shall not start the execution of any layer before the previous one is verified and accepted by the Engineer. The Contractor shall ensure, on his own expense, the necessary maintenance for the accepted layers construction of the next layer.
The acceptance of each layer shall be again requested in case there are more than 7 days from the date of the initial acceptance and construction of the next layer. It is also compulsory when within this period of time the Engineer considers that the accepted layer does not meet the requirement to be covered.
Compaction shall be executed as soon as possible after the material is laid and in compliance with the requirements of the construction method statement as agreed after construction of the trial section.
The characteristics of the compaction shall be established using samples taken from the work:
ef = effective density (g/cm3);
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W ef = effective humidity for compaction (%).
ef
Degree of compaction gc = -------------- x 100 max.PM
In the working area where the foundation course is not executed over the entire width of the platform, the shoulders shall be completed and compacted at the same time with the execution of the foundation course, so that the shoulders permanently frame the foundation.
To avoid accidental damage, the Contractor shall take all the necessary action to limit the traffic over the compacted and finished course.
The foundation course shall not be laid when:
the humidity of the ballast is outside the limits, as specified in III.3;
the ballast is frozen or contains ice;
the weather conditions determine that the roadbed/improved sub-grade (if the case) does not meet the requirements for covering.
2.2.5 Control and acceptance of the works
The tests performed during the execution of the foundation course shall be in compliance with Table 4.
Table 4 – Tests for the quality control
Determination; verifying procedure or characteristics to verify
Minimum frequency at the working point
Verifying method (STAS)
Examination of transport documents each transport -
Modified Proctor test For each source or when changing the grading content
1913/13-83
Determination of the compacted layer thickness
Minimum 3 determinations each
2000 m2 of foundation-
Characteristics of compaction
Humidity
Density
6 sample each 2000 m2 of laid course
1913/1-82
1913/5-85
12288-85
Determination of the degree of compaction (by determining the dry volume weight)
Daily, minimum 6 points
for each 2000 m2 of laid course
1913/15-75
12.288-85
Determination of the bearing capacity at the upper level of the layer
In cross-section, every 25 m, on one strip for each lane, including emergency stationery
Norm
CD 31-94
The bearing capacity at the upper level of the ballast layer shall be established by measurements using the lever deflectometre, in compliance with the “Technical Instructions” CD 31-94.
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2.2.5.1 Verifying the horizontal geometry
The thickness of the foundation course shall be verified wherever necessary but in at least 3 points for 2000 m2 of executed foundation. The tolerance is 20 mm.
The width of the course is measured wherever necessary but at least in every designed cross-section.
The tolerance, measured from the centreline, is +5 cm.
The transverse slope of the foundation is equal to the road revetment slope, which is indicated in the Design and it shall be measured wherever necessary, but every 25 m at least. The tolerance is 0,4% of the designed transverse slope.
The levels of the course are measured wherever considered necessary, but in every designed cross-section at least; the tolerance is 1 cm.
2.2.5.2 Verifying the compaction and the bearing capacity
The foundation course shall be compacted until the 100% Modified Proctor (MP) is achieved for at least 95% of the measuring points and 98% MP for all the measuring points.
The bearing capacity at the upper level of the foundation course is achieved when the value of the deformability measured according to the stipulations of Norm CD 31-94 is lower than 180 1/100 mm.
The uniformity of the execution is acceptable when the value of the variation coefficient is below 35%.
2.2.5.3 Verifying the characteristics of the course surface
Verifying the irregularities of the foundation surface shall be done with the 3m straight edge, as follows:
In long section, measurements shall be performed wherever considered necessary, but in the axis of each traffic lane at least; the allowed irregularities measured under the 3 m straight edge are 2 cm;
In cross-section, measurements shall be performed wherever considered necessary, but in the designed cross section at least; the allowed irregularities measured under the 3 m straight edge are 1 cm;
2.2.5.4 Acceptance on execution stages
After completing the works on a road section and before starting the next layer it will be necessary to obtain the Engineer’s approval.
The inspection of the works, which are subject to covering restrictions, shall decide whether the works have been carried out according to the Design and the Technical Specifications.
The acceptance of the works implies the checking of the records during the execution of the works and of the test results as well as the examination of the works.
After checking an acceptance report has to be completed, which authorizes the Contractor to proceed to the next construction stage.
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2.3 CRUSHED STONE OR CRUSHED STONE OPTIMAL MIXTURE COURSE
2.3.1 General provisions
The Technical Specifications refers to the construction and approval of the crushed stone or crushed stone optimal mixture foundation course of the road structure for the public roads and streets. This document includes the technical conditions which have to be met both by the materials used and the constructed foundation course.
For this project, the ballast foundation course is also the lower foundation course for the crushed stone course, according to STAS 6400-84. Therefore, no additional ballast layer (minimum 10 cm thick) shall be performed for the crushed stone foundation course.
According to STAS 6400-84 the large crushed stone 63-80 and crushed stone optimal mixture foundation course consist of two layers (lower and upper) of large crushed stone or crushed stone optimal mixture having the minimum designed thickness of 10 cm (lower layer) and 12 cm (upper layer).
On the area where the construction of a sub-base course or any other measures to improve the foundation soil are not provided, and in case the foundation soil is of cohesive soils, the lower crushed stone layer shall be exclusively constructed over an insulating layer. This layer may be either 7 cm (after compaction) of sand or geo-textile.
The Contractor shall present for the Engineer’s approval, the Method Statement, 14 days before commencing the works. This shall include:
Program of Works for the foundation course;
The equipment used for production and transport of aggregates;
The equipment used for transport, spreading, watering, compaction and finishing;
The sources (quarries or suppliers) and aggregates stockpiles, including the access to each.
To establish the details regarding the Method Statement, the Contractor shall construct trial sections. Their size and location shall be decided by common agreement with the Engineer.
After the construction of the trial sections, the Method Statement shall be completed with information regarding the compaction technology such as:
Characteristics of the compaction equipment (weight, width, tire pressure, vibration characteristics, speed);
Number of passes with and without vibration to attain the degree of compaction in compliance with the stipulations of the Technical Specifications;
Number of the sub-layers of the foundation course (when the required compaction degree could not be achieved by the construction of a single layer);
The thickness of the ballast/optimal ballast course before and after compaction.
The Contractor shall perform, in an authorised laboratory, all the tests and determinations required by this Technical Specifications as well as any other tests requested by the Engineer.
Apart from this Technical Specifications, the Contractor shall comply with the stipulations of the standards and norms in force.
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2.3.2 MATERIALS
2.3.2.1 Natural aggregates
For the construction of the crushed stone foundation the following aggregates shall be used:
a. For foundation of large crushed stone, 63-80:
sand 0-4 mm for the insulating sub-layer if no form layer is performed;
ballast 0-63 mm in the lower layer;
crushed stone 63-80 mm;
split stone 16-25 mm to wedge on the upper layer;
grained sand or grit 0-4 mm as protective material.
b. For the foundation of crushed stone optimal mixture 0-63 mm:
sand 0-4 mm for the insulating sub-layer if no form layer is performed;
crushed stone optimal mixture 0-63 mm.
Aggregates shall be from stable rocks, which can not be affected by water, air or freeze and shall not contain visible foreign matter (clods, coal, wood or vegetation remains) or other materials.
The aggregates from feldspar rocks or schist shall not be used.
Each source of aggregates proposed by the Contractor shall be submitted for Engineer’s approval.
The proposal shall be submitted to the Engineer at least 14 days before commencing the supply or the extraction and it shall have enclosed the following:
report about the quality of the aggregates, which has to include the results of the laboratory tests and analysis performed. The tests shall be conducted according to Table 1, 2, 3 and 4 and the stipulations of SR 662-2002 and SR 667-2001;
analysis of the conformity in relation to the stipulations of this Technical Specification;
estimated quantity;
chart showing the manner the exploitation that is to be carried out or a graph indicating the supply;
transport route;
lay-out of the storage area
lay-out for the arrangement of the area after closing the extraction (in case of the ballast pit) or the removal of the stockpile;
agreement of the owners regarding the possession and exploitation of the area;
agreements, approvals and authorisations required by the legislation in force;
Design and agreements for the technological roads.
All the investigations, tests, rents and taxes related to the extraction of the aggregates shall be at the Contractor’s expense.
The Contractor is responsible for any person put in jeopardy, injury or damage to public or private property that can be caused by the extraction, transport or storage of the aggregates.
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The transport and the storage of the aggregates from different sources shall be that it avoids contamination or mixing of the aggregates. The access roads to the aggregate stockpiles shall be arranged in order to avoid the contamination of the aggregates with mud or other materials.
The aggregates shall be stored on organised platforms, of concrete or asphalt mixture, which shall have slopes and gutters for water drainage. It shall be also avoided to contaminate or mix the aggregates from the stockpile. The aggregates stockpile shall be identified by panels, which indicate the source and the size.
The Contractor shall ensure a temporary storage area for not accepted aggregates.
Table 1 - SAND (insulating layer) - Conditions for acceptance according to SR 662
CHARACTERISTICS Conditions for acceptance for:
Sort 0 - 4
Grading Continuous
Fraction content (less than 0,1 mm) %, max. 14
Reversed Filter Condition 5 d15 p < d15 f < 5 d85 p
Permeability coefficient (K), cm/s, min. 6 x 10-3
Table 2 - BALLAST – Admissibility Conditions according to SR 662
Characteristics Limits
Sort 0-63
Fraction content %: < 0,02 mm< 0,20 mm0 - 1 mm0 - 4 mm0 - 8 mm0 - 16 mm0 – 25 mm0 - 50 mm0 - 63 mm
max. 33-184-38 16-5725-7037-8250-9080-98100
Grading According to figure 2 from SR 662
Non-uniformity coefficient (Un), min. 15
Sand equivalent (EN), min. 30
Los Angeles wearing resistance, %, max. 50
Note: When approving the source all the results according to SR 662 (Table 19) shall be presented.
Table 3 – CRUSHED STONE – Admissibility Conditions according to SR 667
SortCharacteristics
Grit Crushed stone (split) Large crushed stone
Limits
0-8 8-16 16-25 25-40 40-63 63-80Grains content that:- remain on the upper sieve (dmax),%, max.
5 5 5 510 10 10
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SortCharacteristics
Grit Crushed stone (split) Large crushed stone
Limits
0-8 8-16 16-25 25-40 40-63 63-80
Content of decayed, soft, porous and with voids grains, %, max.
- 10 10 -
Grain shape:- physically shape characteristic, %, max.
35 35 35
Impurity coefficient:- foreign matter, %, max.- fraction under 0,1 mm, %, max.
1 1 1 1
- 3 It is not the case
Wearing resistance (Los Angeles test) %, max. 30According to the type of
rock, (SR 667)Resistance to repeated action of natrium sulphate (Na2S04) 5 cycles, %, max.
- 6 3It is not the
caseNote: When approving the source all the determinations according to SR 667 (Table 12) shall be presented.
The crushed stone optimal mixture shall be prepared by mixing the sorts 0-8, 8-16, 16-25, 25-40 and 40-63, or directly from crushing, in case the conditions specified in Table 4 are met.
Table 4 – CRUSHED STONE OPTIMAL MIXTURE – Admissibility Conditions
Characteristics Conditions for acceptanceSort 0-63Fraction content, %, max. :- less than 0,02 mm- less than 0,2 mm- 0...8mm-20 ... 63 mm
< 34.. .1030. ..45 25. ..45
Grading Within the limits of table 5Sand equivalent (EN), min. (1) 30Activity coefficient (2) 1.5 / 2Wearing resistance (Los Angeles test) (LA) %, max. 30Resistance to repeated action of sodium sulphate (Na2SO4), 5 cycles, %, max.
6 for split3 for large crushed stone 40-63
Note: (1) - when natural sand is present in the mixture; (2) - when in the mixture it is used only quarry aggregates:
1.5 - when the percentage of the grains which pass through the 0.1 mm sieve is below 8% 2 - when the percentage of the grains which pass through the 0.1 mm sieve is up 8%
Table 5 – CRUSHED STONE OPTIMAL MIXTURE - Grading
Grading limits
LimitPasses in % by mass through sieves with size .... (mm)
0,02 0,2 8 20 31,5 63
0 .... 63 Lower 0 4 30 45 70 90
Upper 3 10 45 70 85 100
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Admissibility conditions regarding the physically shape characteristics, content of decayed grains and impurity content for crushed stone optimal mixture are those indicated in table 3.
The transport of aggregates to the working area shall be done using only accepted stockpiles.
2.3.2.2 Water
The water used to correct the moisture content shall be clear and it shall not contain either organic or inorganic suspensions.
2.3.2.3 Geo-textile Material
The geo-textile material shall be neither woven nor impregnated and it shall be verified according to the Norm C 227 -"Technical norms regarding the use of geo-textiles and geomembranes in construction works".
2.3.2.4 Quality control of aggregates
The minimum frequency of determinations for each type of aggregates is:
one sample each 2000 t for each sort of crushed stone and crushed stone optimal mixture;
one sample each 1000 t for grit;
one sample each 500 t for crushed sand;
one sample each 400 t for ballast;
one sample each 200 t for natural sand.
2.3.3 Construction of the foundation course
2.3.3.1 Establishing the compaction characteristics
A specialised laboratory shall establish the best characteristics of compaction for ballast and either crushed stone or optimal mixture course before starting the works.
By the modified Proctor test, according to STAS 1913/13-83 it shall be established:
du max PM - maximum dry volume weight (g/cm3)
Wopt PM - best moisture content of compaction (%)
The real characteristics for compaction are established in the site laboratory on samples taken from the working area, such as:
du ef - real dry volume weight (g/cm3)
W ef - real moisture content of compaction (%)
du ef
Degree of compaction, gc = ----------------- x 100 du max PM
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2.3.3.2 Trial section
To establish the Method Statement, the equipment and devices necessary to lay and compact, the Contractor shall execute, with the Engineer approval and before starting the works, one trial section for each source of aggregates. The trial section shall be of at least 50m length and at least half of the platform’s width.
The experimentation aims to determine on site, in conditions of current performance, the components of the compaction workshop, its acting procedure for achieving the compaction level, if the thickness provided in the Design can be performed in one or two layers, the adjustment of the spreading devices for obtaining the respective thickness and a right surface.
Compaction on the experimental sections shall be done in the presence of the Engineer, and the control of the compaction degree shall be done by testing it on site or in the laboratory, as the case may be.
In case of the big crushed stone foundation 63-80, the aim is to properly determine the rolling workshop, composed of light and middle compressing rolls, the minimum number of passes of these tubes for their rolling until the fixation of the crushed stone 63-80 and, then, the minimum number of passes after the laying in two successive stages of the filling split 16-25 until the optimal binding is obtained.
In this case, the rolling is considered as finished if the roll wheels do not leave at all tracks on the crushed stone foundation surface, and other stones of the same dimension 63-80 disposed in front of the roll do not enter into the foundation layer, by the contrary, they are broken.
The laboratory on site shall decide the quantity of water that has to be eventually added in order to obtain the best moisture content for compaction. The water shall be added by sprinkling, uniformly distributed in the mixture to ensure the best moisture content level.
The allowed limits regarding the mixture moisture content are more than 1% and less than 2% comparing with the best moisture content level.
In case of large crushed stone (63-80) the compaction is considered completed when the tyre of the roller does not leave marks on the surface of the foundation and stones larger than 40mm, which are thrown in front of the compacting roller, do not penetrate the layer. Moreover, they are crushed without causing any dislocation or deformation to the foundation course.
The preparation and construction of the works as well the measurements performed on the trial section shall be carried out under the Engineer’s supervision and at the Contractor’s expense.
That part from the performed section with the best results will serve as reference section for the rest of the works.
The characteristics obtained on this section shall be recorded down in order to be used for controlling the quality of works in the future.
2.3.3.3 Preliminary conditions
The construction of the crushed stone / optimal mixture foundation shall start only after the lower ballast foundation layer has been verified and accepted by the Engineer.
Aggregates from different stockpiles shall not be laid on the same working area.
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In the working area where the foundation course is not executed over the entire width of the platform, the shoulders shall be completed and compacted at the same time with the construction of the foundation course, so that the shoulders permanently frame the foundation.
To avoid accidentally deterioration, the Contractor shall take all the necessary action to limit the traffic over the compacted and finished course.
The foundation course shall not be laid when:
the moisture content of the ballast is outside the limits, as specified in 3.2;
the ballast is frozen or contains ice;
the weather conditions determine that the roadbed/form layer (if the case) does not meet the requirements for covering.
2.3.3.4 Construction
A. Foundation made of large crushed stone (60-80) over a ballast layer
a. Construction of the lower layer made of ballast
The ballast shall be laid on the formation layer or, if this is not present, on a 7 cm thick insulating sand or geo-textile layer.
Ballast shall be laid and levelled in one single layer so that after compaction the resulted thickness is of 10 cm.
The compaction of the foundation layer shall be done respecting the Method Statement as agreed further to the construction of the trial section.
b. Construction of the upper layer made of large crushed stone 63-80
The crushed stone shall be laid only after the Engineer accepts the lower layer of ballast, previously watered.
After completing the layer rolling, the crushed stone shall be wedged on using split 16-25 and further to this is covered with grit 0-8 or sand.
To protect against accidental deterioration by the time the next layer is constructed, the Contractor shall cover the compacted and finished crushed stone foundation with a protective layer made of grained sand or grit.
B. Crushed stone optimal mixture foundation course
The construction of the insulating layer and the lower ballast foundation course is carried out according to 2.4.A.a.
The crushed stone optimal mixture shall be laid over the ballast layer using a spreader.
The construction of the foundation layer shall be carried out following all the characteristics, as it was decided further to the construction of the trial section.
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2.3.4 Control of construction and acceptance of works
During the construction of the large crushed stone 63-80 or crushed stone optimal mixture courses. The checking and determinations indicated by table 6 shall be performed.
With regard to the bearing capacity of the foundation course, this shall be established after measurements using the lever deflectometer, in compliance with the Technical Instructions CD 31-93.
Table 6 – Determinations for the foundation layer
Determination, verifying procedure or characteristics to verify
Minimum frequency at the working area
STAS
The optimal compaction moisture content (Modified Proctor test)
For each source or when the grading is modified
1913/13-83
Determining the compaction moisture content
- ballast and crushed stone optimal mixture6 points for 2000 m2 1913/1-82
Determining the thickness of the compacted layer
- ballast, large crushed stone and crushed stone optimal mixture
3 points for 2000 m2—
Determining the degree of compaction (measuring the volume weight)
6 points at 2000 m2 1913/15-7512288-85
Verifying the compaction (crushing the stone in front of the roller)
6 points at 2000 m2 6400-84
Determining the bearing capacity at the upper level of the foundation course
in cross-section every 25 m,
on each traffic lane including the emergency lanes
Norm
CD 31-94
2.3.4.1 Verifying the horizontal geometry
The thickness of the foundation course shall be verified wherever necessary but in at least 3 points for 2000 m2 of executed layer. The tolerance is 2 cm.
The width of the course shall be measured wherever necessary but at least in every designed cross-section.
The tolerance, measured from the centre line is +5 cm.
The transverse slope of the foundation is equal to the one of the road pavement, which is indicated in the Design, and it shall be measured wherever necessary, but each 25 m at least. The tolerance is 0.4%.
The levels of the course are measured in the characteristic points of the designed cross-sections.
The maximum deviation of the foundation levels towards the Design shall be 1 cm.
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2.3.4.2 Verifying the compaction and the bearing capacity
Large crushed stone 63-80 foundation courses shall be compacted until the maximum degree of compaction is attained. This is verified by crushing a rock of the same type as the one used for the construction of the layer and with a size of 4cm, which is thrown in front of the compacting roller.
Compaction shall be considered attained if the rock is crushed without causing deformation of the layer.
Foundations made of crushed stone optimal mixture shall be compacted by the time the 100% degree of compaction is attained in at least 95% of the measured points and minimum 98% in all the measuring points.
The degree of compaction shall be determined as dry density by Modified Proctor test complying with STAS 1913/13-83
The bearing capacity of the foundation layer is achieved when the value of the measured elastic deformation does not exceed 250 1/100 mm in any of the measured points.
2.3.4.3 Verifying the characteristics of the surface of the layer
Verifying the irregularities of the foundation surface shall be done using a 3m straight edge, as follows:
In long section, measurements shall be performed wherever considered necessary, but in the axis of each traffic lane at least; the allowed irregularities measured under the 3 m straight edge are 2 cm;
In cross-section, measurements shall be performed wherever considered necessary, but in the designed cross section at least; the allowed irregularities measured under the 3 m straight edge are 1 cm.
2.3.4.4 Acceptance of works on construction stages
After completing the works on a road section and before starting the next layer the Engineer’s approval shall be obtained.
An inspection of the works, which are subject to covering procedure, shall decide whether the works have been carried out according to the Design and the Technical Specifications.
The Acceptance of the works implies the checking of the records during the construction of the works and of the test results as well as the site examination of the works.
After the checking an acceptance report has to be concluded, which authorises the Contractor to proceed to the next construction stage.
2.4 BASE COURSE OF HOT ROLLED ASPHALT MIXTURES
2.4.1 General provisions
These Technical Specifications set out the general technical conditions of execution and verification of the hot rolled asphalt mixture base courses.
The asphalt mixture base course is part of the road structure on which bituminous surfaces are applied.
The application fields of the hot rolled asphalt mixture base course and special technical requirements are
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to be in conformity with the requirements of SR 7970/2001.
The Contractor shall carry out, in an authorized laboratory, all tests and determinations required by this Technical Specification and any other tests requested by the Engineer, including the preparation of mix formula studies for the asphalt mixtures.
In addition to these Technical Specifications, the Contractor must comply with the stipulations of all standards and norms in force.
At least 14 days prior to the beginning of works, the Contractor shall submit for the Engineer’s approval, the Execution Method Statement of the base course, which shall contain, amongst others:
program of works of the base course;
equipment used for materials manufacture and transport;
equipment used for transport, spreading and compaction of the mixture
sources (ballast pits, quarries, producers, suppliers) and aggregates stockpiles, including the proposed haulage route;
study of job mix formula.
To determine the details of the compaction technology, trial sections will be executed to the dimensions and locations to be agreed with the Engineer.
After executing the trial sections, the Execution Method Statement shall be amended with information on the laying and compaction technology:
characteristics of the compaction equipment (weight, width, tire pressure, characteristics of vibrations, speed);
number of passes, with or without vibrations, to accomplish the required degree of compaction;
number of sub-layers of the base course (when the degree of compaction cannot be achieved by laying only one course);
thickness of layer (sub-layers) before and after compaction;
temperature at the beginning and the end of compaction;
revised job mix formula.
The Contractor shall ensure that all applied procedures meet the requirements of this Technical Specification.
The Contractor shall record daily the data referring to the works execution and to the results obtained after measurements, tests and sampling.
Types of mixtures
Based on the aggregates size used for their preparation, the asphalt mixtures for the base course can be:
type AB 1, with medium aggregates: 22 % ... 47% particles over 4 mm;
type AB 2, with large aggregates: 36 % ... 66% particles over 4 mm.
The type of asphalt mixture used for this project is AB2. – SR 7970/2001.
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2.4.2 Materials
2.4.2.1 Natural aggregates
The aggregates used for the preparation of asphalt mixtures for the base course are shown in Table 1.
Table 1 – Contents of aggregates over 4 mm
Road technical class Type of aggregates over 4 mm
I chippings
II chippings (min. 35%) + crushed gravel
III crushed gravel
IV graded gravel
To prepare the asphalt mixture for the base course, the following types of aggregates shall be used:
quarry natural aggregates:
- chippings size 4-8, 8-16, 16-25
- crush sand size 0-4
ballast pit natural aggregates, washed, crushed and sorted:
- natural sand size 0-4;
To approve the sources of aggregates, the Contractor shall run, for each source, all the determinations set out in SR 662 (Table 19) and SR 667 (Table 12).
The aggregates shall be stored separately, in paddocks designed with concrete platforms, with slopes to drain the surface water and separating walls to prevent mixing and contamination.
To approve the batches, the Contractor shall run, for each type of aggregate, all the determinations specified below:
according to SR 667 (Table 8) - a sample from 1000 t every chippings sort;
according to SR 667 (Table 10) - a sample from 500 t for crushed sand;
according to SR 662 (Table 5) - a sample from 200 t for natural sand.
2.4.2.2 Filler
To approve the source, the Contractor shall carry out at monthly intervals all the determinations set out in STAS 539.
Other materials or fine fractions recovered from the asphalt plant exhauster are not to be used as filler replacement.
The filler is stored in covered rooms, away from humidity or in silos with pneumatic loading.
On the stored filler, all the determinations set out in STAS 539 (Table 1) shall be made at the following frequencies:
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1 test per 700 t for limestone filler;
1 test per 100 t for chalkstone filler;
1 test per 50 t for dust slaked lime filler.
2.4.2.3 Bitumen
To prepare the asphalt mixture for the base course in this project, non-paraffin bitumen for roads type D 80/100 shall be used, the works being located at the limit between the warm area and cold area (areas defined in accordance with STAS 174-1/2002).
Various types of bitumen must be separately stored in metallic tanks designed with heating system, temperature recording system (for oil and bitumen), aeration hole, recycling pumps, etc.
To approve the bitumen source, the Contractor shall run at quarterly intervals all the tests set out in SR 754 and Norm AND 537.
At each batch (max. 500 t), all the tests requested by SR 754 shall be made, except for the paraffin contents, density and adherence.
2.4.2.4 Bituminous emulsion
Cationic emulsion with quick break point shall be used to prime the support layer, according to STAS 8877.
To approve the source, the Contractor shall run and re-run for each batch (max. 100 t) all the determinations set out in STAS 8877.
The cationic bituminous emulsion shall be stored in clean metallic tanks, having recycling pumps and heating systems.
2.4.2.5 Additives
The bitumen adherence to the aggregates used to obtain the asphalt mixture must be of min.80%, for roads of technical class I-II (quarry natural aggregates), and of min 75%, for roads of technical class III-IV (ballast pit natural aggregates).
If the bitumen adherence, determined as in STAS 10969/3, is below this value, it is then necessary to improve the bitumen using additives.
The additives shall comply with the following basic conditions:
to be compatible with the type of the utilized bitumen;
to be thermally stable until minimum 200°C;
to ameliorate the bitumen adhesiveness to the natural aggregates without affecting its other characteristics;
not to be toxic, corrosive or inflammable.
The used additives must be approved by the Engineer. For each additive, the Contractor shall present the technical agreement and the quality certificate of conformity.
The determinations and frequencies are those set by the technical agreement of each product.
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2.4.3 Asphalt mixture preparation
2.4.3.1 Establishing the composition
The study to determine the job mix formula and the verification of the materials quality shall be carried out in an authorized laboratory.
The asphalt mixture for the base course shall be fully executed with quarry natural aggregates or of a mix between quarry and ballast pit natural aggregates, as shown in Table 2.
Table 2 – Composition of asphalt mixture (aggregates + filer)
Used natural aggregates
o chippings size 4-8, 8-16, 16-25
o crush sand size 0-4 in ratio of 1:1 with natural sand size 0-4
o filler
The limits of aggregates and filler percentages of the total aggregates quantity are shown in Table 3.
Table 3 – Composition of asphalt mixture (aggregates + filler)
Fractions of aggregates from the total mixture, (% of mass) Composition (%)
Filler and fractions of sands under 0,1 mm 3 …12
Filler and sands, fraction 0,1...4 mm, Difference up to 100%
Aggregates over 4 mm 36…66
Aggregates over 25 mm max. 10
Note: the filler content must be of min. 4% (according to STAS 539).
The grading of the natural aggregates mixture shall be within the limits from Table 4 and figures 1 and 2 (SR 7970/2001).
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Table 4 – Mixture particle size
Sieve dimension Passings (%)
25 mm 90 … 100
16 mm 71 … 100
8 mm 50 … 86
4 mm 34 … 63
1 mm 14 … 39
0,63 mm 10 … 35
0,20 mm 4 … 22
0,1 mm 3 … 11
The bitumen content shall be within the interval 3.4 … 5.0% for crushed aggregates and within the interval 3.3 ... 4.8% for ballast pit aggregates.
The actual bitumen content is established within the formula study, according to STAS 1338/1, STAS 1338/2 and STAS 1338/3.
The deviations admitted from the established dosage shall be within the limits from Table 5.
Table 5 – Limit deviations in mixture composition
Mixture elements Admitted deviations (%)
Bitumen content 0,3
Fractions of natural aggregates: 16 … 25 5
8 … 16 5
4 … 8 5
1 … 4 4
0,20 … 0,63 3
0,1 … 0,2 2
0 … 0,1 1,5
Physical-mechanical characteristics
The physical-mechanical characteristics of the asphalt mixtures shall be determined:
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on Marshall type samples and on cubic specimens made of asphalt mixtures prepared in the laboratory to establish the optimal dosages and of samples taken during works execution, from the mixer or whilst laying;
from the already executed layer.
The physical-mechanical characteristics of the asphalt mixture shall be determined according to STAS 1338/1, STAS 1338/2, SR EN 12697-27, SR EN 12697-28.
The tests results shall be within the limits from Table 6.
Table 6 – Physical-mechanical characteristics of the asphalt mixture for the base course
Characteristics Type of Bitumen Values
Tests on Marshall
Stability (S) at 60oC, (kN) minD80/100 5,5
D80/100 5,0
Flowing value (index), (mm)D80/100 1,5-3,5
D80/100 1,5-4,0
Bulk density, (kg/m3), min D80/100 2200
Water absorption, (% vol) - 2…8
Tests on cubic specimens
Compression resistance at 22oC, (N/mm2), min D80/100 2,5
Reducing of the compression resistance after 28 days of water endurance at 22oC, (%) max.
D80/100 30
Bulk density, (kg/m3), min D80/100 2150
Water absorption, (% vol) D80/100 2…10
2.4.3.2 Asphalt mixing plant
The asphalt mixture shall be prepared in asphalt mixing plants, designed with devices for pre-dosing, drying, resorting of aggregates, devices of dosing the components (aggregates, bitumen, filler), and of forced mixing of the asphalt mixture.
The asphalt mixing plant shall be authorized in accordance with the regulations in force.
The mixing duration shall be sufficient as to accomplish a complete and uniform coating of the natural aggregates and filler with the bitumen.
The asphalt mixing plant shall have devices to avoid the mixture's segregation during storage and loading in the means of transport.
During preparation and laying the asphalt mixture, the temperature shall be within the limits from Table 7.
Table 7 – Temperature regime during manufacturing and laying asphalt mixture
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Execution phase Temperature (oC)D60/80 D80/100
Aggregates at the drier exit 170…190 165... 185Bitumen at the mixer entrance 155…165 150... 160Asphalt mixture at the mixer exit 165…175 160... 170Asphalt mixture during laying min. 155 min. 150Asphalt mixture at the beginning of compaction min. 150 min. 145Asphalt mixture at the end of compaction min. 110 min. 105
The temperatures situated at the high end of the interval are applicable if the works are performed in cold areas or in special circumstances where outside temperatures are below the minimum admitted limit (10 … 150 C)
The asphalt mixture temperature at the mixer exit shall be adjusted within the prescribed interval so that, under the actual transport conditions (distance, means of transport) and the climate conditions, all the laying and compacting temperatures should be ensured as in Table 7.
Heating the aggregates and the bitumen above the values in Table 7 is not permitted.
Heating bitumen for lengthen period or re-heating the same bitumen quantity repeatedly shall be avoided. If, due to technological reasons, the bitumen re-heating could not be avoided, its use is allowed only after the penetration, the softening point and the ductility are checked at 25oC.
2.4.4 Asphalt laying
2.4.4.1 Trial section
To establish the method statement, the equipment and all laying and compacting devices, before the works start, with the Engineer’s approval, the Contractor shall perform a trial section, of at least 150 m length, on the entire width of the way.
During the execution of the trial section, the asphalt mixing plant shall also be verified under working conditions, as well as getting the job mix constant characteristics, established in a laboratory, approved by the Engineer.
Based on the designed thickness of the base course and on the equipment used to accomplish the prescribed grade of compaction, on the trial section it shall be determined whether the mixture is laid in one or more sub-layers. When determining the number of layers there shall be taken into consideration that the thickness of each layer must be within the 6 ... 12 cm.
The preparation, execution of works and the running of tests on the trial section shall be done in the presence of and with the approval of the Engineer.
The preparation, execution of works and the measurements taken on the trial section shall be done at the Contractor’s expense.
Changing the job mix formula will require the execution of a new trial section.
The results obtained from the trial section shall be used to finalize the procedure of execution, and the reference document relating to layer execution.
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2.4.4.2 Preparation of support layer
The execution of the base course shall not begin before the support layer is verified and approved by the Engineer.
Before laying the asphalt mixture, the support layer shall be cleaned and primed with bituminous emulsion. The priming of the support layer is to be applied by mechanized spraying equipment, ensuring the evenness and the prescribed rate of spread.
Based on the support layer nature, the quantity of the emulsion spread for priming shall ensure a rate of spread of (0,3...0,5) kg residual bitumen per square meter, spread as continuous thin layer.
2.4.4.3 Transport
The asphalt mixture shall be transported in tipping lorries, with clean and dry tipper bodies, equipped with a tarpaulin covering the entire load to prevent temperature losses.
2.4.4.4 Execution
Laying the asphalt mixtures for the base course shall be carried out only when the ambient temperature is over 100 C, during dry weather. Works interrupted during strong winds or rains shall only be resumed after the support layer is dry.
Laying the asphalt mixtures on the prepared support layer shall be with spreaders – finishers, equipped with a sensor and automatic leveling system, to ensure the mixture pre-compaction.
The asphalt mixture shall be laid uniformly and continuously on each layer. If accidental interruptions occur, the procedure according to SR 174-2 must be followed.
The compaction shall be achieved with tyre compactors and/or with smooth wheeled rollers rolls, equipped with vibrating devices.
The places inaccessible to compactors (along the kerbs, around the gullies or manholes) shall be compacted with adequate means approved by the Engineer.
When beginning the works to the adjacent lane, or when continuing the work at the same lane, in the working joints area, the asphalt shall be cut on the whole thickness of the layer so that a vertical sharp margin result, which shall be primed as in SR 174-2.
When executing the works on successive layers, the transversal and longitudinal working joints of the successive layers shall be overlapped by at least 10 cm, the upper layer being applied within 24 h of first layer being laid. If the second layer cannot be executed within 24 h, the surface of the executed layer shall be prepared by cleaning and priming.
The bituminous surface laid (binder course) shall be applied immediately after the execution of the base course.
2.4.5 Control of execution and acceptance of works
The quality control of execution of the asphalt mixture base course implies:
control of materials quality;
control of preparation and laying the mixture;
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control of executed layer quality.
2.4.5.1 Quality control of materials
During works execution, all verifications and determinations shall be executed in the site laboratory, on each supplied batch.
2.4.5.2 Control of preparation and laying the mixture
Control of the asphalt mixture plant
During preparation and laying, the following shall be checked:
functioning of pre-dosing devices: daily;
functioning of dosing devices: at the beginning of each shift;
bitumen temperature when put in the mixer: permanently;
aggregates temperature at the exit of the drier: permanently;
asphalt mixture temperature at the exit of the mixer: permanently.
Control of mixture composition and quality
Observing the pre-established asphalt mixture composition, through tests run in site laboratory:
- grading analysis of the mixture between aggregates and filler at the mixer exit, before adding the bitumen: daily or anytime necessary;
- asphalt mixture composition through extractions, on mixture samples taken from the mixer and whilst laying: daily (1/400 tons of mixture)
The quality of asphalt mixture, through tests run in an authorized laboratory, on asphalt mixture samples: 1 test at 400 tone manufactured mixture, but at least once a day;
- lB softening point, of the bitumen extracted from the asphalt mixture;
- the physical-mechanical characteristics on Marshall tests and cubic specimens.
Characteristics of bitumen from the asphalt mixture
The bitumen from the asphalt mixture taken during execution, from the mixer or whilst laying, shall have an IB softening point higher with max 90C than the value measured before manufacturing the mixture.
The lB softening point is determined in accordance with STAS 60/69, and the bitumen extraction and recovery from the mixture is done in accordance with STAS 1338-2, with SoxhIet device, with the centrifugal (or in accordance with the new regulations: SR EN 12697-1, SR EN 12697-3 and SR EN 12697-4).
If organic solvents containing chlorine are used during extraction (e.g. Chloroform), solvents which hardens the bitumen, the real value of the IB softening point shall be obtained by subtracting 80C from the measured IB value.
The focus is on the complete removal of the filler from the bitumen solution at extraction, by centrifuging
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or by decantation for min. 24 hours (in the case of using Soxhlet extractors or centrifugals which do not have filler separation system).
2.4.5.3 Quality control of the executed layer
Verification of geometrical elements
The slope in cross-section and the slope in longitudinal profile of the asphalt mixture base course are the same as in the bituminous pavement case.
Table 9 – Tolerances of the bituminous pavement layer
Measured element Tolerance
Layer’s thickness ±10%Layer’s width ±5 cmCross-section slope ±0.4%Levels of the cross-section and longitudinal profile ±1 cm (observing the distance between
the vertical alignment vertexes)Evenness of surface (measured using the 3m straight edge)
0.3 cm
Verification of asphalt mixture quality and compaction level
The verification of the executed layer shall be done on cores taken from the layer (at least 1 sample at 7000 m2) performing the following measurements and tests:
Thickness of the laid layer;
Bulk density;
Water absorption;
Compaction level;
Mixture characteristics (composition, physical-mechanical characteristics, IB softening point of the extracted bitumen).
The cores shall be extracted in the presence of and from the locations as directed by the Engineer.
The grade of compaction shall be measured as a percentage ratio between the bulk density of the mixture compacted into the layer and the bulk density determined on Marshall tests prepared in laboratory from the same asphalt mixture.
The bulk density of the layer mixture shall be determined on cores taken from the already executed layer or through non-destructive measurements (e.g. with gamma density meter).
The tests results must be within the limits from Table 10.
Table 10 – Mixture characteristics to determine the compaction
Characteristics Admitted values
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Bulk density, (kg/m3), min 2150
Water absorption, (%vol) 2 … 10
Compaction level, (%), min 96
2.4.5.4 Acceptance of works
After finishing the works on one section, the performed works shall be presented to the Engineer for approval, before laying the next course.
The inspection of the works to be covered must establish whether they were performed in compliance with the design and this Specification.
The Engineer shall verify the records during execution and the tests results, as well as the actual examination of works.
After the verification is done, the record of acceptance shall be prepared in order to authorize the next phase of execution.
2.5 BITUMINOUS SURFACES
2.5.1 General provisions
These Technical Specifications set out the general technical conditions of execution and verification of the bituminous surfaces.
The Contractor shall perform, in an authorized laboratory, all tests and determinations required by these Technical Specifications and any other tests and determinations requested by the Engineer.
In addition to these Technical Specifications, the Contractor must comply with the stipulations of all standards and norms in force.
Fourteen (14) days prior to the beginning of works, the Contractor shall submit for the Engineer’s approval, the Working Technology for the bituminous surface, which shall contain, amongst others:
program of works for the bituminous surfaces;
equipment used for materials manufacture and transport;
equipment used for transport, spreading and compaction of the mixture
sources (ballast pits, quarries, producers, suppliers) and aggregates storage, including the access paths to each of them.
To determine the details of the laying and compaction technology, trial sections will be executed, whose dimensions and locations shall be established together with the Engineer.
After executing of the trial sections, the Working Technology shall be completed with information on the compaction technology:
characteristics of the compaction equipment (weight, width, tire pressure, vibration characteristics, speed)
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number of passes, with or without vibrations, to accomplish the grade of compaction as to comply with these Technical Specifications;
temperature for starting and finishing the compaction;
job mix formula (optimal dosages).
The Contractor shall make sure that, by applying all the procedures, he meets the requirements of these Technical Specifications.
The Contractor shall daily record the data referring to the works execution and to the results obtained after measurements, tests and determinations.
Types of mixtures
The bituminous surfaces are of the hot rolled asphalt concrete type. – SR 174/1-2002.
They are composed of 2 layers:
wearing course – in accordance with Annex C;
binder layer – in accordance with Annex D.
The references related to all the types of asphalt mixtures used for hot rolled bituminous surfaces are shown in Annex E.
2.5.2 Materials
2.5.2.1 Natural aggregates
Depending on the source, the natural aggregates are classified into:
quarry natural aggregates (in accordance with SR 667);
chippings, size 4-8, 8-16 and 16-25;
crushed sand, size 0-4;
gravel pit natural aggregates, processed by washing and grading or by washing, crushing and grading (in accordance with SR 662);
natural sand, size 0-4.
Minimal class of the rock
The minimal class for the rock from which natural aggregates for bituminous surfaces are obtained, shall be established in accordance with SR 667 (Table 3).
The physical-mechanical characteristics of the rock resulted from the quarry aggregates shall be in accordance with SR 667 (Table 2).
Storage
Each type and size of natural aggregates shall be separately stored, in bins provided with concrete platforms, having water draining slopes and separating walls in order to avoid aggregates mixing.
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2.5.2.2 Filler
The filler to be used shall be lime or chalkstone, in accordance with STAS 539. For the asphalt mixtures stabilized with fibres, the filler shall comply additionally with the condition that not more than 20% of particles are less than 0.02 mm. Other materials as a replacement for filler or the fine fractions recovered from the asphalt plant exhauster shall not be used.
The filler shall be stored in bunkers with pneumatic charging. The Agglomerated filler shall not be used.
2.5.2.3 Bitumen
For all types of asphalt mixtures, bitumen type D80/100 shall be used, excepting MASF 16 for which bitumen type D60/80 shall be used.
In order to approve the bitumen source, the Contractor shall perform and re-execute quarterly all the tests stipulated in SR 754 and NAR Norm 537.
For each batch (max. 500 t), all the tests provided in SR 754 shall be performed, except the paraffin content and the density tests.
Bitumen shall comply with the requirements specified in Table 1. For this project, bitumen type D60/80 shall be used.
Table 1 – Characteristics of bitumen
Characteristics Admissible values STASPenetration at 25C, (1/10 mm) 60-80 80-100 42-68Softening point IB, (C) 48-55 44-49 60-69Ductility at 25C, (cm), min. 100 100 SR 61-96Ductility at 5C, (cm), min. 4.0 5,0 SR 61-96Breaking point Fraass, (C), max. -13 -15 113-74Inflamability point Marcusson, (C), min. 250 250 5489-80Solubility in organic solvents, (%), min. 99 99 115-80Stability in warm conditions in thin layer at 163C
8099-74Method II
- mass loss, (%), max. 0,80 0,80- residual penetration at 25C, (%), min. 50 47- increase of the softening point, (C), max. 9 9- residual ductility at 25C, (cm), min. 50 75Paraffin content, (%), max. 2.0 2.0 8098-68Density at 15C, (g/cm3), min. 0,995 0,992 35-81Adhesiveness on standard aggregate, (%), min.
80 80 10969/3 - 83
Adhesiveness on the used aggregate 80 80 10969/3-83Colloidal instability index, (), max. 0.5 0.5
Bitumen with additives
When the adhesiveness of the bitumen to the natural aggregates utilized, determined in accordance with STAS 10969/3, is smaller than 80%, the bitumen shall be improved.
The additives shall comply with the following compulsory conditions:
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to be compatible with the type of the utilized bitumen;
to be thermal stable until minimum 2000C;
to ameliorate the bitumen adhesiveness to the natural aggregates without affecting its other characteristics;
not to be toxic, corrosive or inflammable.
The additives which are intended to be used shall be subject to the Engineer’s approval. For each additive presented for approval, the Contractor shall submit also the technical agreement and the quality certificate of conformity.
The bitumen with additive shall be in compliance with the requirements of table 1, excepting the adhesiveness, which will be determined for the natural aggregates utilized.
The storage period of the bitumen plus additive shall be maximum 3 days, and the temperature during storage will be within the interval 120-1400C.
The determinations and the frequencies shall be those specified in the technical agreement for each product.
2.5.2.4 Bituminous emulsion
For the priming of the support layer, rapid setting cationic bituminous emulsion shall be used, complying with the requirements of STAS 8877.
The source from which the Contractor intends to supply the emulsion, shall be submitted to the Engineer’s approval.
The bituminous emulsion shall be stored in vertical metallic tanks, which shall be clean and provided with re-circulation pumps and heating system.
2.5.2.5 Fibres
The fibres used for preparing the asphalt mixtures stabilized with fibres, for the execution of the bituminous surfaces, shall be cellulose fibres or grains, either bitumen or not.
The type and the fibres dosage in the asphalt mixture will be established based on the preliminary study performed by an authorized laboratory.
The fibres type which is intended to be used shall be submitted to the Engineer for approval.
For each type of the fibres for which the Contractor requests the Engineer’s approval, the Contractor shall provide also the technical agreement and the quality certificate of conformity.
2.5.3 Establishing the job mix composition
Asphalt mixtures for bituminous surfaces shall be entirely executed of quarry aggregates or mixture of quarry and ballast pit natural aggregates.
Table 2 – Natural aggregates for bituminous surfaces
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Asphalt mixture type Natural aggregates used
Asphalt mixtures stabilized with fibres
- chippings : size 4-8 and 8-16- crushed sand: size 0-4 - filler
Rough asphalt concrete - chippings : size 4-8 and 8-16- crushed sand: size 0-4- filler
Asphalt concrete rich in chippings
- chippings : size 4-8, 8-16 and 16-25- crushed sand size 0-4- natural sand size 0-4 - filler
Asphalt concrete with crushed gravel
- crushed gravel size 4-8, 8-16, 16-25- natural sand size 0-4- filler
Rough asphalt concrete with chippings
- chippings: size 4-8, 8-16 and 16-25- crushed sand: size 0-4- natural sand size 0-4 - filler
Open graded asphalt with crushed gravel
- crushed gravel size 4-8, 8-16, 16-25- crushed sand size 0-4 - natural sand size 0-4- filler
Open graded asphalt with sizeed gravel
- gravel size 4-8, 8-16, 16-25- crushed sand size 0-4 - natural sand size 0-4- filler
The dosage limits for the natural aggregates and filler, for each type of asphalt mixture shall be those specified in Table 3.
The grading area of the natural aggregates mixture for each type of asphalt mixture shall be within the limits presented in table 4 and figures 1-8 from the annex. For the open graded asphalt concrete for the binder course, crushed sand or mixture of crushed sand with natural sand shall be used, natural sand being maximum 50%.
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TABLE 3
No. Fractions and natural aggregates from the
total mixture
Wearing course Binder course
Type of the asphalt mixture
BA8
BA8a
BA16
BA16m
BA16a
BA25
BA25a
BAR16
BAR16m
BAR16a
MASF8 MASF16 BAPC16
BAD25
BAD25m
BAD25a
BADPC25
BADPC25a
BADPS25
BADPS25a
1 Filler and sand fractions under 0,1 mm (%) 9-13 9-13 6-13 9-11 11-14 10-14 9-13 2-7 2-7 2-7
2 Filler and sand fraction (0,1 – 4) mm (%) Difference up to 100 %
3 Chippings with size over 4 mm (%) 22-45 34-58 39-60 47-61 45-60 63-75 - 55-72 - -
4 Crushed gravel with size over 8 mm (%) - - - - - - 18-34 - 39-58 -
5 Graded gravel with size over 8 mm (%) - - - - - - - - - 39-58
Note : The filer content for the open graded asphalt concrete is minimum 2 %
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TABLE 4
Size of the mesh according to SREN 933-
2
Type of the asphalt mixture
BA8
BA8a
BA16
BA16m
BA16a
BA25
BA25a
BAR16
BAR16m
BAR16a
MASF8 MASF16 BAPC16BAD25,BAD25m , BAD25a,
BADPC25 , BADPC25a, BADPS25 ,BADPS25a
Passings through the sieve with square meshes – SREN 933-2 (%)
25 mm - - 90-100 - - - - 90-100
16 mm - - 72-90 90-100 - 90-100 95-100 73-90
8 mm 90-100 66-85 54-80 61-74 95-100 44-59 66-82 42-61
4 mm 56-78 42-66 40-61 39-53 40-55 25-37 42-66 28-45
2 mm 30-55 30-55 30-50 30-42 19-28 20-25 30-55 20-35
1 mm 22-42 22-42 20-40 21-31 16-22 16-22 21-42 14-32
0.63 mm 18-35 18-35 15-35 18-25 13-20 13-20 18-35 10-30
0,20 mm 11-25 11-25 8-25 11-15 12-16 11-15 11-25 5-20
0,10 mm 9-13 9-13 6-13 9-11 11-14 10-14 9-13 2-7
Grading area for the natural aggregates mixture Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8
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2.5.3.1 Cellulose fibres content in the asphalt mixtures
The cellulose fibres content in the asphalt mixtures with fibres MASF8 and MASF16, shall be within the limits (0.5 – 1.0%) from the asphalt mixture weight, so that an equilibrium to be established between the inferior limit of the bitumen dosage, the fine fraction dosage and cellulose fibre dosage.
The optimal content of bitumen, of fine fraction and of cellulose fibre shall be established through the preliminary study elaborated in accordance with STAS 1338/ 1, 2 and 3, by a certified laboratory.
The recommended limits for the execution of the preliminary laboratory studies, in order to establish the optimal content of bitumen, are presented in table 5.
Table 5 Binder content for different types of asphalt mixtures
Type of the layerType for the asphalt
mixture
Binder content from the mass of the asphalt
mixtures (%)
Technical class of the road
Wearing course
MASF8MASF16
6,7-7,5 I-V6,5-7,5 I-V
BAR16m, BAR16a 5,7-6,2 I-III5,7-6,2 II-III
BA16m6,0-7,0 I-II6,3-7,3 III
BA16, BA16a6,0-7,0 II6,3-7,3 III6,5-7,5 IV-V
BA8, BA8a 6,5-7,5 IV-VBA25, BA25a 5,5-7,0 IV-V
BAPC16, BAPC16a 6,0-7,5 IV-V
Binder course
BAD25m 4,0-5,0 I-IIIBAD25, BAD25a 4,0-5,0 I-V
BAPC25, BAPC25a 4,0-5,0 III-VBADPS25, BADPS25a 4,0-5,0 IV-V
2.5.3.2 Filler/bitumen ratio
The filler/bitumen ratio recommended for the asphalt mixtures types included in the present Technical Specifications is in accordance with Table 6.
Table 6 – The recommended filler/bitumen ratio
Type of the layer
Type of the asphalt mixture Filler: binder ratio
(recommended)
Wearing course
Rough asphalt concrete 1,6-1,8Asphalt concrete rich in chippings
- with maximum size of the grain 16 mm- with maximum size of the grain 25 mm
1,3-1,81,1-1,8
Asphalt concrete with crushed gravel 1,6-1,8Binder course Open graded asphalt concrete 0,5-1,4
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2.5.4 Physical – mechanical characteristics
The physical-mechanical characteristics for the asphalt mixtures shall be determined on cylinder samples made of asphalt mixtures prepared in laboratory in order to establish the optimal dosages, but also during the works execution, samples are to be taken from the mixer or whilst laying, or from the finished layer, in order to check the quality of the asphalt mixtures.
The sampling during the works and from the finished layer shall be performed in accordance with SR EN 12697-27.
The physical–mechanical characteristics for the asphalt mixtures, prepared with non-paraffin bitumen for roads or bitumen with additives, shall be in the limits specified in Tables 7 and 8.
Table 7 – The asphalt mixtures characteristics for bituminous surfaces
Type of the asphalt mixture
Type of the bitumen
Technical class of the road
Characteristics on cylindrical laboratory samples type Marshall
Stability (S) at 60 ºC
(KN) min
Flow Index (I) (mm)
Ratio S/ Ι (ΚΝ / mm)
Bulk density (Kg / mc)
minim
Water Absorption (%) volume
BA8, BA25
BA8a
BA25a
D 80/100
D 80/100aIV-V 5.5 1.5-4.5 1.2-3.6 2300 2-5
BA16
BA16a
D 80/100
D 80/100a
II 8,0 1,5-4,0 2,0-5,3
2300 2-5III 7,0 1,5-4,0 1,7-4,6
IV-V 6,0 1,5-4,5 1,3-4,0
BAR16
BAR16a
D 80/100
D 80/100a
I-II 8,5 1.5-4,0 2,1-5,62300 3-5
III 7,5 1,5-4,0 1,8-5,0
BAPC16
BAPC16a
D 80/100
D 80/100aIV-V 5,5 1,5-4,5 1,2-3,6 2300 2-5
BAD25
BAD25a
D 80/100
D 80/100aI-V 4,5 1,5-4,5 1,0-3,0 2250 2-5
BADPC25
BADPC25a
D 80/100
D 80/100aIII-V 4,0 1,5-4,5 0,9-2,6 2250 2-5
BADPS25
BADPS25a
D 80/100
D 80/100aIV-V 4,0 1,5-4,5 0,9-2,6 2250 2-5
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Table 8 – Characteristics of the asphalt mixture for the bituminous surfaces
Characteristics
Type of the asphalt mixtureBAR16, BAR16a,
BA16, BA16A, BA8, BA8a, BA25, BA25a
BAD25, BAD25a, BADPC25, BADPC25a, BADPS25, BADPS25a
Characteristics on the cylinders executed at the gyratory compaction press:- Voids volume for 80 rotations, % max.- Voids volume for 120 rotations % max.
5,0-
-9,5
Resistance to permanent deformations- dynamic flow at 40ºC and 1800 pulsations 10-4
mm max.7600 -
Elasticity modulus at 15 ºC MPa min.:- warm climatic area- cold climatic area
42003600
36003000
Tiredness resistance :- number of cycles until cracking at 15ºC min.
-- 4x105
2.5.4.1 Physical-mechanical characteristics of the asphalt mixtures stabilized with fibres
The physical-mechanical characteristics of the asphalt mixtures stabilized with fibres shall be between the limits specified in table 9.
Table 9 – Characteristics of the asphalt mixtures stabilized with fibre
CharacteristicsType of the asphalt mixtureMASF8 MASF16
Schellenberg Test, % max. 0,2 0,2Characteristics on cylindrical laboratory samples: - stability (S) at 60ºC KN, min.- flow index (I) at 60ºC mm- bulk density kg / m3 , mm- voids volume %
7,01,5-3,523003-4
7,01,5-3,523003-4
Resistance to permanent deformations- dynamic flow at 40ºC and 1800 pulsations 10-4 mm max. 10000 10000
- deformation speed at the wheel track test (VDOP), mm /hTemperature (2)
45ºC 60ºC 45ºC 60ºC The average number of vehicles (1)< 1500 6,0 8,0 6.0 8.0
1500-3000 4,0 6,0 4,0 6,03000-6000 2,0 3,5 2,0 3,5>6000 <2,0 <3,5 <2,0 <3,5
Depth of the ruts , mmThe average number of vehicles (1) < 1500 6,0 9,0 6,0 9,0
1500-3000 5,0 8,0 5,0 8,03000-6000 4,0 7,0 4,0 7,0>6000 <4,0 <7,0 <4,0 <7,0
Elasticity modulus at 15 ºC Mpa, min. 3600 4000Permanent deformation to tiredness (3600 impulses)at15ºC, 10 –4 max.
1200 1000
Note : 1) commercial vehicles or buses in 24 hours used for the long-term traffic 2) 45ºC – cold climatic area; 60ºC – warm climatic area;
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2.5.4.2 Determination of the physical-mechanical characteristics
Determination of the physical-mechanical characteristics on cylindrical laboratory samples type Marshall of the asphalt mixtures with bitumen and bitumen with additives, shall be performed in accordance with STAS 1338 / 1 and STAS 1338 / 2.
For the asphalt mixtures stabilized with fibres, the cylindrical laboratory samples shall be made depending on the traffic intensity, at the temperature of 135+ 5ºC, in accordance with the regulations in force, and the determinations on cylindrical laboratory samples type Marshall shall be performed in accordance with STAS 1338 / 2.
The characteristics mentioned in the tables 7, 8 and 9 shall be determined in accordance with the technical regulations in force.
The Schellenberg test shall be executed in accordance with Annex B.
The characteristics of the bitumen extracted from the asphalt mixture
The bitumen contained in the asphalt mixture taken from the mixer and during the works execution shall contain a softening point „ring and ball” having maximum 9ºC above the bitumen initially used for the preparation of the asphalt mixture. Exception from this: checking the bitumen extracted from the MASF asphalt mixtures.
The asphalt mixture shall be taken for tests in accordance with SR EN 12697-27, and the preparation of the asphalt mixtures on order to extract the bitumen shall be made in accordance with SR EN 12697-28.
2.5.4.3 Characteristics of the bituminous surface layers
The compaction degree
The compaction degree shall be determined through laboratory tests on cores or determinations in-situ in accordance with SR 174 / 2 and it represents the ratio between the bulk density of the asphalt mixture compacted in layer and the bulk density determined on Marshall laboratory samples executed in the laboratory from the respective asphalt mixture.
The bulk density of the asphalt mixture in layers shall be determined on cores taken from the already executed layer or through determinations in-situ with the gamma-densimeter .
The laboratory tests performed to check the compaction degree comprise the determination of the bulk density and water absorption on plates (100 x 100 ) mm or on cylindrical cores having the diameter of (100-200) mm undisturbed.
The technical conditions for the bulk density, the water absorption and the compaction degree of the asphalt mixture shall be in accordance with table 10.
Table 10 – Characteristics of the asphalt mixtures for bituminous surfaces
Type of the asphalt mixtureBulk density kg / m3,
min
Water absorption %
volume
Compaction degree % min.
Asphalt mixture stabilized with fibres MASF8, MASF16
2300 2-6 97
Rough asphalt concrete BAR16m 23004-7 96BAR 16a
BAR162250
98
Type of the asphalt mixtureBulk density kg / m3,
min
Water absorption %
volume
Compaction degree % min.
Asphalt concrete rich in chippings BA16m
2300
2-6 96BA8a, BA16a, BA25a,BAPC16a,BA8, BA16, BA25, BAPC16
2250
Open graded asphalt BAD25m 2250
3-8 96BAD25a, BADPC25a, BADPS25a, BAD25, BADPC25, BADPS25
2200
Resistance to permanent deformations
The resistance to permanent deformation shall be determined on cores taken from the executed layer, respectively from the wearing course.
The admissible values, depending on the traffic, are presented in the Table 9.
2.5.4.4 Characteristics for the surface of the executed layer
The characteristics for the surface and the technical conditions have to be in accordance with Table 11.
Table 11 – Characteristics for the surface of the executed layer
No. Characteristics Admissibility conditions Testing method
1
Evenness in longitudinal section1)
Evenness index, IRI, m / km
CD 155/2001 and AND 563/2000
- roads of technical class I-II < 2.5- roads of technical class III < 3.5- roads of technical class IV < 4.5- roads of technical class V < 5.5
2
Uniformity in longitudinal profile 1)
Admissible roughness measured under the screed of 3 m , mm
SR 174 / 2- roads of technical class I and streets of technical category I-III
< 3.0
- roads of technical class II and streets of technical category IV
< 4.0
- roads of technical class III- V < 5.03 Roughness 2)
Roughness with SRT pendulum, units SRTSTAS 8849- roads of technical class I-II > 80
- roads of technical class III > 70- roads of technical class IV-V > 60Geometrical roughness, HS, mm STAS 8849- roads of technical class I-II > 0.7- roads of technical class III > 0.6- roads of technical class IV-V > 0.55
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No. Characteristics Admissibility conditions Testing method
Coefficient of friction ( m GT)- roads of technical class I – II- roads of technical class III - IV
≥0.95≥0.7
Technical regulations in force with the
measuring apparatus Grip Tester
4Homogenity. Surface appearance
Aspect without degradations as bitumen
in excess, fissures, porous areas, open graded, polished
visually
Note :
1) The eveness in longitudinal profile will be determined by measuring the eveness index IRI, or the roughnesses under the screed of 3 m;
2) The roughness will be determined with the SRT pendulum measures, or by measuring the geometrical roughness HS.
The determination of the surface characteristics for the bituminous pavements shall be performed in a month since their execution.
Rules and methods for verification the characteristics of the asphalt mixtures
The verification of the asphalt mixtures characteristics, provided in Tables 7, 8, 9, 10, 11 and 12 shall be done in the following steps:
elaboration of the preliminary study for establishing the composition of the asphalt mixture;
verification of the asphalt mixture characteristics on samples taken during the works execution;
verification of the characteristics for the executed bituminous layer.
The types of determinations, depending on the type of the asphalt mixture and the technical class of the road, together with their frequency, are shown in Table 12.
Table 12 – Types of determinations
Nature of the control or test and the frequency
CharacteristicsType of the asphalt
mixturePreliminary study for the
determination of the asphalt mixture composition
Physical-mechanical characteristics on laboratory samples Marshall
All the types of asphalt mixtures for wearing and binder course (table 1 and 2) without taking into consideration the technical class of the road or the technical category of the street
Characteristics :- The determined voids volume (with the gyratory compaction press)- Resistance to permanent deformations - Elasticity modulus - Resistance to tiredness
MASF8, MASF16, without taking into consideration the technical class of the road or the technical category of the street
100
Nature of the control or test and the frequency
CharacteristicsType of the asphalt
mixtureThe asphalt mixtures destined to the wearing course for the technical class of the road I, II and the technical category of the street I, II
Verification of the asphalt mixtures characteristics taken during the execution - frequency: 1/400 tonnes of asphalt mixture
Physical-mechanical characteristics on laboratory samples Marshall
All types of asphalt mixtures for the wearing and binder course (Table 1 and 2)
Quality verification of the bituminous layer executed on cores: -frequency : 1 core / 7000 m2
Characteristics :- bulk density;- water absorption;- compaction degree.
All types of asphalt mixtures for the wearing and binder course in accordance with the Table 10
Resistance at permanent deformations MASF8, MASF16The asphalt mixtures destined for the wearing course for the technical class of the road I, II and the technical category of the streets I, II ( Table 1)
2.5.5 Preparation and laying of the asphalt mixtures
2.5.5.1 Preparation of the asphalt mixtures
The composition of the asphalt mixtures that are to be used to execute the bituminous surfaces shall be established by the Contractor based on a preliminary study taking into account the fulfilment of the technical conditions specified in the present Technical Specifications.
The preliminary study regarding the composition of the asphalt mixture has to be made in an authorised laboratory.
The mix formula for each type of the asphalt mixture, together with all studies and tests results obtained in the laboratory, inclusively all the related documents, shall be presented to the Engineer for his approval.
The report regarding the composition of the asphalt mixture submitted for approval shall include at least the following documents:
the entire analysis of the materials used in the testing procedure (natural aggregates, bitumen, filler, polymeric, additives, fibres etc.)
the Marshall test for 5 binder dosages distributed on one side and the other side of the retained bitumen dosage.
The Marshall laboratory samples will be compacted in laboratory by applying 75 beats each side. The parameters that have to be determined on the Marshall laboratory samples are those provided in the Tables 7, 8 and 9.
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The Conformity Certificates for the Materials Quality (natural aggregates, bitumen, filler, fibres, polymeric, additives etc.)
All the dosages for natural aggregates and filler shall be established depending on the total weight of the dry granulated material, including the fine parts, and the binder dosage shall be established depending on the weight of the asphalt mixture.
The grading of the natural aggregates for each type of the asphalt mixture shall be situated between the limits indicated in the Tables 4 and 5 and in the Figures 1, 2, 3, 4, 5, 6, 7 and 8.
The proposed mix formula shall applied on the trial section.
2.5.5.2 Installation for preparing the asphalt mixture
The asphalt mixtures shall be prepared in authorised plants, operated by authorized personnel.
The asphalt plant will shall be commissioned and present the technical characteristics that will allow the obtaining of the performances requested by different types of asphalt mixtures specified in the Technical Specifications.
The asphalt plant shall be automatic and have devices for the pre-dosage, drying, re-sizing, gravimetric and volumetric dosage of the aggregates with the bituminous binder, including the additive dozer for bitumen.
Re-grading is compulsory for the installations with non-continuous flow.
For the installations with continuous flow, humidity correction, meaning the correlation between the natural aggregate quantity and the bitumen quantity put into the dryer-mixer, shall be made automatically.
Independently of the installation type, recording and displaying systems shall be provided for the bitumen temperature, the natural aggregates and the asphalt mixture and to assure the precision of the dosage.
For the volumetric dosage of the bitumen, account shall be taken of the fact that its density varies with the temperature so that for 150 C – 180 C, 1 kg of road bitumen has a volume of (1,09-1,11) litres.
Storing and the warming of the bitumen
The asphalt plant shall have tanks for storing a bitumen quantity more or at least equal with the daily consumption average.
The tanks shall be provided with a level indicator and a heating system for the binder until the necessary temperature is reached, avoiding its over-heating.
Heating the natural aggregates and the bitumen over 190C is not to allowed, to avoid the modification of the binder characteristics in the technological process.
Storing of the filler
At the plant where the asphalt mixture is prepared, the filler shall be stored in bunkers provided with devices for an appropriate supplying and extraction (pneumatic).
Filler containing lumps shall not be used.
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Storing, drying and re-grading of the natural aggregates
The storing conditions of the natural aggregates of different types are those provided at Chapter 1. Materials point 1.1.
The installation for preparing the asphalt mixtures shall be provided with the necessary mechanical equipment in order to uniformly supply the natural aggregates for assuring a constant production.
The natural aggregates shall be gravimetrically treated, and the dosage devices shall maintain the supplying of the aggregates in accordance with the mix formula already approved by the Engineer regarding the composition of the asphalt mixture with the admissible deviations of the grading on fractions specified in Table 13.
Table 13 – Maximum deviations allowed for the dosage of the aggregates
Mixture components Admissible deviations in comparison with the
dosage %
Aggregates 16 – 25 + 5
8 – 16 + 5
4 – 8 + 5
2 – 4 + 4
1 – 2 + 4
0,63 – 1 + 3
0,2 - 0,63 + 3
0,1- 0,2 + 2
< 0,1+ 1.5
+ 1,0 – pt. MASF
Bitumen +0,3
Technological flow for preparing the asphalt mixture
Setting the installations pre-dozers by testing so that the mixture grading of the natural aggregates to comply with the prescriptions, within the tolerance limits specified in Table 13.
Insertion of the natural aggregates into the dryer or (dryer-mixer) where their drying and the heating take place;
re-sizing the natural aggregates and the gravimetric dosage by sizes (for the installations in non-continuous flow)
insertion of the warm natural aggregates into the mixer where they mix with the cold filler, separately dosed;
the dosage of the warm bitumen and its introduction into the mixer or the dryer-mixer;
mixing the components of the asphalt mixture and its evacuation into the storage bunkers;
the mixing period, depending on the installation type, has to be sufficient to perform a complete and uniform coating of the natural aggregates and of the filler with bituminous binder;
for the asphalt mixture stabilized with fibres, the mixing period of the natural aggregates with the fibre has to be of 25-30 seconds (for assuring the dispersion of the fibre in the
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mineral mixture and thus its homogeneity in the asphalt mixture), and after the introduction of the bituminous binder, the mixing will go on another 40-50 seconds. The total period for mixing will be comprised between 65-80 seconds.
The thermal regime applied for the preparation of the asphalt mixture, depending on the bitumen, shall be within the limits specified in Table 14.
Table 14 – Thermal regime for the preparation of the asphalt mixture
Materials and the execution phase Temperature C depending on the type of bitumenD 60 / 80 D 80 / 100
- natural aggregates at the exit from the dryer 170-190 165-185-bitumen at the entrance into dryer 155-165 150-160- Asphalt mixture * at the exit from the dryer 165-175 160-170 * when laying min 155 min 150
* at the beginning of the compaction min. 150 min. 145 * at the end of compaction min. 110 min. 105
The temperatures from the upper level of the interval shall be applied when executing works in cold climatic areas or when the atmosphere temperatures are situated at the minimum level of + 10 C and +15C for the asphalt mixtures stabilized with fibres.
The storage and the loading of the asphalt mixtures
At the exit from the mixer special devices shall be provided to avoid the segregation of the asphalt mixture during storage and/or loading it in the transportation means.
Control of the fabrication
The quality control of the asphalt mixture shall be done by preliminary tests and during execution, with the frequency from Table 12.
2.5.5.3 Laying the asphalt mixture
The trial section
The Contractor shall perform a trial section of at least 200 m length, on the entire width of the way in order to establish the method statement, the equipment and the devices for laying and compaction, before starting the works and obtaining the Engineer’s approval,
Verification of the mixtures preparation plant shall be done:
during the performance of the trial section
during aplication
This shall be consistent with the results obtained in the laboratory and all be to the Engineer approval.
The preparation and performance of the works, tests performance on the trial section, including the wheel tracking test, shall be done in the presence and with the Engineer’s approval.
The preparation, the works and tests performance on the trial section shall be done at the Contractor’s expense.
The changing of the method statement shall involve the performance of a new trial section.
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The results obtained on the trial section shall determine the method statement, and become a reference document for the layer performance.
Preparation of the support layer
Before the laying of the asphalt mixture, the surface shall be cleaned, using a mechanical brush, compressed air or, if necessary, washing with water under pressure.
When laying the bituminous surfaces, the working joints and the surface shall be primed with emulsion of cut back cationic bitumen, spread in thin layers. With approval of the Engineer, the primer may be omitted, when there is not more than 3 days between layers.
The priming of the support layer shall be carried out by a mechanical spray.
The quantity of the residual bitumen shall be (0.3-0.5) kg / mp.
The surface of the support layer on which the asphalt layers are to be placed, shall be dry.
The utilisation of any geo-grids, geo-textiles or geo-composites shall be made in accordance with the requirements of their Technical Agreements.
The transportation of the asphalt mixture
The asphalt mixture shall be transported in trucks with clean and dry tipper body, provided with tarpaulins to prevent the loss in temperature.
Laying the asphalt mixtures
Laying the asphalt mixture shall be by pavers-finishers having grading systems and assuring pre-compaction.
The laying of the asphalt mixtures shall be done when the ambient temperature is more than +10 C and for the asphalt mixtures stabilized with fibres (MASF) more than +15C.
Laying shall not be permitted during heavy rain.
During laying and compaction, the asphalt mixtures shall be the temperature in accordance with Table 14.
The laying of the asphalt mixtures shall be in one pass for the full width of the carriageway.
The preparation, transportation and laying shall be strictly co-ordinated to prevent creating day joints.
In case of interruptions that lead to the decrease in asphalt temperature below 120 C that remains non-compacted in the paver, the paver shall be removed from the working area, the surface will be immediately compacted and the remaining asphalt mixture removed from the site.
When laying works are resumed on the same lane or the adjacent lane, the areas related to the working joints, longitudinal and/or transversal, shall be cut on the entire thickness of the layer, so that a vertical edge will result. When the adjacent lanes are executed in the same day, for the longitudinal working joints the cutting is no longer necessary. The new surface resulted from the cutting shall be primed.
The longitudinal and transversal working joints of the layers shall be moved accordingly from the working joints of the previous layer by at least 10 cm.
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Compaction
The compaction of the asphalt mixtures shall be done with rubber-tyred rollers or smooth roller compactors, provided with appropriate vibrating devices, so that the technical characteristics provided in Table 10 be obtained.
The compactors shall operate without shocks, with a reduced speed at the beginning to avoid wave in the pavement.
The rubber-tyred rollers shall be equipped with protection aprons and shall stay no longer than 50 m behind the paver-finisher.
2.5.6 Control of the execution and acceptance of works
2.5.6.1 Verification of the geometrical elements
The geometrical elements and the maximum deviations for the geometrical elements shall comply with the conditions in Table 15.
Table 15
The measured element/ item The admissible deviation
Thickness of the layer ±10 %
Width of the layer ±5 cm
Slope of the transversal profile ±0,4 %
Height from datum line for the longitudinal and transversal profiles
±0,5 cm (respecting the designing scale)
Roughness (measured under the 3 m screed or similarly)
0,3 cm
2.5.6.2 Characteristics of the bituminous surface
The hot rolled bituminous surface shall comply with the technical conditions provided in Table 15.
2.5.6.3 Acceptance of works
After finishing the works on a section, the completed works shall be submitted for the Engineer’s approval, prior to laying the next layer.
The inspection of the works that are to be covered has to provide information to confirm whether the works have been executed in accordance with the design and the Technical Specifications.
The acceptance implies the verification of all records during execution and the tests results, together with the examination of the works.
Following the verification, a report shall be prepared in order to authorize the execution of the following phase.
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ANNEX A
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ANNEX B - TYPES OF MIXTURES FOR THE WEARING COURSE
No Technical class of the
road
Technical class of the
street
Wearing course Type of the asphalt mixture (1)
1 I I
Asphalt mixture stabilized with fibres MASF8, MASF16Asphalt concrete rich in chippings with modified bitumen BA16mRough asphalt concrete
- with modified bitumen BAR 16m- with bitumen with additives BAR 16a
2 II, III II, III
Asphalt mixture stabilized with fibres: MASF8, MASF16Rough asphalt concrete:
- with modified bitumen BAR16m- with bitumen with additives (2) BAR16a- with bitumen BA16
Asphalt concrete rich in chippings:- with modified bitumen BA16m- with bitumen with additives (2) BA16a- with bitumen BA16
3 IV, V IV
Mixtures stabilized with fibres; MASF8 and MASF16Asphalt concrete rich in chippings:
- with bitumen with additives (2)BA8a, BA16a, BA25a- with bitumenBA8, BA16, BA25
Asphalt concrete with crushed gravel (3)- with bitumen with additives BAPC16a- with bitumen BAPC16
Note : 1. The symbols for the asphalt mixture are those from Table 3.
2. The bitumen with additives is used when the bitumen adhesivity to natural aggregates is under the limit of 80%.
3. With the Road Administrator’s agreement.
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ANNEX C - TYPES OF MIXTURES FOR THE WEARING COURSE
No.Technical class of the
road
Technical class of the
street
The binder course Type of the asphalt mixture (1)
1 I, II I, II
Rough asphalt concrete with chippings:- with modified bitumen BAD25m- with bitumen with additives BAD25a- with bitumen BAD25
2 III III
Rough asphalt concrete with chippings:- with modified bitumen BAD25m- with bitumen with additives (2) BAD25a- with bitumen BAD25
Open graded asphalt with crushed gravel :- with bitumen with additives (2) BADPC25a- with bitumen BADPC25
3 IV, V IV
Rough asphalt concrete with chippings: - with bitumen with additives (2)BAD25a- with bitumen BAD25
Open graded asphalt with crushed gravel :- with bitumen with additives (2) BADPC25a- with bitumen BADPC25
Open graded asphalt with graded gravel:- with bitumen with additives (2) BADPS25a- with bitumen BADPS25
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ANNEX D - THE REFERENCES FOR DIFFERENT TYPES OF THE ASPHALT MIXTURES PROVIDED FOR THE EXECUTION OF THE HOT ROLLED BITUMINOUS SURFACES
No. Type of the asphalt mixture Reference
1.Asphalt mixtures stabilized with fibres: MASF8
MASF16
2.
Asphalt mixtures with bitumen modified with polymers- asphalt concrete rich in chippings - rough asphalt concrete- rough asphalt concrete with chippings
BA16mBAR16mBAR25m
3.
Asphalt mixtures with bitumen with additives- rough asphalt concrete rich in chippings
- rough asphalt concrete - asphalt concrete with crushed gravel - open graded asphalt: - with chippings - with crushed gravel - with sizeed gravel
BA8aBA16aBA25aBAR16aBAPC16a
BAD25aBADPC25aBADPS25a
4
Asphalt mixtures with non-paraffinic bitumen for roads - asphalt concrete rich in chippings
- rough asphalt concrete - asphalt concrete with crushed gravel - open graded asphalt: - with chippings; - with crushed gravel; - with sizeed gravel.
BA8 BA16 BA25 BAR16 BAPC16 BAD25 BADPC25 BADPS25
2.6 ROAD MARKING
2.6.1 General provisions
The Technical Specifications refer to the conditions for the execution of the road marking and includes the technical requirements, which have to be met.
The Contractor shall perform in an authorized laboratory all the tests and assessments requested by the Technical Specifications and any other tests required by the Engineer.
Apart from the Technical Specifications, the Contractor shall respect the stipulations of the standards and norms in force.
The Contractor shall make sure that by all execution method statements he fulfils the requirements of the Technical Specifications.
The Contractor shall record on a daily basis data regarding the execution of the works and the results further to tests and investigations.
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2.6.2 Materials
2.6.2.1 Technical conditions regarding marking
For the road markings the following materials shall be used:
White paint for marking, which is ecological, type plastic mass, single- component, diluted by water (without organic solvents) and dried up in air – for marking in continuous layer or in structured model.
This paint shall ensure visibility irrespective of conditions. The paint shall be executed over suitable priming coat. The liability in exploitation of the road marking shall be of minimum 18 month. The quality of the paint shall be established according to the technical specifications as indicated in Annex 1. The quality of priming coat shall be established in compliance with the “Technical NOTE” indicated in Annex 2.
The Contractor shall present to the Engineer the technical agreement for all the materials, which he intends to use and for which he has to obtain the Engineer’s approval.
The Quality Certificates issued by international laboratories [at least equivalent with BAST (microballs) and LGA (paint)] shall be enclosed to the materials.
2.6.2.2 Quality control of the paint for road marking
Sampling and testing shall be carried out according to the stipulations of the Technical Instructions for Road Marking NAR-CESTRIN.
2.6.3 Types of road marking
2.6.3.1 Longitudinal marking
The longitudinal road marking are generally classified as follows:
Marking to separate the traffic direction on two traffic lane roads;
Marking to separate the traffic lanes;
Marking to separate the carriageway.
These markings are indicated by:
Simple or double continuous line;
Simple or double interrupted line;
Double line composed of a continuous line and an interrupted one.
Longitudinal marking to separate the traffic direction on two traffic lane roads
One single interrupted line, with spaces between segments according to the road condition;
One continuous line and an interrupted one, joined each other, which allows overtaking only for the traffic direction along the interrupted line;
One double continuous line, which not allows overtaking irrespective of the traffic direction.
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Marking to separate the traffic lanes
One interrupted line, with spaces between segments according to the road conditions.
Marking to separate the carriageway
Simple continuous lines on highways, national roads and on the exterior of dangerous bends;
Simple interrupted lines that mark the acceleration, deceleration lanes and the turning lane
Marking for widening in bends
For widening < 1m, all the widening shall be marked on the interior side of the bend;
For widening > 1m, the interior side of the bend shall be marked with 1m + 60% of the remaining widening more than 1 m and the exterior traffic lane shall be marked with 40% of what is left over 1 m.
2.6.3.2 Transverse marking
Marking for stopping
Continuous line with the width of 400 mm
Marking “Allow crossing”
Discontinuous line with a width of 400 mm, which can be preceded by a triangle
Marking for pedestrian crossings
Lines with 400mm width at 1.0 m distance, parallel with the centre line;
- lines with 3000mm length for a speed < 50 km/hour;
- lines with 4000mm length for a speed 50km/hour.
Stopping lines with 400mm width, transverse on the centre line, shall be marked 600mm before the pedestrian crossing for each traffic lane.
Marking for bicycles
Two interrupted lines.
2.6.3.3 Other marking
Guiding road marking
Utilized to indicate the direction, which the vehicles shall follow in the junction.
Marking for prohibited areas
Parallel inclined lines framed by a continuous contour line.
Marking for parking areas
at 90o on the line, which separates the edge of the road;
inclined on the line, which separates the edge of the road;
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parallel with the line, which separates the edge of the road;
Marking for dangerous bends that follows a long road alignment
marking to reduce the speed, the width is 400 mm
Marking using arrows and lettering
This marking indicates the destination of the slope upwards, speed limitation and have different dimensions according to the area where applicable and the approaching speed.
The color for these road markings is white.
The road markings shall be, generally, executed mechanically using adequate equipment. The marking by arrows, lettering, symbols as well as other marking with reduces surface can be manually executed using suitable templates.
2.6.4 Execution of the road marking
Before starting the marking works, a trial section shall be performed, having minimum 200 m length. The passing to the performance itself shall be done only after the Engineer gives his approval for the trial section.
The road marking executed using white marking paint, which is ecological, contains a single component and is diluted by water, shall ensure the visibility irrespective of situations (night and day). The paint shall be executed over an appropriate primer.
The thickness of the marking film shall be of 600mm.
When executing the road marking using paint, the surface of the carriageway shall be perfectly dry and at a minimum temperature of +15o C.
Preparatory works
The road marking shall start only after the Contractor has obtained the necessary approvals.
Spotting out the road marking
The spotting out of the points shall be carried out using suitable equipment;
The surfaces shall be cleaned and dried before starting the execution of the road marking;
The surfaces, which are already marked shall be mechanically cleaned;
The primer and the paint shall be coat according to the instructions from the manufacturer;
The Engineer shall verify the spotting out before the execution of the permanent road marking.
When executing the road marking, accounted shall be taken the following:
The type of the road pavement and the roughness of the surface;
The updated book for the road marking (marking film);
Road marking method statement (pre-marking, preparation of the equipment, preparation of the surface, preparation of the paint);
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Dosage of paint, dosage of the micro balls.
Execution of the works shall be carried out according to the instructions from the manufacturer, as follows:
Pre-signing of the works;
Marking;
Cones placing to protect the wet paint;
Protection of the wet paint in order to not occur deterioration of the road marking by the time it dries;
Recovering the cones.
The road marking shall be signalled using signs and lightning warning devices.
The road marking shall be done minimize any effect on the continuity of the traffic flow.
Each category of marking shall be executed according to STAS 1848/7-85.
During the execution of the road marking there shall be performed verifications of the dosage of both paint and micro balls.
The marking strip shall have an even contour, with micro balls uniformly distributed over the length and width of the paint strip.
2.6.5 Control of execution and acceptance of works
The Contractor shall submit for the Engineer’s approval the execution method statement for the road marking not less than 14 days before starting the works.
This shall contain, without being limited to, the following:
Measures that ensure an homogenous content of the paint
Periodic verification of the thickness of the paint film and of the quantity and distribution of the micro balls.
The quality control of the paint and micro balls shall be performed in a laboratory authorized by the Employer and the tests shall be at the Contractor’s expense.
The Contractor shall respect the dosage as indicated by the authorized laboratory, which are updated according to the traffic, type and characteristics of the road surface, type of paint and surrounding conditions.
Acceptance of the Road Marking
When accepting the works, verification shall be carried out as follows:
Lay out of the marking, according to the stipulations of STAS 1848/7-85
Dosage of paint and micro balls as well as the thickness of wet film, as well as of the dry film.
ANNEX 1
Technical record – White paint for making, ecological, single component, diluted by water (without organic solvents), reflective on dry and wet surfaces
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Characteristics of liquid paint
Type of binding acrylic
density according to the manufacturer
non-volatile substances minimum 85%
viscosity according to the manufacturer
ash % at 450oC according to the manufacturer
duration of storage minimum 6 month
Characteristics of the film
Bulletin BAST min 4 Mio for a wet film
Thickness of the film 2000 mm (wearing test)
report BAST no.
retro-reflection minimum 150 mcd/Lx/m2
on a wet surface
luminosity factor minimum 0,40
SRT minimum 40
Wearing resistance minimum 85%
Thickness of wet film 2000 mm
Type of micro balls bulletin BAST
Dosage of micro balls g/m2 bulletin BAST
Time for drying up bulletin BAST Effect of the rain after drying according to the manufacturer
Guarantee for paint and micro balls
Paint bulletin LGA - BAST
Micro balls Lloyd certificate or from another European laboratory, agreed by the Employer
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Conditions for execution
Temperature for execution
air according to the manufacturer
ground according to the manufacturer
Hygrometry according to the manufacturer
Dilution according to the manufacturer
Marking vehicle according to the manufacturer
Toxicity and protection of the environment according to regulation 91/155/EWG
Specifications for transport, processing according to the manufacturer and safety storage
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ANNEX 2
Technical record – Primer that dries under the effect of air
It is used to ensure the adherence of the paint to the road surface, for the permanent marking. The primer shall be executed over the bituminous surfaces, both existing and new or over the old road marking.
Characteristics of the primer:
Type of binding acrylic
Density according to the manufacturer
Viscosity according to the manufacturer
Duration of storage minimum 6 month
Conditions for execution:
Temperature of the air according to the manufacturer
Temperature of the surface according to the manufacturer
Relative humidity % according to the manufacturer
Execution method according to the manufacturer
Thickness of wet film according to the manufacturer
Time for drying maxim 3-6 minutes
Effect of the rain after drying maxim 15 minutes
Toxicity and protection of the environment according to stipulation 91/155EWG
Specifications for transport, processing according to the manufacturer
and safety storage
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2.7 ROAD SIGNING
2.7.1 General provisions
The Technical Specifications refer to manufacturing, mounting as well as to the acceptance of the road signs. It includes classifications according to size, images, shape and technical recommendation, which have to be met.
All the traffic signs shall comply with the stipulations of STAS 1848/1, 2 and 3-86.
The Contractor shall perform in an authorized laboratory all the tests and assessments requested by the Technical specifications and any other test required by the Engineer.
Apart from the Technical Specifications, the Contractor shall respect the stipulations of the standards and norms in force.
The Contractor shall make sure that by all the execution method statements, he fulfils the requirements for the Technical Specifications.
The Contractor shall record on a daily basis data regarding the execution of the works and the results further to measurements, tests and investigations.
2.7.2 Types of signs, sizes
2.7.2.1 Type of Signs
Warning Signs
Are: - equilateral triangles with red frame, showing a black symbol on a white background
- rectangular or red arrow, indicating the direction of the bend, on white background
Regulatory Signs
Priority: White arrows in red frame;
White equilateral triangle in red frame;
Red octagon with STOP in white;
Yellow square in white frame to indicate priority road;
Circle in red frame with two arrows, one red the other white;
Square on blue background with two arrows, one red the other white
Prohibitory or restrictive signs Circle in red frame with black or red engravings on white or blue background
Obligatory signs: Circle with white symbols on blue background.
Directional and information signs
Are rectangular or arrow shape panels, with lettering and symbols on background:
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Green for motorways;
Blue for other roads;
Yellow for temporary diversions.
Directional Signs: Rectangular or arrow shape, lettered (localities name, etc.), white colored on green or blue background.
Information signs: Square or rectangular shape, on blue background, with symbols for utilities: pedestrian crossing, first aid point, motorway, restaurant, telephone, services etc.
The signs that precede the junctions on a motorway, designating the name of destinations which are reached by other class of roads, are to be on a blue background in a white frame, within the green background of the sign.
Additional signs: Rectangular or square shape mounted under the signs to draw the drivers’ attention to some features of the road section.
2.7.2.2 Size of the signs
The size of the signs shall comply with STAS 1848/1-86 and 1848/2-86.
On the motorway and for the junctions, very big size indicators shall be used. For the other roads, big size indicators shall be used.
2.7.3 Manufacture the signs
All the signs shall be manufactured using aluminium, with the size and shapes as indicated.
The signs in shape of triangle, round or rectangular with the maximum size less than 1m, and those in shape of an arrow, shall be executed of aluminium sheet with a minimum thickness of 2mm, with the frame reinforced by double bending.
The rectangular or square panels, with the smallest size greater or equal to 1m, shall be braced with aluminium, vertically joined.
The aluminium shall be in accordance with:
For sheet: 99,5 HD (according to Romanian standards)
For sections: ALMGSI-0,5 F 22 (according to DIN)
The fixing shall be executed using screws. The screws and all parts used for mounting on poles shall be protected against corrosion.
The rear of the sign panels and the double bent zone (“rebordul”) shall be painted in grey.
The margins of the indicators will be double-thickness.
The preparation of the surface of the signs prior to the application of the retro-reflective film shall be carried out according to the recommendations from the film manufacturer.
The types of retro-reflective material applied on road signs are:
Class 3 – „diamond”- for motorways;
Class 2 – „high intensity” – for European roads;
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Class 1 – “engineering grade” – for other roads.
In case of using the “diamond” film, taking into account the rigidity of the film, it is recommended that a transparent coloured film is used for the background for the indicators with inscriptions. Lettering and symbols are cut from this coloured film and laid over sheets of “diamond” film.
For the regular signs (triangle, circle, rhombi, square) the engraving shall be executed by serigraphy.
2.7.4 Manufacture and painting the poles
For the poles that support triangle, round and arrow shapes panels, as well as for the square or rectangular panels with the maximum dimension less than 1m, steel tubes with a minimum thickness of 3mm and diameter between 48-51mm shall be used or poles type .
The Contractor may propose for the Engineer’s approval alternative type of poles.
As supporting devices for panels with the minimum dimension more than 1m, steel tubes or sections shall be used; the size shall vary according to the surface area of the panel.
The characteristics of the panels shall be shown on the Drawings.
The poles shall be cast in a concrete C 6/7,5 foundation.
The supporting elements for the panels shall be painted in grey, including all necessary primers and undercoats.
2.7.5 Control of execution and acceptance of works
The three classes of retro-reflective films utilized in Romania are:
Class 1 - „Engineering grade”, composed of micro balls made of glass, incorporated in a transparent material based on resin
The film has an adhesive on both sides and is applied under cold or heat;
Class 2 - „High intensity”, as Class 1, with a layer of air between the micro balls layer and the external side of the film
Class 3 - „Diamond”, as Class 2, but with glass prisms instead of micro balls.
The tests consist of:
Photometrical analysis;
Mechanical tests
Resistance to aggressive agents.
For all films submitted for the Engineer’s approval, the Contractor shall present the technical agreement.
The processing and application of the retro-reflective films shall be carried out in compliance with the manufacturer instructions.
The film samples for testing shall be placed on aluminium plates of 2mm thickness, kept at a temperature of 23 oC 2oC and relative humidity of 50% 5%, 24 hours prior to testing.
The results of the tests are given as an average of at least 3 sets of results of 3 samples tested in similar conditions.
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2.7.5.1 Photometrical analysis
Determining the retro-reflection coefficient R
The retro-reflection coefficient R allows the determination of the visibility level during night-time. It is given in Cd/lux/m2
The tests shall be performed on samples of 150 mm x 150 mm, at an incidence angle of the lightning source of 5o, 30o and 40o to the perpendicular on the film, and at reception angle de 0,2o, 0,33o, 1o, 2o
towards the incident fascicle.
The retro-reflection coefficient R shall be measured in accordance with CIE no.54/1982 – Retro-reflection for the light source A (temperature of the colour 2856o K shall be given in cd/lux/m2). The value R shall be an average of the determinations in different points on the surface of the sample. The minimum allowed values are indicated in tables A1 and A2. For the white films with transparent colours, R shall be at least 70% of the values of R for coloured films indicated in tables A1 and A2.
Table A1: Minimum ratio R of retro-reflection [Cd/Lux/m2]Luminance: CIE – Standard of luminance A
White Yellow Red Green Blue Brown OrangeFilms class 1
0.2o5o 70 50 14,5 9 4 1 2530o 30 22 6 3,5 1,7 0,3 740o 10 7 4 1,5 0,5 0,1 2,2
0.33o5o 50 35 10 7 2 0,6 2030o 24 16 4 3 1 0,2 4,540o 9 6 1,8 1,2 0,4 - 2,2
1o5o 12 7,5 2 1,5 0,5 0,2 1,730o 6 3,5 1 0,7 0,2 0,1 1,040o 2 1 0,7 0,5 0,1 - 0,7
2o5o 5 3 0,8 0,6 0,2 - 1,230o 2,5 1,5 0,4 1,3 0,1 - 0,640o 1,5 1 0,3 0,2 - - 0,4
Films class 2
0.2o5o 250 170 45 45 20 12 10030o 150 100 25 25 11 8,5 6040o 110 70 15 12 8 5 29
0.33o5o 180 122 25 21 14 8,5 6530o 100 67 14 12 8 5 4040o 95 64 13 11 7 3 20
1o5o 15 9 2,5 2 0,5 0,4 4,530o 7,5 4,5 1,5 1 0,3 0,2 2,540o 4,5 3 1 0,5 0,2 0,1 2
2o5o 5 3 0,8 0,6 0,2 0,2 1,530o 2,5 1,5 0,4 0,3 0,1 0,1 0,940o 1,5 1 0,3 0,2 - - 0,8
Table A2: Minimum coefficient of retro-reflection for white colour – films class 3
= 5oo 0,33 0,5 1,0 1,5 2,0
R 310 280 70 18 6,2
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= 15oo 0,33 0,5 1,0 1,5 2,0
R 300 230 65 17 4,7
= 30oo 0,33 0,5 1,0 1,5 2,0
R 150 100 31 9 3,5
= 40oo 0,33 0,5 1,0 1,5 2,0
R 83 50 13 4 1,7
Minimum coefficient of retro-reflection compared with the white colour for film class 3:
Yellow Red Orange Blue Green Green2
Ratio to white colour
0,8 0,25 0,5 0,05 0,1 0,07
For the yellow films with enamel transparent red, R shall be of at least 50% of the value for the red colour indicated in tables A1 and A2.
The purpose of the tests is to:
Measure the visibility during night-time;
Evaluate the deterioration in time of the retro-reflection for different environment conditions;
Establish the level of the retro-reflection at the end of the Defects liability period;
Establish the frequency of the replacement of the signs;
Evaluate the general behavior of the serigraph retro-reflection films with transparent ink
Colour
The colour of the retro-reflective films shall be determined on samples of 50x50 mm applied on aluminium plates. The colour shall be measured using a colorimeter, according to CIE no. 15.2, 1986. The sample shall be illuminated using a standard source D 65, at a 45o angle with the perpendicular of the sample and with a measuring direction of 0o (measurement geometry 45/0).
For the reflective films of different colours, the colour span is determined from the co-ordinates of the corner points of the diagram CIE 1931. The tables B1, B2 and B3 indicate the chromatic field for new retro-reflective films.
Chromatic co-ordinatesTable B1 – Films class 1 and 2
Chromatic colour1 2 3 4
WhiteX 0,305 0,335 0,325 0,295Y 0,315 0,345 0,355 0,325
YellowX 0,494 0,470 0,513 0,545Y 0,505 0,480 0,437 0,454
RedX 0,660 0,610 0,638 0,690Y 0,340 0,340 0,312 0,310
Green X 0,110 0,170 0,170 0,110
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Chromatic colour1 2 3 4
Y 0,415 0,415 0,500 0,500
BlueX 0,130 0,160 0,160 0,130Y 0,090 0,090 0,140 0,140
Table B2 - Films class 3 – daytime Chromatic color Luminosity
factor1 2 3 4
WhiteX 0,305 0,335 0,325 0,295
>/- 0,40Y 0,315 0,345 0,335 0,325
YellowX 0,494 0,470 0,513 0,545
>/- 0,24Y 0,505 0,480 0,437 0,454
RedX 0,735 0,700 0,610 0,660
>/- 0,03Y 0,265 0,250 0,340 0,340
OrangeX 0,610 0,535 0,506 0,570
>/- 0,12Y 0,390 0,375 0,404 0,429
Green X 0,110 0,170 0,170 0,110
>/- 0,03Y 0,415 0,415 0,500 0,500
Green2X 0,170 0,220 0,245 0,210
>/- 0,01Y 0,525 0,450 0,480 0,550
BlueX 0,130 0,160 0,160 0,130
>/- 0,01Y 0,090 0,090 0,140 0,140
Table B3 – Films class 3 – night-timeChromatic color
1 2 3 4
WhiteX 0,475 0,360 0,369 0,515Y 0,452 0,415 0,370 0,409
YellowX 0,513 0,500 0,545 0,575Y 0,487 0,470 0,425 0,425
RedX 0,652 0,620 0,712 0,735Y 0,348 0,348 0,255 0,265
OrangeX 0,645 0,613 0,565 0,595Y 0,355 0,355 0,405 0,405
GreenX 0,007 0,200 0,322 0,193Y 0,570 0,500 0,590 0,782
Green 2X 0,007 0,200 0,322 0,193Y 0,570 0,500 0,590 0,782
BlueX 0,033 0,180 0,230 0,091Y 0,370 0,370 0,240 0,133
Table C – Chromatic Co-ordinates for grey and black films non-retro-reflective
Chromatic colour Illuminating factor1 2 3 4 Maxim Minim
GreyX 0,305 0,350 0,340 0,295
0,08 0,10Y 0,315 0,360 0,370 0,325
BlackX 0,300 0,385 0,345 0,260
< 0,02 < 0,02Y 0,270 0,355 0,395 0,320
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2.7.5.2 Mechanical characteristics
Adherence to support
The retro-reflective films has to present a very good adherence to the support.
The test consists of checking samples of 100x150 mm; the film will be removed with a blade on a surface of 20x20 mm; the rest of the film will be manually removed; the adherence is considered as satisfactory if the film is destroyed during removal.
Resistance to shocks
The test consists of checking samples of 150x150 mm; A steel ball having 51 mm diameter and 540 g weight falls from a high of 250 mm; the film is considered satisfactory if there are no visible fissures and/or removals.
2.7.5.3 Verifying the resistance against environment agents
Resistance to dry hot weather conditions
The samples having 75 x 150 mm will be maintained for 24 hours in the drying closet at the temperature of 71 ± 3 C, then they are re-conditionned for 2 hours at the room temperature, after which the test can be interpreted. It will be considered as satisfactory if the sample does not have defects as fissures, barkings or removals from the support.
Resistance to coldness
The samples, having dimensions of 75 x 150 mm will be maintained for 72 hours in the refrigerator at the temperature of -35 ± 3 C, after which they are re-conditionned for 2 hours at the room temperature and then the test is interpreted. The test is considered as satisfactory if the sample do not have defects as fissures, barkings or removals from the support.
Resistance to corrosion
A 5% potassium chloride is dissolved in distilled water at a temperature of 35 oC 2oC. Samples of 150x150 mm will be sprayed with salt solution in 2 cycles of 22 hours each.
After each cycle, the samples will be dried at room temperature for at least 2 hours.
In order to study the samples they will be washed with distilled water and then dried.
The film is considered suitable if it does not show visible deterioration of the surface and the retro-reflective ratio and the chromatic fields are according to Tables A, B and C.
Resistance to bad weather action
The samples will be placed in different climatic areas for a 2 years period, facing South and inclined at 45 o. The surfaces will be periodically washed to remove the dust.
The test result is inappropriate if deterioration of the surface is visible (i.e. bubbles, barks, cracks and detachment from the support)
The retro-reflective ratio for the angle = 0.33o and = 5o is less than the values of Table A multiplied by the following indices:
Class 1 Film 50%
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Class 2 Film 80%
Class 3 Film the values of the retro-reflective ratio are less than the values from Table D:
Table D
o o ColourWhite Yellow Red Orange Blue Green Green2
0,33 5 248 198 62 124 12 25 170,33 30 120 96 30 60 6 12 81 5 56 45 14 28 3 6 41 30 25 20 6 13 1,3 2,5 1,8
The chromatic values are outside the colour fields no. 3 and 4.
The illuminating factors are smaller than the minimal values from Table C.
2.7.5.4 Control of the execution of the panels
The Contractor shall provide to the Engineer the technical agreement and the Certificate of Quality for each type of film that are to be approved by the Engineer.
When executing the traffic signs made of retro-reflective films, they shall be applied on the aluminium support according to the recommendation from the manufacturer. In case there are used painted supports, the paint shall have a high resistance to exterior conditions.
The Certificate of Quality shall indicate the results for the exposure test for 5 years under atmospheric conditions.
On the back of the sign panels, the following shall be marked clearly and durably:
Identification data of either the manufacturer or the seller;
Type of reflective material used;
Date when the panel is assembled.
2.7.5.5 Acceptance of works
After completing the signing this shall be submitted for the Engineer’s approval.
An acceptance note shall be concluded further to verification.
2.8 CULVERTS
2.8.1 General
Culverts are structures with spans less than or equal to 5.00 m.
The clear span of the culvert shall be established on the basis of a hydrological design according to the Department Norms for the hydrological design of bridges and culverts PD 95-77.
The width of the road on the culvert shall be equal to that of the adjacent road and the minimum depth to the crown of the culvert shall be that of the formation. No sidewalk shall be constructed on the culvert, except in the case of existing sidewalks which are to be continued.
The load train for the calculation of the culvert is the same as for bridges, according to STAS 1545-89 “Road bridges and foot bridges. Actions” and STAS 3221-86 “Road bridges. Classes of loading trains”.
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Depending on the position of the road formation, the culverts may be divided into:
open culverts - with the road platform directly on the superstructure;
buried culverts - placed in the body of the embankment, minimum 50 cm deep, under the road formation.
Depending on the shape and method of construction, culverts may be divided into: slab-, ovoid- or pipe culverts, cast in situ or pre-cast units.
Any system chosen must satisfy the hydrological design and ensure safe service and easy maintenance.
The construction of the culvert is carried-out on the basis of the design carried out by an authorised design office and approved by the Engineer.
The components of the culverts (sub and superstructure) shall be built observing the same rules as for the construction of bridges. The foundation, formwork, reinforcement, concrete work and non-centering must meet the requirements of the project.
Pre-cast units, made on the site or in a factory, shall have quality certificates. The Engineer shall be informed of any deviation from the provisions of the project or of the Technical Specifications.
Any remedial work necessary following the transport handling or erection of the pre-cast units shall be performed on the basis of a method proposed by the Contractor and approved by the Engineer. The works shall be inspected by the Engineer before covering.
The design of the culvert must be appropriate to the conditions of the site and the type of project.
The construction of culverts involve the following operations:
construction of a work platform;
excavation and support of excavation faces;
foundation construction;
construction of abutments, slabs, pre-cast units;
construction of drainage behind the abutments and pre-cast elements.
2.8.2 Description of operations
2.8.2.1 The Work Area Execution
The position and size of the work area are determined by the local conditions, length and width of the culvert. The Contractor shall size the area such that all works can be performed without problems.
2.8.2.2 Excavation and Support of Excavation
Manual or mechanical methods may be used for the excavation. It may be necessary to provide support of the excavation to avoid collapse and landslides.
When excavation uncovers existing underground utilities (water, gas, electricity, etc.) which are to remain in operation, appropriate measures shall be taken in order to protect them from deterioration. The works shall be suspended and the Engineer shall be informed, so that he can take the necessary steps for protection of the service.
After excavation, an inspection report will be drawn up, regarding the foundation level and the soil characteristics. The excavated soil shall be removed to a storage place approved by the Engineer.
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2.8.2.3 Foundation construction
The last 0.25 m of the excavation, below the final foundation level, shall be executed in presence of the Engineer. The concrete shall be poured immediately after excavation against the walls of the resulting excavation. The supports will be dismantled at the same time as the concrete is poured.
Concrete shall be poured without any interruption, in 200 – 500 mm thick layers, up to the design level, by means of metal or wood chutes, according to the Practice code for the execution of concrete, reinforced concrete and pre-stressed concrete works, indicative NE 012 - 99.
Permissible free fall of the concrete shall be less than 1.5m and construction joints shall be avoided.
2.8.2.4 Wall and slab construction
Cast in-situ reinforced concrete abutments of culverts.
The main operations include the following:
the installation of reinforcement
wall shuttering in accordance with the design provisions
pouring and vibration of the concrete. The concrete class should be according to the design specifications
Prior to the pouring of concrete into the shuttering it is necessary to check:
the sizes in plan and the levels of the excavations;
the vertical position of the shutters and the provision of measures for keeping their shape and assuring the tightness;
the provision of a concrete compacting plant;
the cleanliness of shutters and reinforcement.
In order to avoid the occurrence of any internal stresses due to contraction and heat dissipation, the use of concrete grades with aggregates featuring a maximum diameter as large as possible is recommended, and rigorous control of the Water/Cement (W/C) ratio should be undertaken.
The concrete workability shall be established in accordance with the proposed methods of delivery and placement.
The removal of the shutters shall take place after the concrete has hardened sufficiently to keep its required geometrical shape. The minimum time for removal of the shutters depends on the cement type used in the concrete and on the ambient temperature.
The removal of shuttering follows the reverse sequence of shuttering installation. This operation shall be carefully executed so that the edges and the surfaces are not damaged. The possible defects of the concrete shall be corrected after inspection by the Engineer.
The shuttering removal time shall be established in accordance with the Practice code for the execution of concrete, reinforced concrete and pre-stressed concrete works, indicative NE 012-99.
2.8.2.5 Pre-cast unit walls and slabs
The pre-cast units needed are:
slabs with a length according to the width of the culverts;
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wing walls with heights according to the free height of the culvert;
rectangular pre-cast units with the span of 2.0 m;
pre-cast headwalls.
The pre-cast elements shall be laid on a grade M100 cement mortar which shall be well mixed and uniform.
The joints of the pre-cast units shall be filled with cement mortar.
A grading concrete should be laid on top of the pre-cast slabs prior to waterproofing.
The waterproofing on the horizontal surfaces consists of a normal bridge waterproofing material. On vertical faces waterproofing shall consist of 3 layers of cationic bitumen emulsion.
2.8.2.6 Execution of the drain behind the abutments and the pre-cast elements
In order to protect against water build up, the cast in–situ concrete abutments and pre-cast units have drains installed behind them. The weep holes in the wing wall allow discharge of the water collected by the drains.
The drain shall be of crushed stone, gravel or ballast masonry, according to the details in the design.
2.8.2.7 Monolith headwalls
The monolith headwalls are cast-in situ concrete elements, fixed by the pre-cast unit or monolith abutments with metal fixing elements (screws) or reinforcement steel bars. The headwall shall be executed all the dimensions in accordance with the drawings.
2.8.3 Materials – quality requirements
2.8.3.1 Water
Water for mixing concrete shall be free from materials that affect hydration of the cement.
The water used to prepare the concrete may be taken from public supply or from other sources. The Water from all sources shall be checked for compliance with the technical requirements provided in STAS 790-84.
The water shall be tested at the beginning of the works and the tests shall be repeated whenever a change of the water characteristics is noticed.
The water to be used on the site shall be protected against contamination by detergent, organic matters, oils, clay etc.
2.8.3.2 Cement
Cement specified for the concrete in the design will be used and shall comply with the quality conditions in the code.
2.8.3.3 Aggregates
To prepare the cast-in-place concrete and the drain, ballast, sand, crushed stone, gravel (that corresponds to the quality requirements of STAS 1667/76, STAS 4606/80, STAS 662/89, SR 667/1997) will be used.
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2.8.3.4 Shutters
The stock shutters are industrially made and the following conditions must be met.
shapes and sizes required by the design;
sufficiently watertight to prevent the loss of cement slurry;
stable and resistant to the loadings imposed by the concrete;
erection with assembly pieces;
lubrication of the surfaces that have contact with the concrete;
removal of shuttering to permit a gradual transfer of loading to the constructed elements.
2.8.3.5 Rubble stone
The rubble stone for construction of masonry for drains:
the stone dimensions shall between 150 and 250 mm
the maximum dimension shall not be more than 2.5 greater than the minimum dimension
stones shall not be frost susceptible
before being placed, the stones shall be washed to remove soil and other impurities.
2.8.3.6 Concrete
The grade of the concrete is shown on the drawings. The minimum concrete classes are established according to the Practice code for execution of concrete, reinforced concrete and pre-stressed concrete works", indicative NE 012-99.
2.8.3.7 Reinforcement
For the reinforcement, OB 37 and PC 52 steel shall meet the requirements of 438/1-89 STAS.
For the structural reinforcement, only one of those 2 types of steel is used, and the use of steel of different grades in the same section is not permitted.
2.8.3.8 Quality Checking
Work platform.
The following elements are checked:
the setting out of the working platform.
water drainage systems for use during construction;
Excavation and trench supports
The following shall be checked:
the setting out and alignment;
the foundation level and soil characteristics;
the measures for the protection of work and traffic safety;
correlation between site characteristics and these assumed during design;
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details of the necessary falsework
Shutter installation
When the shutters have been erected, the following shall be checked:
adequate support;
connection between shutters;
position, level and internal dimensions of the shutters;
cleanliness.
Reinforcement Assembly
When the reinforcement has been fixed, the following shall be checked:
type of steel and bar diameters;
number of bars and shapes;
rigidity and cleanliness;
cover to the shuttering.
Concreting
Check items to be carried out for fresh and hardened concrete:
concrete vibration;
the temperature of the fresh concrete which must be higher than 5oC when placed;
the fresh concrete quality - by taking samples;
concrete workability;
at the concrete plant a sample is taken at changes of shift and changes of the type of concrete;
the concrete quality shall be in accordance with the results from the trials, the class checking tests and the interpretation of the non destructive or core test results;
the maximum time of transport depending upon the temperature and quality of the concrete used.
Removal of shutters
After shutters have been removed, the following shall be checked:
appearance and surface finish;
the abutments sizes;
Drain
The drain behind the abutments and pre-cast units shall be checked for the following:
proper operation of weep holes and the drain;
the drain sizes;
the quality of the materials.
These checks are to be carried out according to “Practice code for execution of concrete, reinforced concrete and pre-stressed concrete works" indicative NE 012-99 and according to Law no. 10/95 and on
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the basis of "Programme for the works quality control". The designer, the beneficiary and the Contractor have agreed to all these checks. A report giving details of the necessary falsework and a report of the quality acceptance shall be produced.
2.9 CONSOLIDATION WORKS
2.9.1 Slope protection
2.9.1.1 General data
This work is measured in square meters of protected slope. This protection work is to prevent erosion and scouring of the slope. It shall be carried out on stable slopes which are liable to be eroded and scoured by rain water.
The protection of the slope shall be performed as follows:
using top soil;
using geogrids and top soil;
using geo-cells and top soil.
2.9.1.2 Slope protection of the surface with geogrids
The protection with geogrids shall be carried out on the finished slope surface and consists of the following operations:
transportation of the geogrid to the top of the slope;
fixing of the geogrid at the top of the slope using pegs made from reinforcing steel;
the geogrid shall be laid down the slope ;
top soil of 20 – 30 mm thickness shall be layed ;
grass seeding;
compaction of the surface using a hand roller;
water the sown surface until grass germination begins.
2.9.1.3 Slope protection of the surface with geo-cells
The protection with geo-cells shall be carried out on the finished slope surface and consists of the following operations:
transportation of the geo-cells to the top of the slope;
fixing the geo-cells at the top of the slope using pegs made from reinforcing steel;
the geo-cells shall be laid down the slope;
top soil of 100 mm thickness shall be laid;
grass seeding;
compaction of the surface using a hand roller;
watering the sown surface until grass germination begins.
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2.9.1.4 Materials – quality requirements
Topsoil
Topsoil arising from topsoil strip of the works area or brought from natural deposits shall be used. This material shall not contain lumps greater than 50 mm or metal or wooden intrusions or stones. Topsoil, when laid, shall have a water content of 18-22%.
Water
Shall comply with the requirements of STAS 790/84, if it is not obtained from the public networks.
Seeds
Shall be obtained from approved sources. They shall be specific to the area where they are to be used and shall be selected in accordance with the nature of the soil.
The seeds used in Romania belong to the graminaceous family, such as:
Lolium perene;
Poa pratensis;
Festuca rubra;
Festuca amudinacea;
Bromus inermis;
Agropyum cristatum.
The Contractor shall submit the seed type that he intends to use to the Engineer for approval.
Cellular geogrids and geo-cells
Shall have the shape, size and number of meshes per m2 given in the design and they shall comply with the quality conditions specified in the Quality Certificate. They shall be approved in Romania.
Fixing pegs
Are made of reinforcing steel and shall comply with the shape and the sizes shown on drawings.
2.9.1.5 Quality checking
Benches
The construction of the benches over the whole surface shall be checked, together with their alignment, levels and dimensions in accordance with the design and this Specification.
Laying of the topsoil
Topsoil shall be checked by testing one sample every 100 m.
The protected surface overall shall have no unevenness greater than 100 mm. To rectify the surfaces, the banks shall be cut and holes filled with topsoil.
Cellular geogrids and geo-cells mounting
The geogrids and the geo-cells shall be stretched on the surface in such a way that creases do not appear.
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Seeding the surfaces
The quality checks shall be visual inspections in order to obtain a uniformly dense grass covering. If, after the grass seed germinates, areas without grass are found, additional seeding shall be carried out.
2.9.2 Reinforced soil embankment walls
2.9.2.1 General data
The construction procedure consists of 3 main activities, which are carried out consecutively:
preparatory works of drainage, levelling and compaction of supporting ground
the placing of pre-cast units of reinforced concrete and geogrids at the base of the filling between the layers of local material
construction of layers of granulated material (laying, compaction and slope shaping).
2.9.2.2 Description of operations
Preparatory works
Preparatory works consist of:
setting out the work platform;
construction of the work platform which consists of the following stages:
- stripping the topsoil and storage outside the work area;
- excavation to the design profile and to falls;
- removal of excavated material to stockpiles approved by the Engineer;
- levelling of the site and compaction of the road bed to a degree of compaction of ID = 95%;
- placing of the first layer of geogrid;
- placing of the local soil layer and compaction to a minimum of 98%.
Placing of pre-cast elements of reinforced concrete and of the geogrids
The pre-cast concrete units shall be placed according to the design details, at the specified level and position. They shall be handled by mechanical means, suspended from three points.
During construction, the Contractor shall check safety precautions specified for the works near and under transport and lifting devices.
For the ease of the vertical face construction, the pre-cast elements have notches in the top and bottom. The pre-cast elements shall be positioned according to the design details.
For inclined facing construction, there is no need for these notches.
The horizontal space between the layers of the concrete elements shall be soiled and seeded.
Where features on the concrete face are required for aesthetic purposes, the shape will be formed by attaching formers to the inside of the shutters (timber strips, trapezoidal or round form etc.).
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The geogrids to be laid into the wall shall comply with the design details.
Geogrids shall be laid in a single direction with a 200 mm overlap and shall be stretched manually to eliminate creases and relieve stresses.
The geogrids shall be placed flat with the strongest fibres in the direction given in the design.
Geogrids shall be fixed in position by metal pins.
Filling for the reinforced soil wall construction
The filling shall be laid directly over the geogrid with laying equipment such that the wheels or tracks are separated from the geogrid by a layer of drained fill at least 200 mm thick.
The layers of local material shall be placed horizontally and compacted to a thickness of 200 mm.
In order to avoid bank failures, equipment heavier than 2 tons shall not be used within 1.50 m of the slope edge.
Compaction near the facing of the wall, behind the pre-cast elements, shall be carried out manually with a vibrating plate.
In order to consolidate the bank face, a length of geogrid, as detailed in the design, shall be left outside the filling layer such that, after compaction of the layer, the geogrid can be raised and turned up the bank face and then laid on top of the layer. The length of this strip shall be equal to the thickness of the layer +1.5 m.
The geogrid for the next layer shall be laid according to the design specifications.
In order to have a grass planted facing, between the pre-cast elements (layers) seeding with grass seeds shall be executed.
After the last layer has been laid (upper level) the geogrid shall be embedded into the filling material in accordance with the design details.
2.9.2.3 Materials - Quality specifications
Pre-cast units of reinforced concrete
The pre-cast units made of reinforced concrete shall comply with the Specifications and the technical conditions according to standard STAS 6657/1-89.
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Geogrids
The material specified for embankment reinforcement is a geogrid with stress resistance in one direction or both. The characteristics and the anchoring length are specified in the design details, for each type of geogrid and each height of wall.
Each type of geogrid used shall have a certificate which shall state its strength in each direction with limited distortion and a guarantee certificate from the Manufacturer giving the terms under which these qualities are guaranteed and the time over which the guarantee is effective.
Filling material
There are two types of filling material that can be used:
Granular material with maximum clay content of 10% and with an internal angle of friction of at least 25o may be locally obtained. The material shall have a continuous grading. The maximum grain size shall be 1/3 of the thickness of the layer and shall be chemically inert;
Local soil which must fulfil the following conditions:
- shall not contain organic materials;
- shall not be of clay sensitive to water;
- shall be compacted to a normal Proctor grade of 98%.
2.9.2.4 Quality checking
The position of the pre-cast elements
Topographic measurements shall be carried out to check compliance with the design for:
The horizontal location of each element;
the vertical position of each layer.
The position of geogrids
The tolerances for the position of geogrids in the body of embankment are the following:
in the direction of maximum stress, all geogrids must be placed with a deviation of + 50 mm
vertically, the layer thickness, shall be within + 30 mm
the overlap shall be 200 mm + 50 mm
Filling using local granular material
In order to ensure a satisfactory quality of work, checking shall be carried out by survey at each stage of filling (500 mm of wall):
topographic checks including the volume laid and the gradients in accordance with the Specifications. The position of the checks shall be selected at random by the Engineer, but at least 2 for every 50 m of wall. The position of the geogrids must not deviate from those in the design by more than 100 mm in plan, and 50 mm vertically.
the checking of the degree of compaction of the soil, which shall not be less than 98% Normal Proctor.
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2.9.3 Concrete retaining walls
2.9.3.1 General data
The construction of retaining walls using cast-in-place reinforced concrete includes the following operations:
excavation and propping of the exposed faces;
construction of the foundation;
shaping and fixing of the reinforcement and formwork;
construction of the vertical wall;
installation of the drain behind the wall and backfilling.
2.9.3.2 Description of operations
Excavation and support of the exposed faces
Excavation may be either manual or mechanical and will require earth faces to be supported to avoid the possibility that instability may occur. The supports may be either of wood or metal and they shall be installed at the same time as the excavation.
When the excavation requires the uncovering of existing live underground services (water, gas, electric, etc.), appropriate measures shall be taken to protect them from damage. If such services are unknown and they are discovered during the excavation, the works shall be suspended and the service owner informed, so that the necessary measures may be put in hand.
At the completion of excavation, an inspection report shall be prepared, regarding the foundation level and the characteristic foundation soil.
The excavated earth shall be removed from the area.
Construction of the foundation
The placing of concrete into the foundation shall be carried out immediately after the completion of the excavation and its approval. The poured concrete shall adhere to the walls of the excavation. The props shall be dismantled at the same time as the concrete is poured into the excavation.
The pouring of the concrete shall be carried out without interruption in 200-500 mm thick layers up to the design level. Metal or wooden chutes shall be used according to the regulations for concrete placement, provided in the “Practice codes for the construction of concrete, reinforced concrete and pre-stressed concrete works”, indicative NE 012-99. The free fall of the concrete not be greater than 1.5 m.
Working joints shall be avoided, but where this is unavoidable, the joint shall be formed according to the “Practice codes for the construction of concrete, reinforced concrete and pre-stressed concrete works”, indicative NE 012-99.
Reinforcement of OB37 steel bars shall be provided at the foundation and the wall.
Fixing of the reinforcement
The walls and the foundations for guardrail type 2 made of reinforced concrete requires the in-situ fixing of reinforcement (bar by bar), according to the reinforcement details shown on the construction drawings.
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After fixing, the required notification and acceptance procedure shall be followed and shall be recorded in the stage report.
Construction of the vertical wall (elevation)
Depending on the wall type, the main operations are:
shuttering of the wall in accordance with the design requirements;
fixing the reinforcement;
fixing of PVC tubes type M 65 mm diameter in the weepholes to ensure the discharge of water;
pouring and vibrating concrete in the wall.
The concrete class shall be in accordance with the design.
Before the pouring of concrete into the shutters, the following items shall be checked:
the plan dimensions and the levels of the excavation;
the correct installation of the shutters to the design levels;
the vertical position of the shutters and the provision of measures to maintain their shape and ensure their water tightness;
concrete placement equipment;
the provision of concrete compacting equipment;
the clean state of shutters and reinforcement, and cleaning if necessary.
To avoid any internal stresses due to contraction and to heat dissipation, the use of concrete grades with aggregates featuring a Dmax as large as possible is recommended.
The shutters shall be stripped after the concrete has hardened sufficiently to keep its required shape. The minimum time for removal of the shutters depends on the cement type used in the concrete and on the ambient temperature.
Shutter removal shall be carried out in reverse order to the installation. Stripping shall be carried out carefully to avoid damage to the edges and surfaces of the concrete. Any defects in the concrete shall be made good.
Installation of the drain behind the wall
In order to protect the wall and the foundation for guardrail against water infiltration waterproofing consisting of two layers of bitumen emulsion shall be applied to the concrete surfaces. A drain shall be constructed behind the wall to collect water which shall be discharged through the wall via weep holes.
The drain shall be of crushed stone, gravel or ballast, in accordance with the design details.
The wall connection to the embankments and the slope finishing shall also be carried out.
2.9.3.3 Materials - Quality requirements
Water
Water for mixing concrete shall be free from materials that affect hydration of the cement.
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The water used to prepare the concrete may be taken from public supply or from other sources. The Water from all sources shall be checked for compliance with the technical requirements provided in STAS 790-84.
The water shall be tested at the beginning of the works and the tests shall be repeated whenever a change of the water characteristics is noticed.
The water to be used on the site shall be protected against contamination by detergent, organic matters, oils, clay etc.
Cement
Cement required by the recipe for the specified concrete shall be used and shall correspond to the quality conditions set down in the appropriate code.
Aggregates
For cast in-situ concrete and for the filling of the drain, ballast, sand, broken stone and gravel (corresponding to the provisions of STAS 1667/76, STAS 4606/80, STAS 662/89, SR 667/1997) shall be used.
Formwork
Standard shutters are industrially manufactured and must ensure the following:
the shapes and the sizes required by the design;
to be water tight so as not to lose the cement slurry;
to be stable and resistant to the loads that might arise during concreting;
to be erected with assembly pieces;
the parts that have contact with the concrete shall be lubricated.
Plain concrete - The quality of the concrete shall be established by the designer depending on the work conditions and its purpose. The minimum concrete classes shall be established in accordance with the “Code of Practice for the execution of concrete, reinforced concrete and pre-stressed concrete works", indicative NE 012-99.
Reinforcing steel
For reinforcement, OB 37 and PC 52 steel shall be used according to 438/1-89 STAS and to the Design Specifications.
2.9.3.4 Quality checking
Work platform
The following elements shall be checked:
the geometric shape in cross section and in plan;
construction of the road structure using the correct materials approved by the Engineer;
ensuring drainage of water from the works area during construction;
signing of the site.
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Excavation and supporting the trench sides
The following elements shall be checked:
the plan position;
the foundation sizes;
the measures taken for the protection of the works and for traffic safety;
the nature and condition of the foundation soil;
the check of the supports for the foundation;
the comparison between the site conditions and the technical requirements of the design;
a report on the buried works.
Reinforcing fixing
Details of the shape, type of steel, diameters, spacing and cover used shall be checked.
Formwork installation
When the shutter has been installed, the following elements shall be checked:
shutter supports and propping;
proper sealing of the shutter units;
the internal sizes of the shutters;
position and level of the shutters.
The foundation and the wall concreting
Checks shall be carried out on the fresh and the hardened concrete:
at the concrete plant one sample per shift and per concrete type shall taken;
the maximum period of transport depending on the temperature and quality of the concrete shall be complied with;
the temperature of the fresh concrete at placement shall be higher than 5oC;
concrete workability;
the fresh concrete quality - by taking samples;
concrete vibration;
the concrete quality shall be checked to be in accordance with the results determined at the trials by carrying out checks of the class using non-destructive tests or core tests.
Wall stripping
The following elements shall be checked:
the condition of the dismantled elements;
the wall sizes and surface finish;
the weep hole positions.
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The drain behind the wall
The following elements shall be checked:
the functioning of the weep holes;
the drain sizes;
the material quality.
These checks shall be carried out according to the Code of Practice for the “execution of concrete, reinforced concrete and pre-stressed concrete works" indicative NE 012-99 and according to Law no. 10/95 and on the basis of "Programme for the works quality control". The Designer, the Employer and the Contractor have agreed to all these checks. A report on the buried works, a report on the quality acceptance or an official report shall be completed.
2.9.4 Precast cantilevers
2.9.4.1 General data
This kind of work is necessary to provide the required carriageway width, over an existing retaining construction.
The construction of the pre-cast cantilevers consists of the following operations:
Preparation works;
Setting out of the pre-cast cantilevers.
2.9.4.2 Description of operations
Preparation works
These works consist of:
removal of the existing road pavement;
demolition of the headwall of the existing embankment retaining wall to levels shown in the design;
pouring of concrete as a bedding layer 100 mm thick.
Setting out of the pre-cast cantilevers
The setting out of the precast cantilevers consist of:
cleaning the area where the elements are to be placed;
placement of the precast cantilevers side by side, with no spaces between;
fixing the reinforcement for the monolithic slab;
pouring the concrete in the monolithic slab;
construction of the anchorage for the cantilevers according to the Technical Specifications for anchors;
waterproofing;
reinstatement of the road pavement;
installation of parapet pillars;
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road signing to prohibition parking in the area.
2.9.4.3 Materials - Quality requirements
Water
Shall be in accordance with STAS 790/84.
Cement
To prepare concrete, the cement required by the mix design for the specified concrete shall be used and shall correspond to the quality conditions set down in the appropriate code.
Aggregates
For cast in-situ concrete, ballast, sand, broken stone and gravel (corresponding to the provisions of STAS 1667/76, STAS 4606/80, STAS 662/89, SR 667/1997) shall be used.
Formwork
Standard shutters are industrially manufactured and must ensure the following:
the shapes and the sizes required by the design;
to be water tight so as not to lose the cement slurry;
to be stable and resistant to the loads that might arise during concreting;
to be erected with assembly pieces;
the parts that have contact with the concrete shall be lubricated.
Plain concrete - The quality of the concrete used shall be established by the designer depending on the work conditions and its purpose. The minimum concrete classes shall be established in accordance with the Code of Practice for the execution of concrete, reinforced concrete and pre-stressed concrete works", indicative NE 012-99.
Reinforcing steel
For reinforcement, OB 37 and PC 52 steel shall be used according to 438/1-89 STAS and to the design specifications.
2.9.4.4 Quality checking
Work platform
The following elements shall be checked:
the geometric shape in cross section and in plan;
ensuring drainage of water from the works during construction;
signing of the site.
Precast cantilever
Checks of the precast units shall be carried out according to STAS 6657/1-89.
Reinforcement fixing
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Details of the shape, type of steel, diameters, spacing and cover shall be checked.
Formwork installation
When the shutter has been installed, the following elements shall be checked:
shutter supports and propping;
proper sealing of the shutter units;
the internal sizes of the shutters;
the position and level of the shutters.
Monolithic beam concreting
Checks shall be carried out on the fresh and the hardened concrete:
at the concrete plant one sample per shift and per concrete type shall taken;
the maximum period of transport depending on the temperature and quality of the concrete shall be complied with;
the temperature of the fresh concrete at placement shall be higher than 5oC;
concrete workability;
the fresh concrete quality - by taking samples;
concrete vibration;
the concrete quality shall be checked to be in accordance with the results determined at the trials by carrying out checks of the class using non-destructive tests or core tests.
These checks shall be carried out according to the Code of Practice for the “execution of concrete, reinforced concrete and pre-stressed concrete works" indicative NE 012-99 and according to Law no. 10/95 and on the basis of "Programme for the works quality control". A report on the buried works, a report on the quality acceptance or an official report shall be completed.
2.9.5 Anchors
2.9.5.1 General data
Two types of anchors are used:
multithread anchors – used for anchoring existing retaining and embankment concrete walls;
anchors made of one steel bar – used for anchoring the concrete cantilevers.
The installation of anchors shall be carried out as follows:
drilling of the boreholes;
insertion of the anchors into the boreholes;
injection of the boreholes;
tensioning the multithread anchors;
quality checking.
2.9.5.2 Description of operations
Multithread anchors
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This type of anchor shall be of steel type SBP 7 mm diameter, necessary for anchoring the existing retaining walls.
The main components of the anchors are:
SBP wire 7 mm diameter;
corrugated tube (without holes) made of PVC in the area of the anchoring bulb;
smooth tube of PVC for protection of the free length of the anchor;
spacers for arrangement of the wires in the anchor, placed every 800 mm along the length of the anchor wire;
steel straps for gathering the wires between the spacers;
locking wedges made of concrete to maintain tension of the wires;
injection pipes – interior and exterior pipes;
aerating pipes;
bridle made of 7 mm diameter wire – with a role of interior spacers;
exterior spacers made of PVC at 1.200 mm;
anchoring head trumpet type;
blocking cones;
protection cover.
The dimensions of the anchors shall be according to the design drawings.
Anchors made of one steel bar
This type of anchor shall be of one steel bar PC52, 30 mm in diameter
Drilling of the boreholes
The boreholes for the anchors shall be drilled at the angles marked on the drawing.
The diameter of the boreholes is a minimum of 146 mm.
The boreholes shall be drilled in the dry and a tube shall inserted as drilling progresses to prevent collapse of the borehole.
The borehole lengths shall be in accordance with the design details. The provided length shall be 20 m and 30 m, measured from anchorage plates.
Insertion of the anchors into the boreholes
After the drilling of the boreholes the anchors shall be inserted into the boreholes. A crane equipped with a retractable beam and a hinged scaffold are necessary for this operation. The scaffold shall be set at the correct angle for each anchor.
This operation should be carried out with caution because of the long length and heavy weight of the anchors. Care should be taken to ensure that the PVC protection tube is not damaged.
To facilitate the movement of the anchor inside the borehole, spacers on the exterior of the anchor should be of plastic, wedge type, fixed at each 1.20 m.
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If the protection tube is slightly damaged, it shall be repaired with glue and bandaged with PVC adhesive tape. Care should be taken not to block the tube sections. If the tube is seriously damaged (sheared, broken, etc.), it shall be replaced.
Injection of the boreholes
Each anchor shall be injected with cement grout with 500 kg cement/m3 and a variable water/cement ratio which is a function of the injection position (internal or external).
Injection of boreholes for the multithread anchors
The steps for this operation are as follows:
Internal injection of the anchorage bulb with cement grout through the inner PVC tube of 15 mm diameter until the cement grout is draining without carrying air bubbles through the outlet of the airing tube (PVC tube of 10 mm diameter);
External injection of the anchor along the whole borehole length through the PVC tube of 15 mm diameter mounted on the anchor protection tube. The external injection is completed when the cement grout appears from the borehole;
Injection of the free length of the anchor is carried out after the anchor has been tensioned (minimum 14 days from the external injection).
Injection of the boreholes for the steel bar anchors
The injection of the boreholes for the steel bar anchors shall be carried out uniformly along the whole length of the bar in a similar manner to the first two steps in section VII.2.6.
Tensioning of the (multithread) anchors
The steps of this operation are as follows:
A trial anchor is pulled at a constant force of 120 tf for two minutes and if there is no slipping of the anchor it is then blocked at 80 tf;
The rest of the anchors are tensioned with a force of 100 tf and blocked at 80 tf;
After the tensioning and blocking of the anchors, the free length of the anchors can be injected.
2.9.5.3 Quality checking
Checks shall be carried out as follows:
Quality checking of the component materials of the anchor;
Quality checking of the component materials used for the injection fluid;
Quality checking of the assembled anchors;
Continual checking of the preparation of the injection fluid (mixing ratio and consistency);
Checking of the completeness of the fill of the borehole and of the anchor bulb during the injections by continually monitoring according to section VII.2.6.
2.9.6 Drilled pile retaining walls
2.9.6.1 General
The main uses of drilled columns with reinforcement (Benotto type) of 1080mm diameter are:
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retaining walls of drilled columns arranged in a single row;
retaining walls of drilled columns arranged on two or more rows, working as a frame.
The construction phases mentioned below present particularities according to the adopted solution:
construction of the working platform;
drilling for the columns;
reinforcement of the column;
pouring concrete into the column;
excavation for the raft construction;
reinforcement of the concrete raft;
pouring concrete into the raft.
2.9.6.2 Description of operations
Working platform
The working platform is the carriageway.
Drilling of Columns
The Benotto type columns with reusable tubes are constructed as follows:
setting out of the row of columns to be constructed first and setting out the marking points with levels and positions;
setting up machinery and drilling;
installing the tubes;
excavating soil from the tubes until the level of the column required by the design details is reached.
Column construction shall start with the row that has the greatest number of columns and if there are multiple rows with the same number of columns, construction shall start with the row furthest downstream.
Reinforcement of the columns
Reinforcement of the Benotto type columns shall be made of circular cages and consists of:
construction of reinforcement cages and their transport to the working site;
placement of the reinforcement cage into the hole using a crane.
If the reinforcement cage is made in sections, the sections shall be joined progressively as they are inserted into the tubes.
The bottom of the reinforcement cages shall be provided with a round steel plate half of the diameter of the column.
Concrete pouring of the columns
The method of concrete pouring depends on the presence or absence of water in the drilled hole. There are two kinds of techniques which are the most commonly used:
under water;
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in dry conditions.
Both techniques consist of the following operations:
C20/25 concrete pouring into columns with:
- in dry conditions – a workability of the concrete of L4 (100 – 150 mm) degree for concrete pumped by the hydraulic pump with a 20 m3/hour plunger;
- under water – a workability of the concrete of L4/L5 (150 – 180 mm) degree for the concrete poured by free falling using pipes.
removal of the tubes shall be progressive as the level of the placed concrete rises.
For concrete pouring in dry conditions, the bottom of the concrete delivery pipes shall not be more than 1.50 m above from the surface of the poured concrete.
For concrete pouring under water conducting pipes with a minimum diameter of 200 mm shall be used; the concrete shall be poured continuously at a minimum rate of 4 m 3/hour. The depth of the delivery pipe shall be 2 – 3 m below the level of the poured concrete surface. The base of the tubes shall be at least 2 m below the level of the poured concrete surface.
The material that does not fulfil the quality conditions shall be removed.
The top of the column shall be finished at a level of:
+ 0.50 m above the design level for columns constructed in dry conditions;
+ 1.00 m above the design level for columns constructed under water.
After the completion of the columns and before construction of the concrete raft, the top of the columns shall be demolished down to the design level, but reinforcement will be retained.
Reinforcement of the concrete raft
Reinforcement of the concrete raft shall be by OB37 steel bars, unless otherwise shown on the drawings.
Concrete pouring for the raft and walls
Concrete pouring into the raft and walls shall be carried out directly from the delivery vehicles by means of a metallic or wooden chute, so that the concrete falls free from a height of less than 1.50 m. The concrete shall be vibrated.
The walls shall be constructed as follows:
shutter erection;
fixing of reinforcing;
PVC tube placement for weep holes;
concrete pouring and vibration;
drain construction.
2.9.6.3 Materials – quality conditions
Water
Shall be in accordance with STAS 790/84.
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Cement
The cement required by the mix formula for the specified concrete shall be used and shall correspond to the quality conditions set down in the appropriate code.
Concrete
The quality of the concrete to be used shall be established by the designer depending on the work conditions and its purpose. The minimum concrete classes shall be in accordance with the “Code of Practice for the execution of concrete, reinforced concrete and pre-stressed concrete works", indicative NE 012-99.
The concrete that is used for column construction shall have a fluid consistency and composition according to the following:
in dry conditions – a minimum quantity of 350 kg/m3 and workability at the working site of L4 – for pumped concrete (8 - 10 m3/hour);
under water – a minimum quantity of 400 kg/m3 and workability at the working site of L4/L5 for the concrete poured by means of pipes (min. 4 m3/hour)
The maximum aggregate dimension shall be at most equal to the lower of the following values:
¼ of the cage grid dimension;
½ of the concrete cover over the reinforcement;
¼ of the interior diameter of the column;
31 mm.
The water – cement ratio shall be in conformity with the drawings.
Additives may be used, or, if necessary, quick setting or retarding materials if approved by the Engineer.
The concrete cover for the reinforcement shall be at least 60 mm.
The permitted deviations from the design are:
for the plan layout of the columns, at the raft level:
- 75 mm for the columns in a single row;
- 100 mm for the columns in multiple rows;
2% from the total length for the horizontal deviation of the column axis from the vertical;
20 mm for the column diameter;
for the levels:
- 200 mm at the bottom of the column;
- 50 mm at the head of the column.
Concrete class poured in the raft shall be in conformity with the design, its workability at the working site shall be L3 and it shall be vibrated once cast in place.
The minimum concrete cover to the reinforcement shall be 50 mm.
The Constructor shall establish the workability of the fresh concrete at the concrete plant to take into account the environmental conditions and the total transportation time before placement.
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Aggregates
For cast in-situ concrete and for filling of the drain, ballast, sand, broken stone and gravel (corresponding to the provisions of STAS 1667/76, STAS 4606/80, STAS 662/89, SR 667/1997) shall be used.
Reinforcement steel
For column reinforcement two types of used steel are used:
OB 37 – as per STAS 431/1-89;
PC 52 – as per STAS 431/1-89.
For the resistant reinforcement of a column, only one type of steel shall be used – PC52 or OB37; the two types of steel shall not be mixed.
For the concrete raft, OB 37 steel shall be used.
2.9.6.4 Quality check
For proper execution of the works, quality checking shall be performed at various construction phases:
Construction of the working platform
The platform shall be checked constantly by visual means or, if necessary, by surveys.
Quality checks of the ballast (STAS 662 – 89) shall be performed on batches of the same aggregates and dimensions, max 200 t / batch, by the method of “batch checking” regarding:
Granularity;
micro-granules or organic materials;
the degree of compaction of the platform.
Drilling of the column hole
At this stage, the following shall be checked:
the nature of the soil (for comparison to the soil characteristics considered at the design stage);
level and depth of the hole;
the horizontal deviation from the vertical axis of the tubes shall not exceed more than 2% from that required in the design details.
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Reinforcement of the column
At this stage, the following checks shall be carried out:
check of the reinforcement cage according to the design details (to ensure a rigidity for transport and manipulation);
check of the reinforcement bars according to the design details;
check of the proper installation of the cage sections so that the reinforcement cage can be properly centred and concrete cover is obtained;
if the reinforcement cage snags while putting it into the hole, it shall be immediately extracted, verified and cleaned, and the operation shall be performed again.
Concrete pouring into the column
The quality check of the concrete shall be performed “during the pouring” and “after finishing” the column as follows:
Checks “during pouring”:
concrete pouring shall be carried out immediately after the placement of the reinforcement cage and shall be continuous;
pouring breaks of more than 2 hours shall be avoided;
the upper level of the column shall be checked;
the temperature of the concrete during placing shall be more than 5 C;
quality check of the fresh concrete by sampling as follows:
at the concrete plant: 3 samples for each 20 m3 of concrete;
at the work site:
- 1 sample for each concrete type and work shift;
- check of the drilling / concrete pouring document produced by the Contractor
checks “after the execution”:
the quality control of the in-situ concrete;
checks of the continuity of the column:
for columns that show deficiencies during the drilling and concrete pouring phases;
to a certain number of columns established by the design details.
These checks shall be performed by specialised institutions using sonic methods.
Reinforcement of the concrete raft
After the placement of the reinforcement for the raft and before the start of concrete pouring, the following checks shall be carried out:
the reinforcement is not to be dirty, greasy or rusty;
the reinforcement bars should be the same as designed;
the concrete cover shall be according to the design details;
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the reinforcement for the walls shall be placed in the correct position.
Concreting of the raft and wall
Checks shall be carried out before, during and after the finish of the concrete pouring, as follows:
position of the concrete pouring area;
shuttering layout, dimensions and levels;
concrete shall be poured continuously with no interruptions;
if pouring by stages, each stage shall be executed before hardening of the concrete already poured. If not, the construction joint shall be treated as follows:
- the surface of the concrete shall be cleaned;
- pouring the next layer of concrete;
curing of the concrete by using protection materials (tarpaulin or mat) which shall be kept wet;
spreading water on the hard concrete surface if the temperature is above 5 C;
covering of the fresh concrete with plastic if raining.
2.9.7 Drainage using drilled columns filled with ballast
2.9.7.1 General
The construction phases mentioned below vary according to the adopted solution:
construction of the working platform;
drilling for the columns;
ballast filling;
cover of the drain.
The columns shall be constructed overlapping each other with an inter-penetration of 150 mm.
2.9.7.2 Description of operations
Working platform
The working platform is the carriageway.
The ballast layer shall be constructed after site clearance the removal of topsoil in the area.
Drilling of Columns
The Benotto type columns with re-usable tubes shall be constructed as follows:
setting out of the row of columns to be constructed first and setting out the marking points with levels and positions;
setting up machinery and drilling;
installing the tubes;
excavating soil from the tubes until the level of the column required by the design details is reached.
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Ballast filling
After the borehole is complete, the ballast shall be laid and compacted in layers of 300 – 400 mm. The tubes shall start to be withdrawn when 1.50 m of ballast has been laid. The bottom of the tube shall be kept at a minimum of 0.5 m below the top of the ballast as it is placed.
The cover of the drain
The cover of the drain is the gutter.
2.9.7.3 Materials – quality conditions
Ballast
For filling, ballast corresponding to the provisions of STAS 1667/76, STAS 4606/80, STAS 662/89, SR 667/1997 shall be used.
2.9.7.4 Quality check
During construction, quality checks shall be carried out as follows:
Construction of the working platform
The platform shall be checked constantly by visual means or, if necessary, by surveys;
Quality checks of the ballast (STAS 662 – 89) shall be performed on batches of the same aggregates and dimensions, max 200 t / batch, by the method of “batch checking” regarding:
-Granularity;
-micro-granules or organic materials;
- the degree of compaction of the platform.
Drilling of the columns hole
At this stage, the following shall be checked:
level and depth of the hole;
the vertical inclination of the tubes shall not deviate by more than 2% from the inclination required by the design;
the distance between the centre lines of two successive columns shall be between 900 and 950 mm.
2.9.8 Sub soil drainage
2.9.8.1 General data
Drainage are works necessary for:
the collection and disposal of water seeping via the ground;
lowering the level of the water table when this can affect the behavior of the road or of other works;
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the consolidation of slopes, earthworks etc., which can affect the road platform or other works;
the improvement of the conditions of service and to ensure the stability of retaining walls and abutments of bridges and underpasses.
The following construction activities shall be carried out:
excavation;
laying of the drain (bed, drain pipe, air shafts, geotextile material);
construction of inspection chambers.
2.9.8.2 Description of operations
Excavation
Excavation shall be carried out by machine or by hand from downstream to upstream.
The longitudinal gradient of drains with flexible bedding will depend upon the topography but will be between 0.2% and the maximum gradient permitted for protected ditches and channels stated in STAS 2916-87 paragraph 22.
Before starting the works, the following measures shall be taken:
delineating the working area in accordance with the current regulations;
ensuring the dispersal of rainwater from the site;
removal of any materials (rock, stones) in danger of falling from the slopes or sides, onto the working area or onto the platform;
identifying the existing overhead or underground services, and the respective owners in order to establish the conditions required for the safe performance of the work;
setting out;
the organisation and the supply to the site of at least 50% of the necessary materials.
During excavation, the following aspects shall be taken into account:
the safety of the existing structures and installations, visible or buried, as well as works under progress in the vicinity;
speed restriction on the site of in the vicinity of trenches to ensure safe works condition;
daily, before work starts and at its end, the timbering and the state of the ground around the excavation shall be checked, in order to take any measures necessary to avoid possible landslips and danger of accidents.
Excavation shall be carried out with vertical faces without linings, by hand or machine, in the following situations:
the ground is stable and with natural moisture content;
the ground has no cracks and it is not subject to vibration;
the excavation is not kept open and filling is carried out the same day;
there is no traffic and no structures, deposits or overburden within the limit of a possible failure prism;
the depth of the excavation is relative small.
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In ground, affected by instability, difficult soils (loess, shrinking clay, etc) loose soils, earth with water infiltration or special local conditions, for any depth, timbering shall be used with frames and poling boards (possibly driven poling boards or sheetpiling) which shall make a continuous and tight wall. The poling boards or the sheet-piles shall be driven down (0.5...0.75 m) beneath the level of the base of excavation.
In areas with buried cables, pipes or archeological sites, excavation shall be carried out carefully observing the written instructions given by the offices managing those installations, possibly under the supervision of a delegate from this office.
If during excavation, underground services are found, the works shall immediately be stopped and when they are identified the respective owner shall be notified. The works may be resumed only after having eliminated any danger and under supervision of a delegate of the office owning the service.
Excavations for drains shall be carried out from downstream to upstream, to ensure a constant free flow of water from the excavation.
Excavation of the next section may be started when the first section has been filled for at least half the depth.
Removal of the lining shall be carried out in step with the filling.
For machine excavations, the excavation and filling shall be carried out successively so that no open excavation remains at the end of a working day. As a rule, this method shall be applied to drainage trenches fitted with corrugated and perforated drainage pipes surrounded by gravel or ballast with a filter membrane of geotextile.
Installation of drains
Drains for collecting the groundwater infiltration or for lowering the level of the ground water table, consist of: bed, channel, drain filling and cover. Discharge drains include the same components.
Flexible bedding shall be constructed by compacting the base ground.
Geotextile shall be then installed on the base and sides of the trench. Corrugated and perforated pipes of PVC are laid directly on the base of the excavation on the geotextile
The filling shall be ballast placed in layers 300 – 400 mm thick and compacted.
Geotextile filter membrane shall be installed so that the strips overlap by 100 mm, so that the soil does not penetrate into the body of the drain. It is recommended that the strips be sealed mechanically. In this case the overlap may be only (20 - 30 mm). Overlapping at the top shall be 200 - 300 mm.
The cover of the drain is either:
the road ditch for longitudinal drains;
the road pavement for transverse drains.
Inspection chambers
In order to control the operation and to enable maintenance to be carried out, "inspection chambers" at 50 m centres shall be provided. Inspection chambers shall also be located at changes of direction and at the intersection of two or more drains.
At the upper end inspection chambers shall be provided with holes for natural ventilation.
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In the inspection chamber, the invert of the upstream drain pipe shall be at least 100 mm higher than the invert of the downstream pipe.
The head of the drain
It is constructed when the drain cannot be connected to culverts.
The head of drain shall be made with a facing of rubble stone or of river stone on a bed of plain concrete in accordance with the design.
2.9.8.3 Materials to be used - quality requirements
Granular materials (ballast or gravel)
For drain filling, granular material with no micro-granules or organic materials (ballast type 0 to 7 mm or gravel type 7 to 40 mm as per STAS 662-89) with continuous grading shall be used.
Rubble stone
Rubble stone shall be used for facing the closing cover of the drains or for the masonry of the drain head in accordance with STAS 2917-79.
Geotextiles
For geotextile filters, materials with the specified characteristics on the drawings shall be used. The type of the geotextile shall be proposed by the Contractor and approved by the Engineer.
Drain pipes
Perforated, corrugated pipes (NI 8500-80), made of PVC or polyethylene with diameters of (65 to 120 mm), used for collector drains, shall be laid according to the drawing details directly onto the bedding and shall be protected with drain filling of ballast or gravel.
Ingress of water into the pipes shall be through slots 1.0 x 5.0 mm or 1.5 x 8 mm, in such a number as to achieve an active surface of (24 to 50 cm2) per linear metre of pipe.
Smooth, unperforated pipes of PVC in accordance with STAS 6675/2-92, with a diameter of 90 to 110 mm shall be used for conducting water to the discharge drains and for connection to the inspection chambers.
Plain concrete
Concrete class for the construction of the inspection chamber rafts shall be used in conformity with the drawings.
Pre-cast concrete rings
Pre-cast concrete rings with a diameter of 1000 mm, in accordance with STAS 816-80 shall be used for the construction of the inspection chambers.
Steel
Access steps in the inspection chambers and the reinforcement of the inspection chamber cover, steel OB 37 in accordance with STAS 438/1-89 shall be used.
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2.9.8.4 Quality control
In order that appropriate methods of working are followed, inspections shall be carried out at all stages of construction as follows:
Excavation
At this stage, the quality control shall consist of:
checking the location of the works;
the acceptance of the foundation ground of the bed;
checking of the underground water level;
checking of the dimensions and of the slope of the foundation ground;
the inspection of the timbering when they are required by the design;
checking of the length of the section of excavation.
The installation of the drain
For this phase, the quality control shall consist of:
checking of the gradient and of the cross fall of the bed invert;
checking of the geotextile used which consists of:
- identifying the product by examination of the labels fixed to the bales;
- determination of the unit mass;
- checking the storage and handling conditions;
- inspection of the geotextile arrangement so that the continuity (overlapping or seaming) is ensured;
- protection of the geotextiles from wind action;
- restrictions of traffic on the geotextile;
- checking that damage to the geotextile is not caused by the placement of filling materials.
the inspection of the type and of the dimensions of the drainage pipe and its laying on the bed;
inspection of the ballast or gravel on batches of the same type and different types of aggregate for every 200 t:
- checking the grading;
- the conditions of inverted filter;
- foreign matter;
- fines content.
The construction of the drain head
Inspection of the operation of drains by checking the flow during a period of 5 to 10 days. If the flow is approximately constant, it indicates that the drain has entered into a continuous operating regime.
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If the flow continuously decreases, the drain might be silted up, or might be losing the collected water, or the water in the ground may have dried up.
The construction of the inspection chambers
At this stage, the quality control consists of:
the verification that the upstream drainage pipe which has been installed at least 100 mm above the level of the downstream drainage pipe;
visual inspection of the step irons, concrete joints, cover slab, etc.
checking the operation of the upstream drain.
2.9.8.5 Gabions and Rockfill Mattresses
Gabions and rock filled mattresses shall be as indicated on the drawings and be fabricated on site.
Rock fill shall be appropriate to suit the mesh size and be to the approval of the Engineer.
2.9.8.6 Anchored Wire Nets
Slope protection with anchored wire nets shall be carried out on the finished slope surface and consists of the following operations:
transportation of the wire net to the top of the slope;
fixing of the wire net at the top of the slope using anchors of reinforcing steel grouted in with an approved cement mortar grout;
wire net shall be laid down the slope;
further anchoring of the wire net on the slope by steel pegs driven into cracks in the rock or by other approved methods such as drilling and grouting;
top soil of 20 – 30 mm thickness shall be laid in pockets where indicated;
planting of pockets as described on the drawings or in the scope of the works;
care of the plants until they are established.
Anchoring arrangements shall be to the satisfaction of the Engineer.
Details of wire nets shall be as indicated on the drawings and be fabricated on site.
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