specification for base & surface courses

7/29/2019 Specification for Base & Surface Courses

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Base and Surface Courses (Bituminous) Section 500

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501. PREPARATION OF SURFACE

501.1. Scope

This work shall consist of preparing an existing granular or blacktopped surface to

specified lines, grades and cross-sections in advance of laying a bituminous course. The

work shall be performed on such widths and lengths as shown in applicable drawing andconsist of scarifying and re-laying the granular base course and/or scarifying the existingsurface, filling of potholes, sealing of cracks and/or application of a profile corrective

course (leveling course) as necessary.

501.2. Materials

501.2.1. For scarifying and re-laying the granular surface : The materials used shallbe coarse aggregates salvaged from scarification of the existing granular base course

supplemented by fresh coarse aggregates and screenings so that aggregates andscreenings thus supplemented correspond to Clause 404: Water Bound Macadam or

Clause 406: Wet Mix Macadam, as the case may be.

501.2.2. For patching potholes and sealing cracks: For patching potholes,approved material having same specification as that of profile corrective course shall be

used. For sealing small cracks finer than 3 mm, a fog seal conforming to Section 3000shall be applied while larger cracks wider than 3 mm shall be treated with an emulsion

slurry seal, conforming to Clause 516.

501.2.3. For profile corrective course: A profile corrective course (levelingcourse) is essentially a pavement base material course for correcting the existing

pavement profile which has either lost its shape or has to be given a new shape to meet

the requirement of specified lines, grades and cross-sections.

It shall be differentiated from the strengthening course or other type of structural

pavement course needed for upgrading as a remedial measure against inherently deficientand/or distressed pavement. It is meant to remove the irregularity in the existing road

profile only.

501.2.4. Profile corrective course and its application: The type of material forprofile corrective course shall be as shown on the drawing. If it is to be laid as part of the

overlay/strengthening course, the profile corrective course material shall be of the samespecification as that of the overlay/strengthening course. However, if provided as a

separated layer, it may be of the same specification as the layer over which it is to be laidor intermediate between underlying and overlying layers, as shown on the Drawing.

(i) Wherever isolated high spots projecting over the pavement surface do exist, the same shall becut by milling machine or any other approved method, to minimise the profile corrective

course requirement. If, in the process, the bottom layer gets disturbed, the local area shall becut and filled with profile corrective course material.

(ii) Where the maximum profile corrective course thickness works out to be not more than 40mm, it shall be done as an integral part of the overlay course. In other cases, the profile

corrective course shall be provided as a separate layer adopting such construction procedures


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and using such equipment as may be appropriate to the specified type of material and

thickness of the course to be provided.

501.3. Construction Operations

501.3.1. Preparing existing granular surface: Where the existing surface is

granular, all loose and disintegrated materials shall be removed and the surface lightlywatered if the profile corrective course to be provided as a separate layer is also granular.

If, however, over the existing granular surface, a profile corrective course of bituminousmaterial is to be laid, the existing granular surface shall be primed as per Clause 502.

501.3.2. Scarifying existing bituminous surface: Where necessary, the existing

bituminous layer in the specified width shall be removed with care without causing unduedisturbance to the underlying layer by suitable method approved by the Engineer. After

removing it, all loose and disintegrated materials of underlying layer which might havebeen disturbed in the process of removal shall, before laying of the overlay course, be

reset properly by spreading/hand packing of aggregates and compacting with suitable

roller/heavy hand rammers/approved mechanical tamper so that the level of the topsurface of such scarified area shall be even and properly graded with respect to adjoiningsurface. Where applicable, the granular surface, after removal of the existing bituminous

layer, shall be primed as per Clause 502 to receive a bituminous profile corrective course.Reusable materials shall be stacked as directed by the Engineer with all lift and lead of

1000 m.

501.3.3. Patching of potholes and sealing of cracks: Before providing profilecorrective course on the existing pavement, potholes, if any, shall be drained of water, cut

to regular shape with sides vertical upto the affected depth and slightly beyond the limitsof affected area and dried. All loose and disintegrated materials from it shall be removed.

The potholes shall then be filled with material as per Clause No. 501.2.2. in layers notexceeding 75 mm after painting the sides and bottom with a thin layer of hot straight-run

bitumen/emulsion and each layer shall be compacted with approved mechanicaltampers/small vibratory roller and the top layer shall be flush with the existing

bituminous surface. All loose and/or surplus materials on the surface after making goodthe potholes, shall be removed.

The cracks in the old pavement surface shall be sealed with a fog seal if cracks aresmall (less than 3 mm width); fog seal shall consist of a spray of a bituminous cutback or

a slow-setting bitumen emulsion diluted with an equal amount of water, the rate of spraybeing 0.5 to 1.0 litre/sq.m depending upon the texture and dryness of the existing

bituminous surface. The spray is allowed to set to a firm condition and traffic is allowedonly thereafter so as to ensure that the material is not picked up by traffic. For large

cracks, the sealing shall be done with emulsion slurry seal as per Clause 516 of theseSpecifications.


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501.3.4. Laying the profile corrective course

501.3.4.1. After preparing the granular surface as in Clauses 501.3.1 and 501.3.2,

the profile corrective course with material as per Clause 501.2.3/501.2.4 shall be laid andcompacted to the requirement of particular Specification clause. Where a bituminous

profile corrective course is to be lad over a primed granular surface, a tack coat

conforming to Clause 503 shall be applied prior to laying profile corrective course.

501.3.4.2. An existing bituminous surface shall be prepared as per Clause 501.3.3.

and after applying a tack coat conforming to Clause 503, the bituminous profilecorrective course shall be laid and compacted to the requirement of particular

Specification clause.

501.3.5. In specific situation of short sags or depressions in the pavement, it maybecome necessary to provide corrective course in the form of flat wedges. Normally,

layers in maximum thickness at any point more than 100 mm shall not be provided. Inplacing multiple lifts, the lift of shortest length (at the lowest portion of the

sag/depression) should be provided first, with successive lifts extending over and fullycovering underneath layer, precluding development of a series of joints on the top

surfaces, as illustrated in Fig.500-1.

For camber correction or correction of superelevation of the existing carriageway,method as shown in the illustrative Fig.500-2 shall be adopted depending on the profile

of the existing carriageway.

501.3.6. Covering the profile corrective course: Work of Profile CorrectiveCourse shall be so planned that it shall be covered by the designed base/wearing course at

the earliest, before opening to regular traffic.

501.4. Surface Finish and Quality Control of Work

Relevant provisions of Section 900 shall be exercised by the Engineer.

501.5. Arrangement for Traffic

During the construction operations, arrangement of traffic shall be done to Clause112.

501.6. Measurements for Payment

501.6.1. The work of filling potholes shall be considered incidental to the

construction of Profile Corrective Course/bituminous course for which the existingpavement surface is prepared.

The work of filling cracks by applying fog seal or emulsion slurry seal shall be

measured in square metres, and paid separately.

501.6.2. Scarifying existing bituminous surface shall be measured in square metre.


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501.6.3. Profile Corrective Course shall be measured as volume compacted in

position in cubic metres or in tonnage as specified in the contract. The volume shall beworked out by plotting the exact profile of Profile Corrective Course as built up at site

and superimposed on the existing pavement profile.

501.7. Rates

501.7.1. Contract unit rate for scarifying of existing bituminous surface includingrepairing/resetting disturbed underlying layer and also removing and stacking

reusable/unusable materials shall include cost of all labour, supply of materials neededfor repair/resetting, hire charges of tools and plant and transportation of scarified

materials with all lifts and upto a lead of 1000 m.

501.7.2. The contract unit rate for Profile Corrective Course shall be payment in fullfor carrying out the required operations including full compensation for:

i) Making arrangements for traffic to Clause 112;ii) Providing all materials to be incorporated in the work including any royalties, fees, rents

(when applicable) and all leads and lifts, unless the contract specifically excludes any itemof material required for the work or provides for separate payment in accordance withClause 514;

iii) Preparation of the exposed surface/existing surface including filling of pot holes, allcleaning operations and application of tack coat;

iv) All labour, tools, equipment and incidentals necessary to complete the work to theSpecifications; and

v) Carrying out the work in part widths of road where directed by the Engineer.

501.7.3. The contract unit rate for sealing cracks by applying fog seal shall beinclusive of providing all materials and tools and plant and carrying out the work. The

contract unit rate for sealing cracks by providing emulsion slurry seal shall be as set forthin Clause 516.9.

502. PRIME COAT OVER GRANULAR BASE

502.1. Scope

This work shall consist of application of single coat of low viscosity liquidbituminous material to an absorbent granular surface preparatory to any superimposed

bituminous treatment or construction.

502.2. Materials502.2.1. The choice of a bituminous primer shall depend upon the porosity

characteristics of the surface to be primed as classified in IRC: 16. These are :


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(i) Surface of low porosity; such as wet mix macadam and water bound macadam,(ii) Surface of medium porosity; such as cement stabilized soil base,(iii) Surface of high porosity; such as a gravel base.502.2.2. The different ranges of viscosity requirements for the primers to be used

for the different types of surfaces to e primed, as classified in 502.2.1, are given in Table

500-1.

TABLE 500-1. VISOSITY REQUIREMENT AND QUANTITY OF

BITUMINOUS PRIMER

Type of surface

Kinematic Viscosity of

Primer at 600C

(Centistokes)

Quantity per

10 sq.m(kg)

Low porosity 30 - 60 6 to 9

Medium porosity 70 - 140 9 to 12

High porosity 250 - 500 12 to 15

502.2.3. The bituminous primer shall be Medium Curing Cutback (MC) produced

by fluxing, in an approved manner, bitumen of 80/100 penetration grade with kerosene.The cutback shall be free from water and shall not show any signs of separation prior to

use. Slow setting Cationic emulsion as per IS: 8887 may also be used, but the particulargrade to be used for the work shall be got approved by the Engineer. Sampling and

testing of bituminous primer shall be as per IS: 217, IS: 454 and IS: 8887.

502.3. Weather and Seasonal Limitations

The bituminous primer shall not be applied on a wet surface or during dust storm orwhen the weather is foggy, rainy or windy. The prime coat for surface treatment should

not be applied when the temperature in the shade is less than 100C.

502.4Construction

502.4.1. Equipment: The primer distributor shall be pneumatic tyred self-propelledpressure distributor equipped for spraying the material uniformly at the specified rates

and temperatures. Spraying by manual methods may be allowed for small areas at thediscretion of the Engineer. Power broom and/or blowers may be supplemented by hand

brooms as directed by the Engineer.

502.4.2. Preparation of road surface: The surface to be primed shall be sweptclean, free from dust and shall be dry. It shall be shaped to the specified grades and

section. It shall also be free from ruts, any other irregularities and segregated materials.Minor depressions and potholes may be ignored until the surface is primed, after which

they shall be patched with a suitable premix material prior to the surface treatment.


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502.4.3. Application of bituminous primer: The bituminous primer shall be

sprayed / distributed uniformly over the dry surface, prepared as per Clause 502.4.2 usingself-propelled sprayer equipped with self-heating arrangement, suitable pump, adequate

capacity compressor and spraying bar with nozzles having constant volume or pressuresystem capable of supplying primer at specified rates and temperature so as to provide a

uniformly unbroken spread of primer. If the surface to be primed is so dry or dusty as to

cause freckling of bituminous material, it shall be lightly and uniformly sprinkled withwater immediately prior to priming; however, the bituminous material shall not beapplied till such time as no surface water is visible. The primer shall be applied at the rate

as specified in Table 500-1.

Temperature of application of a primer need only be high enough to permit theprimer to be effectively sprayed through the jets of the spray bar and to cover the granular

base surface uniformly in the desired quantity.

The desirable range of temperatures at the time of application of MC-30, MC-70and MC-250 grades shall be 30 to 55

0C; 50 to 80

0C and 75 to 100

0C respectively. For a

bituminous emulsion primer, the range of spraying temperature may be 20 to 600

C.

Following the application of bituminous material, the surface shall be allowed tocure for at least 24 hours or for any other period so as to allow penetration into the base

course and aeration of volatiles from the primer material. If it is not absorbed within 24hours after application, sand shall be spread over the surface to blot the excess primer.

Care shall be taken to prevent over-priming; any pools of excess primer left on any partof the surface shall be swept out over the adjacent surface before spreading sand.

The primer coat shall be applied only on the topmost water bound macadam or any

granular layer, over which the bituminous base course/wearing course is to be laid.

502.4.4. Curing of primer and opening to traffic: It shall always be ensured thatwhile opening to any kind of traffic, the primed surface is fully cured and is not sticky to

avoid being picked up by traffic. Normally, the primed surface shall be allowed to curefor not less than 24 hours and during this period no traffic of any kind shall be permitted.

502.4.5. Laying of bituminous course over primed surface: Bituminous base

course or wearing course shall be laid over the primed water bound macadam, wet mixmacadam or any other granular base course, in the usual manner as per relevant

Specification for the same including the requirement of tack coat as per Clause 503.

502.5. Quality Control of Work

Control on the quality of materials and work shall be exercised by the Engineer inaccordance with Section 900.

502.6. Arrangement for Traffic

During the construction operations, arrangement of traffic shall be done as per

Clause 112.


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Prime coat shall be measured in terms of surface area of application in square

metres.

502.8. Rate

The contract unit rate for prime coat shall be payment in full for carrying out therequired operations including full compensation for all components listed in Clause 401.8

(i) to (v) and as applicable to the work specified in these Specifications.

503. TACK COAT

503.1. Scope

This work shall consist of application of single coat of low viscosity liquid

bituminous material to an existing road surface preparatory to another bituminousconstruction over it.

503.2. Materials

Binder: The binder used for tack coat shall be a bituminous emulsion or cutback as

specified in the Contract.

503.3.Construction Operation

503.3.1. Preparation of base: The surface on which the tack coat is to be applied

shall be cleaned of dust and any extraneous material before the application of the binder,by using a mechanical broom or any other approved equipment/method as specified bythe Engineer.

503.3.2. Application of binder: Binder may be heated to the temperature

appropriate to the grade of cutback used and approved by the Engineer and spread on thebase at the rate specified in Table 500-2. The normal range of spraying temperature for a

bituminous emulsion shall be 200C 60

0C and for a cutback 50

0C 80

0C if RC-70 /

MC-70 grade is used. It shall be the responsibility of the Contractor to carefully handle

the inflammable bituminous cutback material so as to safeguard against any fire mishap.The binder shall be applied uniformly with the aid of either self-propelled or towed

bitumen pressure sprayer with self-heating arrangement and spraying bar with nozzleshaving constant volume or pressure system, capable of spraying bitumen at specified

rates and temperature so as to provide a uniformly unbroken spread of bitumen. Workshould be planned so that no more than the necessary tack coat for the days operation is

placed on the surface. After application and prior to succeeding construction allow thetack coat to cure, without being disturbed, until the water/cutter has completely

evaporated, as determined by the Engineer.


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TABLE 500-2. RATE OF APPLICATION OF TACK COAT

Type SurfaceQuantity of liquid bituminous material in

Kg per 10 sq. m. area

i) Normal bituminous surfaces 2.0 to 2.5

ii) Dry and hungry bituminous surfaces 2.5 to 3.0

iii) Granular surfaces treated with primer 2.5 to 3.0

iv) Non bituminous surfacesa) Granular base (not primed) 3.5 to 4.0

b) Cement concrete pavement 3.0 to 3.5

Note : There is no need to apply a tack coat on a freshly laid bituminous course if the subsequent

bituminous course is overlaid the same day without opening it to traffic.

503.4. Quality Control of Work

Control on the quality of materials and works shall be exercised by the Engineer inaccordance with Section 900.

503.5. Arrangements for Traffic

During the period of construction, the arrangement of traffic shall be done to Clause112.

503.6. Measurement for Payment

Tack coat shall be measured in terms of surface area of application in square

metres.

503.7.Rate

The contract unit rate for tack coat shall be payment in full for carrying out therequired operations including full compensation for all components listed in Clause 401.8

(i) to (v) as applicable to the work specified in these Specifications.

504. BITUMINOUS MACADAM

504.1. Scope

The work shall consist of construction, in a single course, of compacted crushedaggregates premixed with a bituminous binder, to serve as base/binder course, laidimmediately after mixing, on a base prepared previously in accordance with the

requirement of these Specifications and in conformity with the lines, grades and cross-sections shown on the drawing or as directed by the Engineer.


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504.2. Materials

504.2.1. Bitumen: The bitumen shall be paving bitumen of suitable penetration

grade (30/40 to 80/100) as per IS: 73. The actual grade of bitumen to be used shall bedecided by the Engineer appropriate to the region, traffic, rainfall and other

environmental conditions. Guidelines on selection of the grade of bitumen are given in

Appendix-4.

504.2.2. Aggregates

504.2.2.1. The aggregates shall consist of crushed stone, crushed gravel/shingle or

other stones. They shall be clean, strong, durable, of fairly cubicle shape and free fromdisintegrated pieces, organic or other deleterious matter and adherent coating. If crushed

shingle/gravel is used, not less than 90 per cent by weight of the gravel/shingle piecesretained on 4.75 mm sieve shall have at least two fractured faces. The aggregates shall

preferably be hydrophobic and of low porosity. If hydrophilic aggregates are to be used,the bitumen shall preferably be treated with anti-stripping agents of approved quality in

suitable dose as per Appendix-5. The aggregates shall satisfy the physical requirementsset forth in Table 500.3.

TABLE 500.3. PHYSICAL REQUIREMENTS OF AGGREGATES FOR

BITUMINOUS MACADAM

S. No. Test Test Method Requirement

1. Los Angeles Abrasion Value * IS : 2386 (Part 4) 40 per cent Maximum

2. Aggregate Impact Value * IS : 2386 (Part 4) 30 per cent Maximum

3. Flakiness and Elongation **

Indices (Total)

IS : 2386 (Part - 1) 30 per cent Maximum

4. Coating and Stripping of Bitumen

Aggregate Mixtures

AASHTO T 182 Minimum retained

coating 95 per cent5. Soundness

(i) Loss with Sodium Sulphate 5 cycles

(ii) Loss with Magnesium Sulphate 5 cycles

IS : 2386 (Part 5)

12 per cent Maximum

18 per cent Maximum

6. Water absorption IS : 2386 (Part 3) 2 per cent Maximum

* Aggregates may satisfy requirements of either of the two tests.** To determine this combined proportion, the flaky stone from a representative sample should first

be separated out. Flakiness index is weight of flaky stone metal divided by weight of stone

sample. Only the elongated particles be separated out from the remaining (non-flaky) stone metal.

Elongation index is weight of elongated particles divided by total non-flaky particles. The value of

flakiness index and elongated index so found are added up.Note: If crushed slag is used, Clause 404.2.3. shall apply.

504.2.2.2. The aggregate for bituminous macadam shall conform to one of the twogradings in Table 500-4, depending on the compacted thickness; the actual grading shall

be as specified in the Contract.

504.2.3. Proportioning of materials: The bitumen content for premixing shall be 3to 3.5 per cent by weight of the total mix except when otherwise directed by the

Engineer.


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TABLE 500-4. AGGREGATE GRADING FOR BITUMINOUS MACADAM

Per cent by weight passing the sieve

IS Sieve Designation Grading 1 Grading 245.0 mm 100 -

26.5 mm 75 - 100 100

22.4 mm 60 - 95 75 100

11.2 mm 30 - 55 50 85

5.6 mm 15 - 35 20 40

2.8 mm 5 - 20 5 20

90.0 micron 0 - 5 0 5

The maximum compacted thickness of a layer shall be 100 mm.

The quantities of aggregates to be used shall be sufficient to yield the specifiedthickness after compaction.

504.2.4. Variation in proportioning of material: The Contractor shall have the

responsibility for ensuring proper proportioning of materials and producing a uniformmix. A variation in binder content + 0.3 per cent by weight of total mix shall, however,

be permissible for individual specimens taken for quality control tests vide Section 900.


504.3.1. Weather and seasonal limitations: The work of laying shall not be taken

up during rainy or foggy weather or when the base course is damp or wet, or during duststorm or when the atmospheric temperature in shade is 10

0C or less.

504.3.2. Preparation of the base: The base on which bituminous macadam is to belaid shall be prepared, shaped and conditioned to the specified lines, grades and cross-

sections in accordance with Clause 501, and a priming coat where needed shall beapplied in accordance with Clause 502 as directed by the Engineer.

504.3.3. Tack coat: A tack coat as per Clause 503 shall be applied over the base.

504.3.4. Preparation and transport of mix: Bituminous macadam mix shall be

prepared in a hot mix plant of adequate capacity and capable of yielding a mix of properand uniform quality with thoroughly coated aggregates.

Hot mix plant shall be of suitable capacity preferably of batch mix type. Total

system for crushing of stone aggregates and feeding of aggregate fractions in requiredproportions to achieve the desired mix, deployed by the Contractor must be capable of

meeting the overall Specification requirements under stringent quality control. The plantshall have the following essential features:


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A General

(a) The plant shall have coordinated set of essential units capable of producing uniform mix as

per the job mix formula.

(b) Cold aggregate feed system with minimum 4 bins having belt conveyor arrangement forinitial proportioning of aggregates from each bin in the required quantities. In order to have

free flow of fines from the bin, it is advisable to have vibrator fitted on bin to intermittentlyshake it.

(c) Belt conveyors below each bin should have variable speed drive motors. There should be

electronic load sensor on the main conveyer for measuring the flow of aggregates.

(d) Dryer unit with burner capable of heating the aggregate to the required temperature without

any visible unburnt fuel or carbon residue on the aggregate and reducing the moisture

content of the aggregate to the specified minimum.

(e) The plant shall be fitted with suitable type of thermometric instruments at appropriate

places so as to indicate or record/register the temperature of heated aggregate, bitumen andmix.

(f) Bitumen supply unit capable of heating, measuring/metering and spraying of bitumen at

specified temperature with automatic synchronisation of bitumen and aggregate feed in the

required proportion.

(g) A filler system suitable to receive bagged or bulk supply of filler material and its

incorporation to the mix in the correct quantity wherever required.

(h) A suitable built-in dust control system for the dryer to contain/recycle permissible fines intothe mix. It should be capable of preventing the exhaust of the fine dust into atmosphere for

environmental control wherever so specified by the Engineer.

(i) The plant should have centralised control panel/cabin capable of presetting,

controlling/synchronising all operations starting from feeding of cold aggregates to the

discharge of the hot mix to ensure proper quality of mix. It should have indicators for any

malfunctioning in the operation.

(j) Every hot mix plant should be equipped with siren or horn so that the operator may use the

same before starting the plant every time in the interest of safety of staff.

B For Batch Type Plant

(i) Gradation control unit having minimum four deck vibratory screens for accurate sizing ofhot aggregate and storing them in separate bins. This unit should be fully covered to reduce

the maintenance cost and for better environmental condition.

(ii) Proper arrangement for accurate weighing of each size of hot aggregate from the controlpanel before mixing.

(iii) Paddle mixer unit shall be capable of producing a homogeneous mix with uniform coating

of all particles of the mineral aggregate with binder.


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C For Continuous Type Plant

(i) Gradation control unit having minimum four deck vibratory screens for accurate sizing of

hot aggregate and storing them in separate bins. This unit should be fully covered to reducethe maintenance cost and for better environmental condition.

(ii) Proper arrangement for accurate weighing of each size of hot aggregate from the control

panel before mixing.

(iii) Paddle mixer unit shall be capable of producing a homogeneous mix with uniform coatingof all particles of the mineral aggregate with binder.

D For Drum Mix Plant

(i) It is a prerequisite that only properly screened and graded materials are fed to the bins. If

required, a vibratory screening unit shall be installed at the plant site to ensure the same.

A primary 4-deck vibratory screening unit shall be installed before the multiple bin coldfeed system for screening the aggregates and grading the same.

(ii) Belt conveyers below each bin should have speed drive motors. There should be electronic

load sensor on the main conveyer for measuring the flow of aggregate.

(iii) There should be arrangement to measure moisture content of the aggregate(s) so that

moisture correction may be applied for working out requirements of binder and filler.

The temperature of binder at the time of mixing shall be in the range of 1500C to

1630C and that of the aggregate in the range of 1550C to 1630C. provided that thedifference in temperature between the binder ad aggregate at no time exceeds 140C.

Mixing shall be thorough to ensure that a homogeneous mixture is obtained in

which all particles of the aggregates are coated uniformly, and the discharge temperatureof mix shall be between 130

0C to 160

0C.

The mixture shall be transported from the mixing plant to the point of use insuitable tipper vehicles. The vehicles employed for transport shall be clean and be

covered in transit if so directed by the Engineer. Any tipper causing excessivesegregation of materials by its spring suspension or other contributing factors or that

which shows undue delay shall be removed from the work until such conditions arecorrected.

504.3.5. Spreading: The mix transferred from the tipper at site to the paver shall be

spread immediately by means of self-propelled mechanical paver with suitable screedscapable of spreading, tamping, and finishing the mix true to the specified lines, grades

and cross-sections. The paver finisher shall have the following essential features:

(a) Loading hoppers and suitable distributing mechanism.


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(b) All drives having hydrostatic drive/control.

(c) The machine shall have a hydraulically extendable screed for appropriate width

requirement.

(d) The screed shall have tamping and vibrating arrangement for initial compaction to the

layer as it is spread without rutting or otherwise marring the surface. It shall haveadjustable amplitude and variable frequency.

(e) The paver shall be equipped with necessary control mechanism so as to ensure that the

finished surface is free from surface blemishes.

(f) The paver shall be fitted with an electronic sensing device for automatic levelling and

profile control within the specified tolerances.

(g) The screed shall have the internal heating arrangement.

(h) The paver shall be capable of laying either 2.5 to 4.0 m width or 4.0 to 7.0 m width as

stipulated in the Contract.

(i) The paver shall be so designed as to eliminate skidding/slippage of the tyres during

operation.

However, in restricted locations and in narrow widths where the available plantcannot be operated in the opinion of the Engineer, he may permit manual laying of the

mix.

The temperature of the mix at the time of laying shall be in the range of 1200C to

1600C. In multi-layer construction, the longitudinal joint in one layer shall offset that in

the layer below by about 150 mm. However, the joint in the top-most layer shal be at thelane line of the pavement.

Longitudinal joints and edges shall be constructed true to the delineating line

parallel to the centre line of the road. All joints shall be cut vertical to the full thicknessof the previously laid mix and the surface painted with hot bitumen before placing fresh

material. Longitudinal and transverse joints shall be offset by at least 250 mm from thosein the lower courses and the joint on the top-most layer shall not be allowed to fall within

the wheel path. All transverse joints shall be cut vertically to the full thickness of thepreviously laid mix with asphalt cutter/pavement breaker and surface painted with hot

bitumen before placing fresh material. Longitudinal joints shall be preferably hot joints.Cold longitudinal joints shall be properly heated with joint heater to attain a suitable

temperature of about 800C before laying of adjacent material.

504.3.6. Compaction: After the spreading of mix, rolling shall be done by 80 to100 kN rollers or other approved equipment. Rolling shall start as soon as possible after

the material has been spread deploying a set of rollers as the rolling is to be completed inlimited time frame. The roller shall move at a speed not more than 5 km/h. Rolling shall

be done with care to avoid unduly roughening of the pavement surface.

Rolling of the longitudinal joints shall be done immediately behind the pavingoperation. After this, the rolling shall commence at the edges and progress towards the


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centre longitudinally except that on superelevated and uni-directional cambered portions,

it shall progress from the lower to the upper edge parallel to the centre line of thepavement.

The initial or break-down rolling shall be done with 80 100 kN static weight

smooth wheel roller (3 wheels or tandem), as soon as it is possible to roll the mix without

cracking the surface or having the mix pick up on the roller wheels. The second orintermediate rolling shall follow the break-down rolling with vibratory roller of 80 to 100kN static weight or pneumatic tyred roller of 150 to 250 kN weight, with minimum 7

wheels and minimum tyre pressure of 0.7 MPa as closely as possible to the paver and bedone while the paving mix is still at a temperature that will result in maximum density.

The final rolling shall be done while material is still workable enough for removal ofroller marks, with 60 80 kN tandem roller. During the final rolling, vibratory system

shall be switched off. The joints and edges shall be rolled with a 80 to 100 kN staticroller.

When the roller has passed over the whole area once, any high spots or depressions

which become apparent shall be corrected by removing or adding mix material. Therolling shall then be continued till the entire surface has been rolled to 95 per cent of the

average laboratory density (obtained from Marshall specimens compacted as defined inTable 500-10), there is no crushing of aggregates and all roller marks have been

eliminated. Each pass of the roller shall uniformly overlap not less than one-third of thetrack made in the preceding pass. The roller wheel shall be kept damp if necessary to

avoid bituminous material from sticking to the wheels and being picked up. In no caseshall fuel, lubricating oil be used for this purpose, nor excessive water poured on the

wheels.

Rolling operations shall be completed in every respect before the temperature of the

mix falls below 1000

C.

Roller(s) shall not stand on newly laid material while there is a risk that surface will

be deformed thereby. The edges along and transverse of the bituminous macadam laidand compacted earlier shall be cut to their full depth so as to expose fresh surface which

shall be painted with a thin surface coat of appropriate binder before the new mix isplaced against it.

504.4. Surface Finish and Quality Control Work

The surface finish of construction shall conform to the requirements of Clause 902.

Control on the quality of materials and works shall be exercised by the Engineer inaccordance with Section 900.

504.5. The bituminous macadam shall be covered with either the next pavement

course or wearing course, as the case may be, without any delay. If there is to be anydelay, the course shall be covered by a seal coat to the requirement of Clause 513 before

allowing any traffic over it. The seal coat in such cases shall be considered incidental tothe work and shall not be paid for separately.


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504.6. Arrangements of Traffic

During the period of construction, arrangement of traffic shall be done to Clause112.


The work shall be measured as finished work in cubic metres or by weight in metric

tonnes as provided in the Contract.

504.8. Rate

The contract unit rate for the work shall be payment in full for carrying out therequired operations including full compensation for:

(i) Making arrangements for traffic to Clause 112 except for initial treatment to verge, shoulders

and construction of diversions;

(ii) Preparation of base except for laying of profile correct ive course but including filling of

potholes;

(iii) Providing all materials to be incorporated in the work including arrangement for stock yards,

all royalties, fees, rents where necessary and all leads and lifts;

(iv) All labour, tools, equipment, plant including installation of hot mix plant, power supply units

and all machineries, incidental to complete the work to the Specifications;

(v) Carrying out the work in part widths of the road where directed;

(vi) Carrying out all tests for control of quality; and

(vii) The rate shall cover the provision of bitumen at 3.25 per cent of weight of total mix, with the

provision that the variation of quantity of bitumen will be assessed and the payment adjusted

as per the rate of bitumen quoted.

505.BITUMINOUS PENETRATION MACADAM

505.1. Scope

The work shall consist of construction of one or more layers of compacted crushed

coarse aggregates with alternate applications of bituminous binder and key aggregates inaccordance with the requirements of these Specifications to serve as base/binder course

and in conformity with the lines, grades and cross-sections shown on the drawings or asdirected by the Engineer. Thickness of an individual course shall not exceed 75 mm.

505.2. Materials

505.2.1. Bitumen: The binder shall be paving bitumen of suitable penetration grade

within the range of S-35 to S-90 or A-35 to A-90 (30/40 to 80/100) as per Indian


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Standards Specifications for Paving Bitumen IS: 73, or approved cutbacks satisfying

the requirements of IS: 73, 217 or 454. The actual grade of bitumen or cutbacks to beused shall be decided by the Engineer, appropriate to the region, traffic, rainfall and other

environmental conditions. Guidance in this regard may be obtained fromAppendix 4.

505.2.2. Aggregates

505.2.2.1. The aggregates shall satisfy the physical requirements set forth in Clause504.2.2.1 and Table 500-3.

505.2.2.2. The coarse and key aggregates shall conform to the grading given in

Table 500-5.

505.2.3. Quantities of materials: The quantities of materials used for this workshall be as specified in Table 500-6.


505.3.1. Weather and seasonal limitations: Clause No. 504.3.1 shall apply.

505.3.2. Preparation of the base: The base on which the Penetration macadam

course is to be laid shall be prepared, shaped and conditioned to the specified lines,grades and sections to Clause 501 or as directed by the Engineer. A priming coat where

needed shall be applied over the base in accordance with Clause 502 or as directed by theEngineer. A tack coat as per Clause 503 shall be applied.

TABLE 500-5. GRADING REQUIREMENTS OF COARSE AGGREGATES AND

KEY AGGREGATES FOR BITUMINOUS PNETRATION MACADAM

Per cent by weight passing the Sieve

For 50 mm compacted

thickness

For 75 mm compacted

thicknessIS SieveDesignation

CoarseAggregate

KeyAggregate

CoarseAggregate

KeyAggregate

63 mm - - 100 -

53 mm - - - -

45 mm 100 - 58 - 82 -

26.5 mm 37 - 72 - - 100

22.4 mm - 100 5 - 27 50 7513.2 mm 2 - 20 50 - 75 - -

11.2 mm - - - 5 25

5.6 mm - 5 - 25 - -

2.8 mm 0 - 5 0 - 5 0 - 5 0 5


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TABLE 500-6. QUANTITIES OF MATERIALS REQUIRED FOR 10 sq.m. OF

ROAD SURFACE FOR BITUMINOUS PENETRATION MACADAM

BASE/BINDER COURSE

Compacted

thickness

Binder / Straight run

bitumenCoarse Aggregate Key Aggregate

50 mm 50 kg 0.60 cu. m. 0.15 cu. m.75 mm 68 kg 0.90 cu. m. 0.18 cu. m.

505.3.3. Spreading and compacting coarse aggregates: The coarse aggregate ina dry and clean form shall be spread uniformly and evenly at the rate specified in Table

500-6 preferably with the help of a self-propelled or tipper tail mounted aggregatespreader capable of spreading aggregate uniformly at the specified rates over the required

widths. The surface of the layer shall be carefully checked with camber templates and allhigh and low spots remedied by removing or adding aggregates as may be required. The

spreading shall be carried no further in advance of the rolling and penetrating operations

than can be completed in one average days work. Segregated aggregates or aggregatesmixed with earth or other foreign substances shall be removed and replaced with gradedaggregates.

505.3.4. Compaction: After the spreading of coarse aggregates, dry rolling shall

be done by 80 100 kN smooth-wheeled steel roller. Rolling shall start as soon aspossible after the material has been spread. The rolling shall commence at the edges,

parallel to the centre line of the road and progress towards the centre longitudinallyexcept on superelevated and uni-directional cambered portions, where it shall progress

from the lower to the upper edge after the edges have been rolled. For superelevatedportions, the overlapping should be approximately one-third of the width of the rear

wheel on each trip.

After initial dry rolling, the surface shall be checked with a crown template and a3 metre straight-edge. The surface shall not vary more than 10 mm from the template or

straight-edge. All surface irregularities exceeding the above limit shall be corrected byremoving or adding aggregates as required.

The rolling shall be done until the compacted coarse aggregate has firm surface

true to the cross section shown on the plans and that it has a texture that will allow freeand uniform penetration of the bituminous material.

505.3.5. Application of bituminous material: After the coarse aggregate hasbeen rolled and checked, the bituminous binder shall be applied at specified temperatureas directed by the Engineer. The rate of application shall be as specified in Table 500-6.

At the time of applying the binder, the aggregates shall be surface dry for full

depth of the layer.

The bituminous material shall preferably be applied by a pressure distributoruniformly over the surface at the specified rate. Over small areas, where the use of a


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spray bar is impracticable, the bituminous material shall be applied by the nozzle

attachment. Only when permitted, pouring pots may be used according to the directionsof the Engineer.

505.3.6. Application of key aggregates: Immediately after the first penetration

of bitumen, the key aggregates in a clean and dry state shall be spread uniformly over the

surface by means of an approved mechanical spreader or by approved manual methods atthe rate specified in Table 500-6.

If necessary, the surface shall be broomed to ensure uniform application of thekey aggregates. The entire surface shall then be rolled with a 80 100 kN smooth steel

wheel roller (along with vibratory roller if available) to the Specifications conforming toClause 505.3.4.

505.4. Surface Finish and Quality Control

The surface finish of construction shall conform to the requirements of Clause

902.

Controls on the quality of materials and works shall be exercised by the Engineerin accordance with Section 900.

505.5. The Penetration Macadam shall be provided with final surfacing

(binder/wearing course) without any delay. If there is to be any delay, the course shall becovered by a seal coat to the requirements of Clause 513 before allowing any traffic over

it. The seal coat in such cases shall be considered incidental to the work and shall not bepaid for separately.


During the period of construction, arrangements for traffic shall be done to Clause

112.


Penetration Macadam Base/Binder Course shall be measured as finished work insquare metres.

505.8. Rate

The contract unit rate for Penetration Macadam Course shall be payment in full

for carrying out the required operations including full compensation for all componentslisted in Clause 504.8 (i) to (vi).


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506. BUILT-UP SPRAY GROUT

506.1. Scope

This work shall consist of a two-layer composite construction of compacted crushed

coarse aggregates with application of bituminous binder after each layer and key

aggregates on top for the second layer, in accordance with the requirements of theseSpecifications to serve as a base course and in conformity with the lines, grades andcross-sections shown on the drawings or as directed by the Engineer. Thickness of the

course shall be 75 mm.

Built-up spray grout shall be used in a single course in a pavement structure.

506.2. Materials

506.2.1 Bitumen: Clause 504.2.1 shall apply.

506.2.2. Aggregates: The coarse aggregate shall conform to Clause 504.2.2.1.

The aggregate shall satisfy the physical requirements set out in Table 500-3. Thecoarse and key aggregates for built-up spray grout shall conform to the grading given in

Table 500-7.

TABLE 500-7. GRADING REQUIREMENTS OF COARSE AND KEY

AGGREGATES FOR BUILT-UP SPRAY GROUT

Per cent by weight passing the SieveIS Sieve Designation

Coarse Aggregate Key Aggregate

53.0 mm 100 -

26.5 mm 40 - 75 -

22.4 mm - 100

13.2 mm 0 - 20 40 75

5.6 mm - 0 20

2.8 mm 0 - 5 0 5


506.3.1. Weather and seasonal limitations: Clause 504.3.1 shall apply.

506.3.2. Preparation of base: The base on which the built-up spray grout courseis to be laid shall be prepared, shaped and conditioned to the specified lines, grades and

cross-sections in accordance with Clause 501. A priming coat where needed shall beapplied in accordance with Clause 502 with suitable primer as directed by the Engineer.

506.3.3. Tack coat: A tack coat over the base shall be applied as per Clause 503.


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506.3.4. Spreading and rolling coarse aggregates for the first layer:Immediately after the application of tack coat, the coarse aggregates in a dry and cleanform shall be spread uniformly and evenly preferably by mechanical means at the rate of

0.5 cu. m. per 10 sq. m. area. The surface of the layer shall be carefully checked withtemplates and all high and low spots remedied by removing or adding aggregates as may

be required.

Immediately after spreading of the aggregates, the entire surface shall be rolledwith a 80 100 kN smooth-wheeled roller. Rolling shall commence at the edges and

progress towards the centre except in superelevated and uni-directional camberedportions where it shall proceed from the lower edge to the higher edge. Each pass of the

roller shall uniformly overlap not less than one-third of the track made in the precedingpass.

After initial rolling, the surface shall be checked transversely and longitudinally

with templates and any irregularities corrected by loosening the surface, adding orremoving necessary amounts of aggregate, followed by rolling.

Rolling shall be stopped before voids in the aggregate layer are closed to such an

extent as to prevent free and uniform penetration of the binder.

506.3.5. Application of binder first spray: The binder shall be heated to thetemperature appropriate to grade of bitumen approved by the Engineer and sprayed on

aggregate layer at the rate of 15 kg/10 sq. m. (in terms of straight-run bitumen) in auniform manner with the help of mechanical sprayers capable of spraying bitumen

uniformly at specified rates and temperatures. Excessive deposits of binder caused bystopping or starting of the sprayers or through leakage or any other reason shall be

corrected promptly.

506.3.6. Spreading and rolling of coarse aggregate for the second layer: Immediately after the first application of the binder, the second layer of coarse aggregates

shall be spread and rolled to Clause 506.3.4.

506.3.7. Application of binder-second spray: The second aggregate layer shallthen be given a binder spray at the rate of 15 kg/10 sq. m. (in terms of straight-run

bitumen) to Clause 506.3.5.

506.3.8. Application of key aggregate: Immediately after second application ofthe binder, key aggregates in a clean and dry state shall be spread uniformly and evenly,

preferably by mechanical means at the rate of 0.13 cu. m./10 sq. m. so as to cover thesurface completely. If necessary, the surface shall e broomed to ensure uniform

application of the key aggregates. The entire surface shall then be rolled with a 80 100kN smooth-wheeled roller to Clause 506.3.4. While rolling is in progress, additional key

aggregates, where required, shall be spread by hand. Rolling shall continue until theentire course is thoroughly compacted and the key aggregates are firmly in position.


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506.4. Surface Finish and Quality Control

The surface finish of construction shall conform to the requirements of Clause

902.Control on the quality of materials and works shall be exercised by the Engineer

in accordance with Section 900.

506.5. The built-up-spray-grout shall be provided with final surfacing without anydelay. If there is to be any delay, the course shall be covered by a seal coat to the

requirement of Clause 513 before allowing any traffic over it. The seal coat in such casesshall be considered incidental to the work and shall not be paid for separately.


During the period of construction, arrangement of traffic shall be done to Clause

112.


Built-up spray grout shall be measured as finished work in square metres.

506.8. Rate

The contract unit rate for built-up spray grout shall be payment in full for carryingout the required operations including full compensation for all components listed in

Clause 504.8 (i) to (vi).

507. DENSE BITUMINOUS MACADAM

507.1. Scope

This work shall consist of construction in a single course of 50 to 100 mm thick

base/binder course to the following Specifications on a previously prepared base.

507.2. Materials

507.2.1. Bitumen: The bitumen shall be paving bitumen of Penetration Grade S 65or A 65 (60/70) as per Indian Standard Specifications for Paving Bitumen IS: 73. In

case of non-availability of bitumen of this grade, S 90 (80/100) grade bitumen may beused with the approval of the Engineer. Guidance to selection of the grade of bitumen

may be taken fromAppendix 4.

507.2.2. Coarse aggregates: The coarse aggregates shall consist of crushed stone,crushed gravel/shingle or other stones. They shall be clean, strong, durable, of fairly

cubical shape and free from disintegrated pieces, organic or other deleterious matter andadherent coating. The aggregates shall preferably be hydrophobic and of low porosity. If

hydrophilic aggregates are to be used, the bitumen shall be treated with antistripping


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agents of approved quality in suitable doses. The aggregates shall satisfy the physical

requirements set forth in Table 500-8.

If crushed gravel/shingle is used, not less than 90 per cent by weight of thegravel/shingle pieces retained on 4.75 mm sieve shall have at least two fractured faces.

The portion of the total aggregate passing 4.75 mm sieve shall have a sand equivalent

value of not less than 50 when tested in accordance with the requirement of IS: 2720(Part-37).

The plasticity index of the fraction passing the 425 micron sieve shall not exceed 4.

TABLE 500.8. PHYSICAL REQUIREMENTS OF AGGREGATES FOR

DENSE BITUMINOUS MACADAM

S. No. Test Test Method Requirement

1. Los Angeles Abrasion Value * IS : 2386 (Part 4) 40 per cent Maximum

2. Aggregate Impact Value * IS : 2386 (Part 4) 30 per cent Maximum3. Flakiness and Elongation **

Indices (Total)

IS : 2386 (Part - 1) 30 per cent Maximum

4. Coating and Stripping of Bitumen

Aggregate Mixtures

AASHTO T 182 Minimum retained

coating 95 per cent

5. Soundness

(i) Loss with Sodium Sulphate 5 cycles

(ii) Loss with Magnesium Sulphate 5 cycles

IS : 2386 (Part 5)

12 per cent Maximum

18 per cent Maximum

6. Water absorption IS : 2386 (Part 3) 2 per cent Maximum

* Aggregates may satisfy requirements of either of the two tests.** To determine this combined proportion, the flaky stone from a representative sample should first

be separated out. Flakiness index is weight of flaky stone metal divided by weight of stone

sample. Only the elongated particles be separated out from the remaining (non-flaky) stone metal.Elongation index is weight of elongated particles divided by total non-flaky particles. The value of

flakiness index and elongated index so found are added up.

507.2.3. Fine aggregates: Fine aggregates shall be the fraction passing 2.36 mmsieve and retained on 75 micron sieve, consisting of crusher-run screening, gravel, sand

or a mixture of both. These shall be clean, hard, durable, uncoated, dry and free from anyinjurious, soft or flaky pieces and organic or other deleterious substances.

507.2.4. Filler: Filler shall consist of finely divided mineral matter such as rock

dust, hydrated lime or cement as approved by the Engineer.

The filler shall be graded within the following limits:

IS Sieve Per cent passing by weight

600 micron 100

300 micron 95 100

75 micron 85 100

The filler shall be free from organic impurities and have a Plasticity Index notgreater than 4. The Plasticity Index requirement shall not apply if filler is cement or lime.

When the coarse aggregate is gravel, 2 per cent by mass of total aggregate of Portland


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cement of hydrated lime shall be added and the percentage of fine aggregate reduced

accordingly. Cement or hydrated lime is not required when the gravel is limestone.

507.2.5. Aggregate gradation: The combined coarse and fine aggregates and filler(when used) shall produce a mixture to conform to the grading set forth in Table 500-9.

TABLE 500-9. AGGREGATE GRADATION FOR DENSE BITUMINOUSMACADAM

Sieve Designation Percentage passing the sieve by weight

37.5 mm 100

26.5 mm 90 100

13.2 mm 56 80

4.75 mm 29 59

2.36 mm 19 45

300 micron 5 17

75 micron 1 - 7

The aggregate mix, as used in work, shall not vary from the low limit on one sieve to the high limit on theadjacent sieve but shall be well graded.

507.3. Mix Design

507.3.1. Requirement of mix: Apart from conformity with grading and qualityrequirements of individual ingredients, the mix shall meet the requirements set out in

Table 500-10.

TABLE 500-10. REQUIREMENTS OF DENSE BITUMINOUS MACADAM

MIX

S. No. Description Requirement

1.

Marshall stability (ASTM Designation D-1559)determined on Marshall specimens compacted

by 75 compaction blows on each end

820 kg (1800 lb)minimum

2. Marshall flow (mm) 2 - 4

3. Per cent Air voids 3 5

4. Minimum voids in mineral aggregates (VMA) 10 per cent 12 per cent

5.Per cent voids in mineral aggregates filled bybitumen (VFB)

65 75

6. Binder content per cent by weight of total mix Not less than 4.0 per cent

507.3.2. Binder content: The binder content shall be so fixed as to achieve therequirements of the mix set out in Table 500-10. Marshall method for arriving at the

binder content shall be adopted, replacing the aggregates retained on 26.5 mm sieve bythe aggregates passing 26.5 mm sieve and retained on 22.4 mm seve.


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507.3.3. Job mix formula: The Contractor shall intimate to the Engineer in writing,

at least 20 days before the start of the work, the job mix formula proposed to be used byhim for the work and shall give the following details:

(i) Source and location of all materials;(ii) Proportions of all materials expressed as follows where each is applicable:

(a) Binder, as percentage by weight of total mix;(b) Coarse aggregate/Fine aggregate/Mineral filler as percentage by weight of total

aggregate including mineral filler;

(iv) A single definite percentage passing each sieve for the mixed aggregate;(v) The results of tests enumerated in Table 500-10 as obtained by the Contractor;(vi) Test results of physical characteristics of aggregates to be used;(vii) Mixing temperature and compacting temperature.

While working out the job mix formula, the Contractor shall ensure that it is based

on a correct and truly representative sample of the materials that will actually be used inthe work and that the mix and its different ingredients satisfy the physical and strength

requirements of these Specifications.

Approval of the job mix formula shall be based on independent testing by theEngineer for which samples of all ingredients of the mix shall be furnished by the

Contractor as required by the former.

The approved job mix formula shall remain effective unless and until modified bythe Engineer. Should a change in the source of materials be proposed, a new job mix

formula shall be established and got approved from the Engineer before actually usingthe materials.

507.3.4. Permissible variation from job mix formula: It shall be the

responsibility of the Contractor to produce a uniform mix conforming to the approved jobmix formula subject to the permissible variations of the individual percentages of the

various ingredients in the actual mix from the job mix formula to be used within thelimits as specified in Table 500-11. These variations are intended to apply to individual

specimens taken for quality control tests vide Section 900.


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TABLE 500-11. PERMISSIBLE VARIATIONS FROM THE JOB MIX

FORMULA

S. No. Description of ingredients

Permissible variation by

weight of total mix-in per

cent

1. Aggregate passing 13.2 mm sieve and large sieves + 8

2. Aggregate passing 11.2 mm sieve and 5.6 mm sieve + 7

3. Aggregate passing 2.80 mm sieve and 1.40 mm sieve + 6

4. Aggregate passing 710 micron sieve and 355 micron sieve + 5

5. Aggregate passing 180 micron sieve + 4

6. Aggregate passing 90 micron sieve + 2

7. Binder + 0.3

8. Mixing temperature + 100C


507.4.1. Weather and seasonal limitations: Clause 504.3.1. shall apply.

507.4.2. Preparation of base: The base on which Dense Bituminous Macadam is

to be laid shall be prepared, shaped and conditioned to the specified lines, grades andcross sections in accordance with Clause 501 or as directed by the Engineer. The surface

shall be thoroughly swept clean free from dust and foreign matter using mechanicalbroom and dust removed or blow off by compressed air. In portions where mechanical

means cannot reach, other approved method shall be used. A priming coat where needed,shall be applied in accordance with Clause 502 or as directed by the Engineer.

507.4.3. Tack coat: A tack coat over the base shall be applied as per Clause 503.

507.4.4. Preparation of mix: Clause 504.3.4. shall apply.

507.4.5. Spreading: The mix transported from the hot mix plant to the site shall be

spread by means of a self-propelled paver with suitable screeds capable of spreading,tamping and finishing the mix to specified grade, lines and cross-section. Paver Finisher

shall have the essential features as spelt out in Clause 504.3.5. However, in restrictedlocations and in narrow widths where the available equipment cannot be operated in the

opinion of the Engineer, he may permit manual laying of the mix. Similarly for smallerjobs, mechanical paver may be used with the approval of the Engineer.

The temperature of mix at the time of laying shall be in the range of 1200C 160

0C.

Mixes with a temperature of less than 1200C shall not be put into paver spreader.

Longitudinal joints and edges shall be constructed true to the delineating lines parallel tothe centre line of the road. Longitudinal and transverse joints shall be offset by at least

250 mm from those in the lower courses and the joint on the top most layer shall not be


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allowed to fall within the wheel path. All transverse joints shall be cut vertically to the

full thickness of the previously laid mix with asphalt cutter and the surface painted withhot bitumen before placing fresh material. Longitudinal joints shall be preferably hot

joints. Cold longitudinal joints shall be properly heated with joint heater to attain asuitable temperature of about 80

0C before laying of adjacent material.

507.4.6. Rolling: After spreading the mix by paver, it shall be thoroughlycompacted by rolling with a set of rollers moving at a speed not more than 5 km/h,immediately following close to the paver. Generally the initial or breakdown rolling shall

be done with 80-100 kN static weight smooth-wheeled roller. The intermediate rollingshall be done with 80 100 kN static weight vibratory roller or with a pneumatic tyred

roller of 150-250 kN weight having a tyre pressure of at least 0.7 MPa. The finish rollingshall be done with 60 80 kN weight smooth wheeled tandem roller. All the compaction

operations, i.e., breakdown rolling and intermediate rolling can be accomplished by usingvibratory tandem roller of 80-100 kN static weight. During initial breakdown rolling and

finish rolling, no vibratory compaction shall be resorted to. The exact pattern of rollingshall be established after trial compaction as approved by the Engineer. Any

displacement occurring as a result of reversing of the direction of a roller or from anyother cause shall be corrected at once as specified and/or removed and made good. The

rollers shall not be permitted to stand on pavement which has not been fully compactedand where temperature is still more than 70

0C. Necessary precautions shall be taken to

prevent dropping of oil, grease, petrol or other foreign matter on the pavement eitherwhen the rollers are operating or standing.

The wheels of roller shall be kept moist to prevent the mix from adhering to them.

But in no case shall fuel/lubricating oil be used for this purpose nor excessive waterpoured on the wheels. Rolling shall commence longitudinally from edges and proceed

towards the centre, except that on superelevated and unidirectional cambered portions, it

shall progress from the lower to upper edge parallel to the centre line of the pavement.The roller shall proceed on the fresh material with rear or fixed wheel leading so as tominimise the pushing of the mix and each pass of the roller shall overlap the preceding

one by half the width of the rear wheel.

Rolling shall be continued till the density achieved is at least 98 per cent of that oflaboratory Marshall specimen (compacted as defined in Table 500-10) and all roller

marks are eliminated. Skin patching of an area that has been rolled will not be permitted.Rolling operations shall be completed in all respects before the temperature of the mix

falls below 1000C.

507.5. Opening to Traffic

Traffic may be allowed after completion of the final rolling when the mix hascooled down to the surrounding temperature. The Dense Bituminous Macadam shall be

provided with an appropriate wearing course as early as possible prior to regular openingto normal traffic and/or impending rain.


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507.6. Surface Finish and Quality Control of Work

The surface finish of construction shall conform to the requirements of Clause 902.

Control on the quality of materials and works shall be exercised by the Engineer in

accordance with Section 900.


During the period of construction, arrangements for the traffic shall be done toClause 112.


Dense Bituminous Macadam shall be measured as finished wok in cubic metres or

tonnes as directed by the Engineer.

507.9. Rate

The contract unit rate for Dense Bituminous Macadam shall be payment in full forcarrying out the required operations including full compensation for all components listed

in Clause 504.8 (i) to (vi). The rate shall cover the provision of bitumen in the mix at 4.5per cent of the weight of the total mix, with the provision that the variation of quantity of

bitumen will be assessed and the payment adjusted as per the rate of bitumen quoted.

508. SURFACE DRESSING

508.1. Single and Two-Coat Surface Dressing using Bitumen

508.1.1 Description: This work shall consist of the application of one coat or two

coats of surface dressing, each coat consisting of a layer of bituminous binder sprayed onbase prepared previously, followed by a cover of stone chippings properly rolled to form

a wearing course to the requirements of these Specifications.

508.1.2. Materials

508.1.2.1. Binder: The binder shall be straight-run bitumen of a suitable gradeappropriate to the region, traffic, rainfall and other environmental conditions as directed

by the Engineer and conforming to IS: 73. Guidance in this regard may be obtained fromAppendix 4.

508.1.2.2. Stone chippings: The stone chippings shall conform to Clause 504.2.2.1.

The Stone Polishing Value as measured by BS: 812 (Part 114), shall not be less than 55.The stone chippings shall also conform to the quality requirements of Table 500-3 except

that water absorption shall be restricted to a maximum of 1 per cent. The size of stonechippings shall be in accordance with Table 500-12.


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508.1.2.3. Quantities of materials: The quantities of materials used for this work

shall be as specified in Table 500-13.

TABLE 500-12. SIZE REQUIREMENTS OF STONE CHIPPINGS FOR

SRFACE DRESSING USING BITUMEN

S.No. Type of constructionNormal size of

stone chippings

Specifications

1.Single coat surface dressing or the first

coat of two-coat surface dressing13.2 mm

100 per cent passing through 22.4 mm

sieve & retained on 11.2 mm sieve.

2.Second coat of two-coat surface

dressing (also used as a renewal coat)11.2 mm

100 per cent passing through 13.2 mm

sieve and retained on 5.6 mm sieve.

TABLE 500-13. QUANTITIES OF MATERIALS REQUIRED FOR 10 sq. m. OF

ROAD SURFACE FOR SURFACE DRESSING USING BITUMEN

S.No. Type of construction Binder Stone chippings

1.Single coat surface dressing or the first coat of the two-

coat surface dressing18.0 kg 0.15 cu. m.

2.Second coat of two-coat surface dressing (also used as

a renewal coat)10.0 kg 0.10 cu. m.

508.1.3. Construction operations

508.1.3.1. Weather and seasonal limitations: Clause 504.3.1 shall apply.

508.1.3.2. Preparation of base: The base on which the surface dressing is to belaid shall be prepared, shaped and conditioned to the specified lines, grade and cross-

section in accordance with Clause 501 and as directed by the Engineer. Priming coat,where needed, shall be provided as per Clause 502 and as directed by the Engineer.

Where the existing surface shows signs of fatting up, this shall be rectified. Thebituminous primed surface to be dressed shall be thoroughly cleaned either by using a

mechanical broom or ay other approved equipment/method as specified by the Engineer.

Dust removed in the process shall be blown off with the help of compressed air.

508.1.3.3. Application of binder: Binder shall be heated to 1500C 163

0C and

sprayed on the dry surface in a uniform manner with the help of self-propelled

mechanical sprayers having self-heating arrangement and bitumen pressure pump andspraying bar with nozzles having constant volume or pressure system capable of spraying

bitumen uniformly at the rates specified in Table 500-13 and above mentionedtemperature. Excessive deposits of binder caused by stopping or starting of the sprayer or

through leakages or any other reason shall be corrected by blotting with sand before the

stone chippings are spread.

508.1.3.4. Application of stone chippings: Immediately after the application of

binder, stone chippings in a dry and clean state shall be spread uniformly on the surfaceby means of a self-propelled or towed mechanical grit spreader capable of spraying

uniformly at rates specified in Table 500-13 so as to cover the surface completely. Ifnecessary, the surface shall be broomed to ensure uniform spread of chippings.


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508.1.3.5. Rolling: Immediately after the application of the cover material, the

entire surface shall be rolled with a 80 100 kN smooth wheeled steel roller, 80 100kN static weight vibratory roller, or other approved equipment. Rolling shall commence

at the edges and progress towards the centre except in superelevated and unidirectionalcambered portions where it shall proceed from the lower edge to the higher edge. Each

pass of the roller shall uniformly overlap not less than one-third of the track made in the

preceding pass. While rolling is in progress, additional chippings shall be spread by handin necessary quantities required to make up irregularities. Rolling shall continue until allaggregate particles are firmly embedded in the binder and present a uniform closed

surface.

508.1.3.6. Application of second coat of surface dressing: Where surface dressingin two coats is specified, the second coat shall be applied immediately after laying of the

first coat. The construction operations for the second coat shall be the same as describedin Clauses 508.1.3.3 to 508.1.3.5.

508.1.4. Opening to traffic: Traffic shall not be permitted to run on any newly

surface dressed area until the following day. In special circumstances, however, theEngineer may open the road to traffic immediately after rolling, but in such cases traffic

speed shall be limited to 16 km per our till the following day.

508.1.5. Surface finish and quality control of work: The surface finish ofconstruction shall conform to the requirements of Clause 902.



508.1.6. Arrangements for traffic: During the period of construction, arrangement

of traffic shall be done as per Clause 112.

508.1.7. Measurements for payment: Each coat of surface dressing shall be

measured as finished work in square metres.

508.1.8. Rates: The contract unit rate for each coat of surface dressing shall bepayment in full for carrying out the required operations including full compensation for

all components listed in Clause 504.8 (i) to (vi).

508.2. Two-Coat Surface Dressing Using Cationic Bitumen Emulsion

508.2.1. Scope

508.2.1.1. This work shall consist of two-coat surface dressing, each coat consistingof a layer of cationic bitumen emulsion binder sprayed on a base prepared previously,

followed by a cover of stone aggregate, properly rolled to form a wearing course to therequirements of these Specifications.

508.2.1.2. It shall, however, not be applicable to a single coat surface dressing using

cationic bitumen emulsion.


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508.2.2. Material

508.2.2.1. Binder: The binder shall be a Cationic type bitumen emulsion of Rapid

Setting (RS) grade complying with IS: 8887 and having bitumen content 60 per centminimum by weight.

508.2.2.2. Aggregate

(A) *General Requirements: Clause 508.1.2.2. shall apply except the size

requirement which shall be as given in Table 500-14. Wet aggregates canbe used for surface dressing with Cationic bitumen emulsions and when

aggregates are dusty, they should be cleaned by washing or by sprinklingwater copiously. If the road surface is dry, a light sprinkling with water

shall be done.

(B) Size: The aggregates shall conform to the size given in Table 500-14.

TABLE 500-14. REQUIREMENTS OF STONE CHIPPINGS FOR SURFACEDRESSING USING BITUMEN EMULSION

1. * For first coat 13.2 mm sizePassing 22.4 mm sieve and retained on11.2 mm sieve.

2. For second coat 6.7 mm sizePassing 9.5 mm sieve and retained on2.36 mm sieve.

(C) Quantities of Materials: The quantities of materials used for this workshall be as given in Table 500-15.

TABLE 500-15. REQUIREMENTS OF MATERIALS USING BITUMEN

EMULSIONMaterial For 10 sq. m area For First Coat For Second Coat

Cationic Bitumen Emulsion 12 to 14 kg 16 to 18 kg

Aggregates 0.10 to 0.12 cu. m. 0.06 to 0.08 cu. m.


508.2.3.1. Weather limitations: Cationic bitumen emulsions should not normally

be stored below 00C. However, surface dressing with Cationic bitumen emulsion shouldbe carried out only when the atmospheric temperature is above 10

0C. The work can be

carried out when the base is damp. All standing water in depressions shall, however, be

removed.

508.2.3.2. Preparation of base: The existing base on which surface dressing is to

be laid shall be prepared, shaped and corrected to a uniform grade and camber inaccordance with Clause 501.

The surface shall be cleaned to remove all loose particles, dust and foreign matter.

It is preferably to spray water on the surface to settle the loose dust and also to exposeclean surface of aggregates in the case of granular base courses.


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508.2.3.3. Preparation of binder: Before opening, the Cationic bitumen emulsion

drums should be rolled at slow speed, to and fro, for a distance of about 10 metres, 5 to 6times to mix the contents properly.

508.2.3.4. First Coat

(A) Application of Binder: Cationic bitumen emulsion binder can be appliedon wet road surface. If the road surface is dry, light sprinkling with watershall be done. Cationic bitumen emulsion shall be sprayed uniformly on

the prepared base by mechanical sprayers. In exceptional cases sprayingfrom a spraying can may be resorted to as directed by the Engineer. The

spraying can should have 6 mm diameter holes spaced 30 mm apart toprevent clogging. An emulsion tank of 30 liters capacity pressurized by

compressed air from a hand pump and a 12 mm flexible pipe with a spraynozzle is a simple and efficient arrangement for spraying.

(B) Application of aggregate: Immediately after spraying of Cationic

emulsion, aggregate of 13.2 mm size shall be spread uniformly and evenlyby mechanical means to cover the surface completely and evenly. Any

oversize aggregate, if seen, shall be removed.

(C) Rolling: Immediately after the application of cover material, the surfaceshall be rolled with 80-100 kN roller preferably by smooth wheeled

tandem type. The rolling shall begin at the edge and proceed towards thecentre, parallel to the centre line except in superelevated and

unidirectional cambered portions where it shall proceed from the loweredge to the higher edge. While rolling, aggregates shall be added or

removed so as to ensure a uniformly covered surface. Each-pass of roller

shall uniformly overlap not less than one third of the track made in thepreceding pass. Rolling shall continue for just enough time to embed theaggregates in the binder and present a uniform closed surface. Excessive

rolling, resulting in crushing of aggregates shall be avoided.

508.2.3.5. Second Coat

(A) Time interval: The second coat of surface dressing shall be applied on thesame day as the first coat but at least not earlier than one hour after

finishing the rolling of the first coat.

(B) Application of emulsion: Traffic shall not be allowed on the first coatbefore the application of second coat. If the aggregates of the first coat

appear to be loose and unbonded in few spots, the same shall not bedisturbed.

The Cationic bitumen emulsion for second coat shall be sprayed by

mechanical sprayer or in exceptional cases by using pouring can with theapproval of the Engineer, taking care not to disturb the first layer while

walking over it.


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(C) Application of aggregate: Immediately after the application of emulsion,

6.7 mm size aggregates shall be spread uniformly by mechanical means tocover the whole surface evenly.

(D) Rolling: Rolling shall start soon after spreading the aggregates and all

operations carried out as per Clause 508.2.3.4 (C) to achieve a uniform

closed surface.

(E) Finishing: After one pass of the roller, depressions shall be filled with 6.7

mm size aggregate. If excess of aggregate is found in isolated spots, thebigger size aggregates shall be removed to give a uniform surface. Finish

rolling on the next day helps to give a firm surface.

508.2.4. Opening to traffic: The road may be opened to traffic 4 hours after

completing rolling of the second coat, but preferably the next day after 24 hours.

Where the road width is single lane, traffic can be allowed at slow speed of notmore than 10 km per hour making sure to add aggregates and emulsion wherever the

surface has been picked up by traffic.

508.2.5. Surface finish and quality control of work: The surface finish ofconstruction shall conform to the requirements of Clause 902.



508.2.6. Arrangements for traffic: During the period of construction, arrangement

of traffic shall be done to Clause 112.

508.2.7. Measurements for payment: Two coats of surface dressing shall be

measured as a finished work in square metres.

508.2.8. Rate: The contract unit rate for two coats of surface dressing shall bepayment in full for carrying out the required operations including full compensation for

all components listed in Clause 504.8 (i) to (vi).

508.3. Surface Dressing with Precoated Aggregate using Bitumen

508.3.1. Scope

508.3.1.1. The work shall consist of application of either a single coat or two coats

of surface dressing over a previously prepared base, each coat consisting of application ofbituminous binder sprayed on a base previously prepared followed by a cover of

precoated materials properly rolled to form a wearing course to the requirements of theseSpecifications.


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508.3.1.2. This Specification may be adopted in lieu of the conventional surface

dressing to Clause 508.1, in situations where better adhesion is required between theaggregates and binder during construction and later in service. The technique is basically

the same as conventional surface dressing except that a small quantity of binder is usedfor precoating the aggregates. However, it is quite different from premix construction.

508.3.2. Materials

508.3.2.1. Binder: The binder shall be straight run bitumen of a suitable grade

appropriate to the region, traffic and other environmental conditions and as directed bythe Engineer and conforming to IS: 73.

508.3.2.2. Aggregates: The aggregates shall conform to Clause 504.2.2. They shall

conform to the quality requirements of Table 500-3 except that the water absorption shallbe restricted to maximum of 1 per cent. The stone Polishing Value as measured by BS:

812 (Part 114) shall not be less than 55.

The size of the aggregates shall be in accordance with Table 500-12.

508.3.2.3. Quantities of materials: The quantities of materials used for this workshall be as specified in Tables 500-12 and 500-13.

508.3.2.4. Precoating: The aggregates shall be precoated with 0.75 to 1.00 per cent

of their weight with binder and shall not be precoated simultaneously with the surfacedressing operation. The precoated aggregates shall be allowed to cure for at least one

week so that they become non-sticky to facilitate easy spreading like normal uncoatedaggregates. The aggregates, free of dust or fine particles shall be preheated to 160

0C for

precoating and then mixed with bitumen binder (0.75 to 1.00 per cent by weight of

aggregate) heated to its application temperature. The aggregates and binder shall bethoroughly mixed in a mixer of approved type till the aggregates are uniformly coated.


508.3.3.1. Weather and seasonal limitations: Clause 504.3.1 shall apply.

508.3.3.2. Preparation of base: Clause 508.1.3.2 shall apply.

508.3.3.3. Application of binder: After deducting the binder quantity consumed inprecoating aggregates for first coat in terms of para 508.3.2.4 from the quantities

specified in Table 500-13, remaining binder of first coat shall be heated to 1500

C 1650

Cand sprayed on the clean and dry surface in a uniform manner preferably with the help of

mechanical sprayers having self-heating arrangement, bitumen pressure pump and spaynozzle bar capable of spraying bitumen uniformly at the rates and temperatures specified

above. Excessive deposits of binder caused by stoppage or starting of sprayer or throughleakage or any other reason shall be corrected before stone chippings are spread.

508.3.3.4. Application of aggregates: Immediately after the application of binder,

aggregates in a dry and clean state shall be spread uniformly on the surface preferably by


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means of a mechanical gritter capable of spreading uniformly at the rates specified in

Table 500-14 so as to cover the surface completely. If necessary, the surface shall bebroomed mechanically or manually to ensure uniform spread of aggregates.

508.3.3.5. Rolling: Clause 508.1.3.5 shall apply.

508.3.3.6. Application of second coat of surface dressing: The second coat ofsurface dressing, where specified, shall be applied immediately after the first coat or soonafter, depending upon the conditions at site and type of binder used. The construction

operations for the second coat shall be the same as described in Clause 508.3.3.3

specification for base & surface courses

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