acceptance control seals - rnis.westerncape.gov.za

18 Acceptance Control: Seals 08 July, 2004 page i

Department of Transport and Public Works Roads Infrastructure Branch

Materials Manual

Western Cape Provincial Administratio n

Volume 2

Chapter 18

Revision 0

Base

Surfacing

Subbase

Subgrade

Selected

Acceptance Control

Seals

Materials Manual First Edition

Chapter 18 Acceptance Control: Seals

Western Cape Provincial Administration Department of Transport and Public Works Roads Infrastructure Branch

Western Cape Provincial Administration © 2008 by the Western Cape Provincial Administration. All rights reserved First Edition revision 0 published 2008. Printed in the Republic of South Africa SET: ISBN 0-620-29823-5 CHAPTER: ISBN 1-920158-19-7

WCPA Department of Transport and Public Works Materials Manual Volume 2 Chapter 18

TABLE OF CONTENTS

ACCEPTANCE CONTROL: SEALS CONTENTS page 18-

INTRODUCTION ..................................................................................................1

MATERIALS.......................................................................................................3 Introduction..............................................................................................................................................3 Standards ................................................................................................................................................3 Selection And Constraints ......................................................................................................................3 Component Conformance Control ..........................................................................................................4 Sampling..................................................................................................................................................4 Tests........................................................................................................................................................4 Time Schedule To Obtain Acceptance....................................................................................................4 Applicable Forms.....................................................................................................................................5 Assessment.............................................................................................................................................5

Aggregate .................................................................................................................................................... 5 Binders ........................................................................................................................................................ 5 Water ........................................................................................................................................................... 5

DESIGN VERIFICATION (LABORATORY) ...............................................................6 Introduction..............................................................................................................................................6 Application Rates ....................................................................................................................................6 Applicable Forms.....................................................................................................................................6

DESIGN VERIFICATION (TRIAL SECTION) .............................................................8 Introduction..............................................................................................................................................8

Road Surface Conditions ............................................................................................................................. 8 Aggregate .................................................................................................................................................... 8 Binder .......................................................................................................................................................... 8 Distributor .................................................................................................................................................... 9 Chip Spreader.............................................................................................................................................. 9 Trucks.......................................................................................................................................................... 9 Slurry Mixing Plant..................................................................................................................................... 10 Other Plant ................................................................................................................................................ 10

Process and Acceptance Control Software ..........................................................................................10 Trial Run Operation ...............................................................................................................................10

Chip and Spray .......................................................................................................................................... 10 Slurry ......................................................................................................................................................... 11

Acceptance Of Trial Run .......................................................................................................................12 Applicable Forms...................................................................................................................................12

CONSTRUCTION LOTS ......................................................................................14 Process and Acceptance Control Software ..........................................................................................14 Assessment...........................................................................................................................................14 Payment - Acceptance Or Rejection .....................................................................................................14 Applicable Forms...................................................................................................................................14 As-Built Data..........................................................................................................................................14

SUPPLY ONLY - AGGREGATES .........................................................................16 Introduction............................................................................................................................................16 Sampling Plan .......................................................................................................................................16 Sampling Procedures ............................................................................................................................16 Tests......................................................................................................................................................16 Time Schedule To Obtain Acceptance..................................................................................................16 Applicable Forms...................................................................................................................................16 Assessment...........................................................................................................................................17

Grading...................................................................................................................................................... 17 Flakiness Index.......................................................................................................................................... 18

18 Acceptance Control: Seals 06 June 2008 page 18-i

WCPA Transport and Public Works Department Materials Manual Volume 2 Chapter 18

page 18-ii 06 June 2008 18 Acceptance control: seals

Crushed Faces .......................................................................................................................................... 18

FIGURES Figure 18-1: Layout of the Materials Manual.....................................................................................................1 Figure 18-2: Example of completed form E-DET-SUR1-E................................................................................7 Figure 18-3: Marvil Permeability vs In-situ Voids in Asphalts .........................................................................13

TABLES Table 18-1: Tolerances, φ and Rejection Limits ..............................................................................................17

TABLE OF CONTENTS


INTRODUCTION

ACCEPTANCE CONTROL: SEALS

INTRODUCTION This chapter gives the background required to adequately apply the acceptance control process for seals, as well as to identify some problems, and the means to address such problems and provide an acceptable product.

This chapter’s part in the overall layout of the Materials Manual is shown in Figure 18-1 below.

For a road to perform successfully a durable, skid-resistant and all-weather dust free surfacing is required to prolong or increase the life-span of the road.

To achieve this, bituminous surface treatments, or so-called blacktops, are commonly used for new construction and for resealing of existing surfaced roads because they:

• provide the road user with an accept-able level of service; • protect the structural layers of the pavement from the abrasive forces of traffic as well as from the effects of the environment, i.e., by eliminating or re-ducing the ingress of surface water to the lower layers;

• have been proved successful on both rural and urban streets under traffic con-ditions varying from light to heavy; and

• are economically attractive.

Chapter 15 CHEMICALLY

TREATED LAYERS

INPUTS ACTIVITIES

Chapter 8 QUALITY ASSURANCE

ACCEPTANCE CONTROL7 Construction equipment

control

Chapter 13SELECTED LAYERS

Chapter 14SUBBASE LAYERS

Chapter 17 ASPHALT LAYERS

Chapter 19 GRAVEL WEARING

COURSE

Chapter 20 CONCRETE

Chapter 9 BASIC CONCEPTS

Chapter 10 ROADBED

Chapter 12 FILL

INPUTS ACTIVITIES

QUALITY ASSURANCE

ACCEPTANCE CONTROL7 Construction equipment

control

Chapter 13SELECTED LAYERS

Chapter 14SUBBASE LAYERS

Chapter 17 ASPHALT LAYERS

Chapter 19 GRAVEL WEARING

COURSE

Chapter 20 CONCRETE

Chapter 9 BASIC CONCEPTS

Chapter 10 ROADBED

Chapter 12 FILL

Chapter 11 STOCKPILED

MATERIAL

Chapter 16 BASE LAYERS

Chapter 18 SEALS

Figure 18-1: Layout of the Materials Manual

18 Acceptance control: seals 06 June 2008 page 18-1


This chapter deals only with the acceptance of the following seal categories:

Prime

Sand seal

Chip and spray (single and double seals)

Slurry for seals (See Chapter 8: Quality Control)

The following seal categories are not dealt with in this chapter:

Surface enrichment. This treatment is ap-plied merely to extend the life of an existing surface by the sprayed application of a diluted emulsion, inverted emulsion, or cut-back bitu-men, provided the texture is such that the binder can penetrate into the existing seal and not remain on the surface. Continued applica-tion of this treatment can extend the life of the surfacing. The quality of the binder must still conform to the appropriate binder specification (see Chapter 2, “Materials Standards”).

Asphalt layers. This subject is dealt with in Chapter 17, “Acceptance Control - Asphalt Layers.”

Gravel wearing course. This subject is dealt in Chapter 19: “Acceptance Control - Gravel Wearing Course”.

This chapter, therefore, deals with the acceptability of seals and their ability to perform the tasks required of them, be it for new construction or existing surfaced roads. It also covers controls to be exercised on the materials (components) and requirements common to the construction of the above seals and the supply of the materials (binders and aggregates).

INTRODUCTION

page 06 June 2008 18 Acceptance control: seals 18-2


MATERIALS

INTRODUCTION Well before the placing of the seal, the quality of the proposed materials and the design pa-rameters set for the seal need to be verified.

MATERIALS

Samples of the processed and/or delivered aggregates, water from sources not previously tested and binder (emulsions are tested for compatibility with the water) should be obtained and tested.

STANDARDS Guidelines for the materials standards are out-lined in Chapter 2, “Materials Standards”, with respect to the following:

Binders

• Prime Coat • Tack Coat • Spray Grade Emulsion • Stable Grade Emulsions - slow setting

slurry • Stable Grade Emulsions - rapid setting

slurry • Modified Emulsions • Penetration Grade Bitumen • Cut back Bitumen • Modified Hot Binders

Aggregates

• Coarse Aggregate - single sized • Fine Aggregate

• sand for blinding • sand for sand seal • grit • crusher dust for

- fine graded slurry - coarse graded slurry - slow setting - coarse graded slurry – rapid setting

Water – for slurry and for dilution of emulsion

SELECTION AND CONSTRAINTS

Guidelines for the selection of suitable materi-als, constraints and concerns relating to the usage and application are covered in Chapter 6, “Materials Selection, Constraints and De-sign Procedures”.

A topic that needs some special attention is the climatic conditions as outlined in Chapter 6, “Weather Limitations”.

Experience has shown that the environment can have an important effect on the performance of seals. Important factors include:

• the minimum and maximum road sur-face temperature, • rainfall pattern, and • the wind experienced during the seal op-erations.

Even under generally constant weather conditions, the road surface and air temperature will show a regular daily variation, with the minimum temperature being recorded at sunrise. The temperature measured just before starting the sealing operation and at sunrise can be used to predict the temperature condition for the day. The ideal condition for seal construction is warm and dry weather with no rain. Work should not proceed

• when rain is threatening, • when there is a strong wind blowing that could affect the spraying performance of the distributor, and • when the road surface temperature is be-low the minimum given in Chapter 6, “Sur-facing, Weather Limitations”, table headed “Road surface temperature for application of binders”.

In very hot climatic conditions, special precautionary steps must be implemented during the heat of the day, or when temperatures increase rapidly, to prevent



pickup of a freshly laid seal soon after opening to traffic or when recently placed and under traffic for a few days. If necessary, the surface can be cooled down with a water spray and/or blinding with a fine aggregate (sand, grit or even 6,7 mm) (refer work by NB Dumas1).

In the case of slurry operations, the slurry should be applied when the air temperature is at least 7°C and with the likelihood of increasing. The operation should be stopped when the air temperature is dropping and reaches 13°C. In the case of a Cape Seal, care should be taken when placing the first slurry layer during the hottest time of the day, as the coarse aggregate layer may be disturbed. If this happens, it is advisable to suspend the first slurry layer operations during the heat of the day, or when disturbance of the coarse aggregate layer becomes evident, and to restrict slurry work to the early morning and/or late afternoon, or even at night using artificial lighting. Slurry should not be applied during unsettled weather conditions unless rapid-setting or cationic emulsion is being used. M

ATERIALS

18-4

Although the embargo on winter-surfacing, during the months June, July and August may be relaxed with the approval of the Materials Engineer, it is not favoured. Such approval will only be considered when it is assured that strict control will be exercised during the sealing operations and that the special conditions applicable are adhered too.

COMPONENT CONFORMANCE CONTROL

The aspects to be controlled for each component (aggregate, binder, water, etc.) are outlined in Chapter 8, “Quality Control”, for the various types of seals as indicated by the following tables:

Prime Coat (table entitled, “Component conformance control – prime”)

1. Dumas, N.B., “The retention of bituminous surfacing

aggregate with respect of maximum road surface temperature”. Proceedings of Conference of Asphalt Pavements for Southern Africa, Victoria Falls, 1999.

Sand Seal (table entitled, “Component conformance control – sand seal”)

Chip and Spray (table entitled, “Compo-nent conformance control – chip & spray seal”)

Slurry (table entitled, “Component con-formance control – slurry for seals”)

SAMPLING The guidelines for sampling plan and procedures for the various components (binder, aggregate, water, etc.) are provided in:

Chapter 4, “Sampling Methods” for

• Processed Material (aggregate) • Bituminous Products • Water • Cement and Lime

Chapter 11, “Stockpiled Material”

TESTS The various test methods to be used with commentary on the test methods are outlined in Chapter 3, “Commentary on Test Methods”, or SABITA Manuals, as indicated by the type of control to be exercise on the various components as outlined in Chapter 8, “Quality Control” for the Component Conformance Control of the appropriate seals.

TIME SCHEDULE TO OBTAIN ACCEPTANCE

The time schedule to obtain acceptance for the appropriate use of materials is governed by the time to obtain samples for testing and the duration of specific special tests that may be required by the Materials Engineer or Project Specifications. A schedule for the duration of most of the normal tests is outlined in Chapter 3, “Time schedule for duration of testing”.

page 06 June 2008 18 Acceptance control: seals


APPLICABLE FORMS

MATERIALS

Stage Form Code Description

Sampling S-SOU-SUR-E Field Samples Of Aggregate For Surface Treatment

Testing T-DAT-SUR1-E Test Data: Aggregate For Bituminous Surfacing and Layers

T-DAT-BRB-E Bitumen - Rubber Binder: Spray/Mixing Grade: Compo-nent And Blend-ing Control

ASSESSMENT The quality of the components (aggregate, binder, water, etc.) will be determined to en-sure that the various components conform to the requirements specified for the type of seal being used.

AGGREGATE The quality and treatment of coarse aggregate, as specified in Chapter 2, shall be according to the following guidelines:

For modified binders (latex modified and/or bitumen-rubber) only grades 1 or 2 ag-gregate are acceptable.

For unmodified penetration grade binders only grades 1 or 2 are acceptable.

For unmodified emulsion binders grades 1, 2 or 3 are acceptable.

No precoating of aggregates is required for work using emulsion binders.

Precoating of aggregate is mandatory for bitumen-rubber or latex modified penetration grade bitumen binders. In special cases this may also be applicable to unmodified penetra-tion grade bitumen as authorised by the Mate-rials Engineer or Project Specifications.

BINDERS The quality and treatment of the various types of binders as specified in Chapter 2, “Standards”, must conform to the SABS specifications for unmodified binders. Modified binders must conform with the requirements in Chapter 2, “Standards” or the Project Specifications.

WATER The quality of the water and it’s compatibility with bitumen emulsion will determine the ap-propriate treatment and use thereof.



DESIGN VERIFICATION (LABORATORY)

INTRODUCTION

DESIGN VERIFICATION

18-6

Well before commencing with the placing of a seal, the design parameters for the seal, the de-termination of the most appropriate seal and the recommended applications rates or ratios shall be carried out as outlined in Chapter 6, “Materials Selection, Constraints and Design Procedures”, for the following treatments:

Prime Coat

Tack Coat

Sand Seal

Chip and Spray

Coarse Slurry

APPLICATION RATES The parameters used to determine the application rates for the applicable seals are as follows:

Chip and Spray

• Traffic factor (P) according to the heavy traffic (E 80s) and construction traffic • Climatic zone • Road surface condition, either a newly constructed layer, or an existing surfaced road/street, i.e., texture depth, cracks, etc.

• Steep gradients, climbing lanes, etc. • Average least dimension (ALD) of coarse single-sized aggregate, determined by calculation using the grading and flaki-ness index (FI) of the aggregate • Binder volatile/expansion factor (f) for each type and grade of binder • Type, hardness and durability of the aggregate

Slurry

The design and composition for the vari-ous types of slurry mixes as outlined in Chapter 6, “Materials Selection, Con-straints and Design Procedures”.

Notes The amount of active filler (cement or

lime) to be added will depends on the percent-age passing the 0,075 mm sieve of the fine ag-gregate. With a higher percentage passing, a low amount of active filler should be used and vice versa, not exceeding the limits given.

The amount of active filler will determine the setting time of the emulsion.

In the case of rapid setting coarse slurry, the type and grading of the aggregate will af-fect the emulsion modification, manufacturing and control of binder.

The compatibility of the rapid setting binder with aggregate from sources near to the project must be carried out by the supplier of the binder, after which the test data of the ag-gregate and the proposed design properties must be submitted for approval.

APPLICABLE FORMS The applicable form E-DET-SUR1-E (Deter-mination of Surface Treatment Applications) should be used. An example of a completed form is given on page 18-7. As noted in Chap-ter 6, “Selection, constraints and design proce-dures”, the results for the spray rate obtained from the TRH 3 method are evaluated against the WCPA method. This procedure will be superseded with the use of the Product De-signer Software, once available.

The design properties for coarse slurries (either slow or rapid setting) are normally given in a letter.



DESIGN VERIFICATION

Figure 18-2: Example of completed form E-DET-SUR1-E



DESIGN VERIFICATION (TRIAL SECTION)

INTRODUCTION Once the quality of the materials has been veri-fied and approved, and the recommended ap-plications rates are available, it is necessary that, before proceeding with the first trial run, the following aspects should be considered.

ROAD SURFACE CONDITIONS

DESIGN VERIFICATION

18-8

Newly constructed layers to be surfaced:

• The visual acceptance of the exposed mosaic of the base is required.

• The moisture content of the base be-fore priming (and after priming if it has been exposed to intermittent rain) must be determined and found accept-able.

Existing Surfaced Roads:

• Pavement defects, such as potholes, ruts and edge breaks, must be repaired according to the prescribed mainte-nance methods or the Project Specifi-cations.

• The surface must be cleaned by either rotary or hand brooms, air or water under pressure.

• The moisture condition of the base layer must be checked after rain spells, since moisture ingress is possi-ble due to fine cracks in the surface (which cannot be practically or eco-nomically treated), or lean, dry, or open seals which can be porous. De-pending on the moisture content, a de-lay in the operation may be necessary.

AGGREGATE Consider the following issues:

Stockpiles should be spaced at economic intervals along the road, for easy accessibility when loading of trucks, and to minimize load-

ing and travel time between stockpiles and seal site.

The sites to be used for stockpiles must be properly cleared to minimize contamination and pollution.

Each stockpile shall be properly sampled to ensure the required field samples are ob-tained and that all relevant tests are carried out to determine the quality and to establish rec-ommended application rates.

Uncoated, single-sized, coarse aggregates in stockpile may, in certain cases, be damp-ened with water to eliminate the negative ef-fect of excessive dust adhering to the aggre-gates. When using certain types and grades of binders, excessive free water on the aggregate is detrimental to the breaking, curing and ad-hesion of the binder to the aggregate.

The type of precoating fluid used to pre-coat aggregate and the application rate to en-sure uniform coating and the ageing of the coating film on the aggregates will depend on the time interval between coating and the seal operation, which in turn will determine the ef-fectiveness of the seal in the long run.

The temperature of the aggregate in the stockpile (especially when damp and after un-expected cold nights) also has an affect on the adhesion of the aggregate.

BINDER Consider the following issues:

The site location for stationary bulk tank-ers should be such as to enable easy accessibil-ity for filling the bitumen distributor and to minimize the refilling and travelling time be-tween bulk tanker and site.

The site should be level to enable correct volume measurements of binder in tankers and distributor obtained by dipstick readings.



The appropriate, specified binder, must be ordered, delivered and correctly transferred to a stationary bulk tanker reserved for that spe-cific binder. Different types and grades of bi-tumen binders are not mixable.

The particulars of the binder supplied (such as batch number, viscosity and recom-mended spray temperature) must be provided by the supplier.

In the case of modified binders, the blending process on site must be according to the prescribed procedure/method.

Only water which is compatible with the appropriate type of emulsion shall be used for dilution or with slurries (refer Chapter 2, “Ma-terials Standards, Water, Slurry and Emul-sion”).

DESIGN VERIFICATION

The recommended application rates for each type/size of aggregate, stockpile, binder type and grade, needs to be obtained.

The temperature of the binder in the dis-tributor must be according to the required spray specification.

DISTRIBUTOR The testing and spraying performance of bitu-men distributors shall be in accordance with the guidelines outlined in Chapter 7, “Con-struction Equipment Control”, and interim guidelines prepared by RPF task team (Distin and Dumas) on binder distributors2 (until re-vised TMH2 is available). In addition, the fol-lowing issues need attention:

The distributor shall be in a roadworthy condition.

The driver and/or operator shall be prop-erly trained and competent and in possession of a valid certificate of compliance.

The overall condition of the distributor shall be checked before commencement of the seal operation to confirm the condition and calibration of the dipstick, spraybar, nozzles 2. “Guidelines for calibrating a binder distributor and

procedures for checking site spray performance”, Roads Pavement Forum, SABITA, 2006.

(same type), and to check the functioning of the fifth-wheel.

The operation and opening of all nozzles should be confirmed by spraying for a few sec-onds into suitable pans. Any malfunctioning nozzles shall be replaced or adjusted to achieve the correct fan angle. The test procedure is referred to as the “bucket test”2.

The spraybar height should be checked and adjusted according to the type of nozzle fitted. For Copley nozzles, the height of the spraybar must result in a double overlap of nozzle sprays fans while for Etnyre, and most other nozzles, it should give a triple overlap.

CHIP SPREADER Consider the following issues:

The chip spreader must be in good run-ning order, cleaned and serviced, including checking of the air pressure of the pneumatic tyres.

A standby chip spreader shall be avail-able.

The chip spreader shall be required to spread the aggregate in a single layer. A trial run on a clean, unsprayed surface is recom-mended, after which the aggregate can be col-lected for re-use.

The ability of the driver to operate a self-propelled chip spreader shall be confirmed, or, in the case of spreaders fitted to the rear of the truck, the ability of the truck driver to drive at a constant reverse speed should be checked.

Only well trained and competent opera-tors are to operate the spreaders.

TRUCKS Consider the following issues:

Sufficient trucks must be available to maintain continuity in the seal operation, espe-cially where stockpiles are spaced far apart.

The volume of the fully loaded truck and the aggregate level at the top after loading



from the stockpile site must be recorded to en-sure that the correct spread rate of the aggre-gate can be calculated in m2/m3.

SLURRY MIXING PLANT

DESIGN VERIFICATION

18-10

Consider the following issues:

Stationary or mobile batch mixers must be in a good operational condition, while weigh bridges and volume indicators must be calibrated, etc.

Mobile continuous flow mixing machines must be roadworthy, and the volume or mass of hopper capacity recorded. Operational func-tions of the mixer and spreader box, must be in good condition and adjustable for various widths.

OTHER PLANT All support equipment such as a water trucks, rollers, rotary and/or hand brooms, must be available.

PROCESS AND ACCEPTANCE CONTROL SOFTWARE

For the purpose of process and acceptance con-trol of seal work (including accepted trial sec-tions), two software applications, specially de-veloped by the WCPA, are to be utilised on site. Installation of the software on site, and training in its use, is to be undertaken through prior arrangement with the Head: Pavement Technology, Materials Testing Laboratory, be-fore seal work commences. Refer also to the website www.pavementquality.org.za

The first software application is used to under-take acceptance control of the stockpiled seal aggregates, prior to their use (refer Form E-ASS-SUR-E).

The second application, WCPA Surface Seal Process Control (Seal-Pro), is used to guide and record the seal construction process, as it progresses. Before commencing with the first trial run, the approved seal design is loaded into the Seal-Pro software. The following re-

cords of each days production, are to be cap-tured into the software at the end of each day:

Binder application and aggregate spread rates.

Weather data recorded three times daily.

• Wind speed (Beaufort Scale) • Air and road surface temperatures • Cloud cover

Slurry mix designs and variations

Photographic records

TRIAL RUN OPERATION

CHIP AND SPRAY At the commencement of the seal operations a trial run is required.

The minimum road surface, air and aggregate temperature at sunrise (as well as just before the first trial run) and the temperature of the binder in the distributor must be measured and recorded.

For an efficient first trial run, a reasonable length of road section should be sprayed, which should be determined according to the volume of the aggregate in the chip spreader and/or trucks available awaiting discharge into the spreader. The length sprayed must be such that it does not exceed the length which can immediately be covered with the aggregate, in order to prevent the binder becoming chilled, or starting to break before the application of the aggregate, or acquiring a coating of dust (which will retard adhesion).

In the case of an erroneous binder spray appli-cation, it should be rejected for acceptance and receive remedial action. In the case of a single application, under spray can be corrected to obtain the correct total volume of binder re-quired by applying a second spray, either di-luted or undiluted. In the case of a minor single spray over application, as an interim remedy, it should be blinded with fine aggregate. In the case of severe bleeding, the seal must be re-moved. In the case of double binder spray ap-


http://www.pavementquality.org.za/


plication, underspraying or over spraying of the first spray (tack coat) can be corrected with the necessary adjustment in second spray ap-plication to obtain the required total volume of binder.

Care must be taken to accurately guide the dis-tributor to keep the edge of the sprayed width along the line required. Where the seal is ap-plied in more than one pull, which is usually the case when the road is resealed under traf-fic, or in the case of a wide road surface, the overlap should preferably be along the centre line, or along traffic lanes. This will assist in providing a constant transverse distribution over the width of overlap, which usually means that the overlap should be between 100 and 150 mm wide.

Each spray should be started and ended on ei-ther a paper or rubber strip, or steel plate, at least one metre wide, placed transversely over the full width of the section to be sprayed. This will minimize any uneven distribution of binder resulting from the spraybar and/or noz-zles being not properly opened and closed and leading to bleeding.

DESIGN VERIFICATION

The volume of the binder, before and after each run shall be measured and recorded, as well as the length of section and width of spraybar. The volume sprayed (in litres) and the area of the section (in m2) is then used to calculate the application rate (in ℓ/m2). The spray rate achieved on the trial run is com-pared with the recommended spray rate. Over or under spraying needs another trial run to verify the road speed only.

The WCPA Surface Seal Process Control Soft-ware (Seal-Pro) must be used, as set up spe-cifically for the project, to record the construc-tion process and the completion data.

In the case of a single coarse aggregate seal, the aggregate should be placed with shoulder to shoulder contact between particles. In the case of a double aggregate layer seal, the first aggregate layer should preferably not be placed with shoulder to shoulder contact be-tween particles, but spread slightly thinner to make provision for the second layer of aggre-gate to bridge between the larger particles of the first layer (especially in the case of a more

cubical and/or oversized aggregate particles of the second aggregate layer).

In the case of under chipping (spread too thinly), this can be immediately corrected by hand back chipping followed by rolling. In the case of uneven and/or overspreading brooming will be required after the layer of aggregate has been rolled. Under or overspreading of the first trial run, normally requires a second trial run, with the necessary adjustments to the spreader box opening and/or travelled spread. The total volume (m3) of aggregate spread divided by the area (m2 - length and width in metres) gives the spread rate in m2/m3 for the first trial run. When the trial is acceptable, it should be used for the full-scale seal operation.

SLURRY

SLURRY PLACED BY HAND SQUEEGEES Prior to placing the slurry the road surface should be dampened, particularly during hot weather. The slurry should be placed only by competent operators with good, rubber-blade squeegees.

The slurry mix should be homogenous with no instances of premature breaking of emulsion during the mixing process. The consistency of the slurry mix, immediately before pouring (in small manageable increments on to the road) should have a flow measurement of between 30 and 40 mm for slow setting fine slurry.

The embedment of the slurry layer and the fill-ing of voids between the coarse aggregate should be such that, after rolling, the aggregate should still be proud of the slurry and achieve a mosaic appearance to allow space for a sec-ond slurry layer.

The spread application for each layer section, expressed in kg/m2, is calculated by using only the total mass of fine aggregate (excluding the active filler of cement or lime), divided by the area.

The permeability (Marvil) expressed in litres per hour (ℓ/h), is determined after placement is deemed acceptable. In the case of a double layer, this should be after the rolling of the fi-nal layer. With unsatisfactory high permeabil-



ity i.e., exceeding the maximum criteria, fur-ther rolling may be required, or the road can be trafficked for three months before retesting. Refer to Figure 18-3 on page 18-13.

DESIGN VERIFICATION

18-12

SLURRY PLACED BY SPREADER BOX The road surface should be dampened before placing the slurry.

The slurry mix should be placed only by com-petent operators with additional rubber - blade squeegees available for rounding off where necessary.

The slurry mix should be homogenous with no instance of segregation or pre-mature breaking of emulsion during the continuous flow mix-ing process. The consistency of the slurry mix, shall be such that no flowing of the fresh slurry occurs due to high flow characteristics or steep gradient. For a coarse slurry this shall have a flow measurement not exceeding 10 to 20 mm.

In the case of volume batching, the theoretical mass of only the fine aggregate is obtained by compensating for unit mass and moisture cor-rections for the determination of the spread rate, expressed in kg/m2.

Rapid setting coarse slurry shall be sufficiently stable to be rolled after 45 minutes, before opening to traffic.

ACCEPTANCE OF TRIAL RUN The visually appearance after rolling, achieved application rates and permeability will dictate the acceptability or remedial actions required and whether approval to proceed with full pro-duction can be given.

APPLICABLE FORMS The following forms are applicable for the re-porting of the works on a daily basis for each section:


Evaluation

Chip and Spray

R-LOG-SUR1-E

Reporting - Pro-gress Log - Seal Work Control (Emulsion; Sand Seal; Chip Seals 6,7; 9,5; 13,2; 13,2 + Grit; 13,2 + 6,7; 19,0 + 6,7; 19,0 mm)

Slurry R-LOG-SUR2-E

Reporting - Progress Log - Slurry Seal Control



DESIGN VERIFICATION

Figure 18-3: Marvil Permeability vs In-situ Voids in Asphalts



CONSTRUCTION LOTS

PROCESS AND ACCEPTANCE CONTROL SOFTWARE

CONSTRUCTION LOTS

18-14

For the purpose of process and acceptance control of seal work, two software applications developed by the WCPA are to be utilised on site. Refer to “Design Verification (Trial Section), Process and Acceptance Control Software” for descriptions of the applicable software functionalities.

ASSESSMENT The conditions and constraints applicable to the trial run are also applicable to subsequent seal lot sections. See Chapter 8, “Quality Assurance, Surfacing Seals”. The following additional aspects are to be controlled during executing the work:

In the case of chip and spray, road sur-face, air and aggregate in stockpile tempera-tures, and the quantity of binder in the distribu-tor between each run, shall be measured and recorded. The position of the distributor (as regards to the gradient of the road) must be taken in to account during volume measure-ments before and after each run, which will have bearing on the true readings.

Samples must be taken of the binder from each batch.

Application rates must be within the tol-erances specified. If not, corrections shall be applied to the second binder spray to achieve the total binder application, where appropriate.

PAYMENT - ACCEPTANCE OR REJECTION

Binder - Sprays

See Chapter 8, “Quality Assurance, Rejection of Out-of-Tolerance Binder Sprays” for guide-lines to be applied in respect of acceptance at

reduced payment, or rejection of binder sprays, and/or Project Specifications.

Binder - Slurry

• Fine Slurry - see Project Specifications acceptance or reduced payment or rejection • Coarse Slurry - see Appendix B and/or Project Specifications for acceptance at reduced payment or rejection

APPLICABLE FORMS


Evaluation

Chip and Spray

R-LOG-SUR1-E

Reporting - Pro-gress Log - Seal Work Control (Emulsion; Sand Seal; Chip Seals 6,7; 9,5; 13,2; 13,2 + Grit; 13,2 + 6,7; 19,0 + 6,7; 19,0 mm)

Slurry R-LOG-SUR2-E Reporting - Progress Log - Slurry Seal Control

AS-BUILT DATA In the case of new construction or a double ag-gregate reseal the particulars and application rates were historically recorded on the As-Built Data Sheets (AB7).

On current projects, where the use of the WCPA acceptance (ABACUS) and process control (Seal-Pro) software is obligatory, the following A4 or A3 sized as-built reports are easily generated at the end of construction from electronic data captured throughout the project:

• Report 1 – Project Information • Report 2 – Spray and Spread Data • Report 3 – Spray Analysis (graphical)



• Report 4 – Spray Analysis (statistics) • Report 5 – Weather Data • Report 6 – Cape Seal Slurry Data • Report 7 – Cape Seal Slurry Mix De-signs • Report 8 – Project Photographs

Hardcopies of these reports, together with the electronic databases of both software applica-tions are to be submitted to the Head : Pave-ment Technology, Materials Testing Labora-tory.

CONSTRUCTION LOTS



SUPPLY ONLY - AGGREGATES

INTRODUCTION

SUPPLY ONLY AGGREGATES

18-16

It’s important that the supplier, contractor and client agree to a supply target grading, or to the normal standard specifications (after approval in the case of a non-commercial source), acceptance control procedures, rate of supply and stockpiling arrangement.

SAMPLING PLAN Chapter 4, “Field Sampling Methods, Sampling Plan of Process Materials”, covers a sampling plan from the conveyer belt, loaded truck, or from heaps off-loaded in a layer of a stockpile.

SAMPLING PROCEDURES Chapter 4, “Field Sampling Methods, Sampling of Processed Materials” covers sampling procedures from a conveyer belt, from pre-built stockpiles and of layers in stockpiles during off-loading in the layer or from truck loads. Refer also to Chapter 11, “Acceptance Control, Stockpiled Material”.

TESTS Chapter 8, “Quality Assurance, Component Conformance Control for Chip and Spray Seal and of Slurry for Seals” (table entitled “Component conformance control – sand seal”) includes a complete list of required tests. See also Appendix B: “Supply Specifications, Conventional Slow Setting Anionic Coarse Slurry and Rapid Setting Rubber Modified Coarse Slurry”.

The following tests must be carried out on each sample:

Coarse Single-Sized Aggregate

• Grading • Fines Content (-0,425 mm) and Dust

Content (-0,075 mm) • Treton on nominal 19,0 mm aggregate

• 10% FACT, ACV or AIV on nominal 13,2 mm aggregate

• Durability - MgSO4 weathering test in the case of no historical data of source

Fine Aggregate

• Grading (full sieve analysis) • Plasticity Index • Deleterious Materials - soluble salts • Methylene Blue Absorption test for

active clay minerals in the case of dust content (-0,075 mm) exceeding the limits, or for specific geological type of rock that may possess active clay minerals such as the smectite group (montmorrilites)

TIME SCHEDULE TO OBTAIN ACCEPTANCE

The time schedule to obtain acceptance for the processed and/or delivered product is governed by the supply project specification require-ments given in Appendix B and/or Chapter 3, “Commentary On Test Methods - Time Sched-ule for Duration Of Testing”.

APPLICABLE FORMS


Sampling S-SOU-SUR-E Field Samples of Aggregate For Surface Treatment

Testing T-DAT-SUR1-E Test Data - Aggre-gates For Bitumi-nous Surfacing and Layers

Evaluation E-ASS-SUR1-E Acceptance Con-trol - Surfacing - Aggregate (Nom 19,0 / 13,2 / 9,5 / 6,7mm)

E-ASS-SUR2-E Acceptance Con-trol - Surfacing - Aggregate (Fine Aggregate: Crusher dust/grit/sand)



ASSESSMENT

GRADING

SUPPLY ONLY AGGREGATES

TARGET GRADING SPECIFICATION In the case of agreement between contractor/supplier and client for material to comply according to a target grading, the assessment of each lot or stockpile shall comply with the requirements of a statistical judgement plan, utilising the actual variability of the product as determined from samples obtained in a statistically sampling approach. The judgement plan shall be in accordance with Chapter 9, “Acceptance Control, Basic Concepts”, and COLTO, “Standard Specifications For Road and Bridge Works3”, Section 8200, “Quality Control (Scheme 1).

The form E-ASS-SUR1-E shall be used to record the values obtained for grading. The values for tolerances for sieves, φ-values and rejection limits are given in Table 18-1.

Table 18-1: Tolerances, φ and Rejection Limits

Rejection Limits Sieve

Size

mm

Tolerances

%(+ or - , as

applicable)

φ Value

(%) Lower Lr Upper Lr’

19,0 5 20 LR = La - 0,9 LR’ = La’ + 0,9

13,2 5 20 LR = La - 0,9 LR’ = La’ + 0,9

9,5 5 20 LR = La - 0,8 LR’ = La’ + 0,8

6,7 5 20 LR = La - 0,8 LR’ = La’ + 0,8

4,75 4 10 LR = La - 0,8 LR’ = La’ + 0,8

2,36 4 10 LR = La - 1,0 LR’ = La’ + 1,0

0,425 3 10 LR = La - 0,8 LR’ = La’ + 0,8

0,300 3 10 LR = La - 0,8 LR’ = La’ + 0,8

0,075 1 10 LR = La - 0,4 LR’ = La’ + 0,4

Note: 1. Single φ value limit specification: in the case where

only a maximum limit (Ls’) is specified for a sieve, the ka value for single limit φ value should be used, such as the maximum for 0,425 mm and 0,075 mm for sin-gle sized aggregates.

2. Double φ value limit specification: for all other cases the kad value for a double limit φ value should be used.

3. “Standard Specifications for Road and Bridgeworks for

State Road Authorities”, Chapter 4100, COLTO 1998.

NON - TARGET GRADING SPECIFICA-TION In the case of agreement between contractor/supplier and client for material to comply with a grading specification limit such as SABS/SANS Standards, the assessment of each sieve is as for “Target Grading Specification”, no other tolerances on sieves are applicable. The φ values to be used shall be according to the grading limit specifications.

Example: for a nominal 19,0 mm aggregate (Grade 1) the specification limit of percentage passing the 19,0 mm sieve is 85 - 100%. In this case the ka single limit φ value should be used with Ls = 85%. For the 13,2 mm sieve the limit specification is 0 - 30% where in this case Ls’ = 30%, and the ka value for single limit φ value should be used.

Outliers shall be dealt with as in Chapter 9, “Acceptance Control: Basic Concepts”, and the Critical C-values for surfacing aggregates are found in Appendix C, Table C-1, “Random numbers”, and ka and kad for single and double limit are found in Table C-2, “Values of ka and kr = single limits - first submission”, or C-3, “Values of kad and krd - double limits - first submission”, respectively, for values of the first submission. In the case of an outlier, the ka or kad values for the specified φ value, as indicated in Table 18-1 for each sieve, will be for (n-1) number of the test values. The outlier should be further investigated to identify any possible problem. If no definite problem can be identified only then may the result be discarded.

In the case of non-compliance with the speci-fication, retesting of any test point is not per-missible. If decisions are in question due to the credibility of the test values, the whole lot or stockpile shall be retested with a new set of random test points.

If a lot is re-tested, the second lot of values shall be assessed against the first set of values (a minimum of 6 values for each set) to determine if they belong to the same population. Form E-ASS-COM2-E is used for the comparison between two sets of values. If there is a difference between the two sets, the



statistical data from the second set of values shall be taken as final. However, if there is no difference between the two sets, then the first set is taken as final.

In the case of non-compliance, the lot shall be rejected and the contractor or construction unit shall propose an appropriate remedial action. This remedial action shall be ap-proved by the Materials Engineer.

FLAKINESS INDEX No statistical judgement is applied in the case of flakiness. However, the mean should not exceed the maximum specified limit. In the case of not complying with specification, refer to the Materials Engineer.

S CRUSHED FACES UP

For acceptance, at least 95 percent of the parti-cles should have three or more crushed faces in the case of alluvial or colluvial aggregate.

PLY ONLY AGGREGATES

page 06 June 2008 18 Acceptance control: seals 18-18

acceptance control seals - rnis.westerncape.gov.za

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