Measurment of LBM

8/6/2019 Measurment of LBM

1/99

Base and Surface Course

500

Materials for Structures


2/99

148

Section 500 Base and Surface Course


3/99

149

Base and Surface Course Section 500

501 GENERAL REQUIREMENTS FOR BITUMINOUS PAVEMENT LAYERS

501.1 General

Bituminous pavement courses shall be made using the materials described in theSpecifications.

The use of machinery and equipment mentioned in various Clauses of these Specificationsis mandatory. Details of the machinery and equipment are available in the Manual forConstruction and Supervision of Bituminous Works. The equipment mandatory for anyparticular project shall be in accordance with the Contract Specifications for that project.

501.2 Materials

501.2.1 Binder : The binder shall be an appropriate type of bituminous materialcomplying with the relevant Indian Standard (IS), as defined in the appropriate Clauses ofthese Specifications, or as otherwise specified herein. The choice of binder shall bestipulated in the Contract or by the Engineer. Where viscosity grades of bitumen arespecified, they are referred to by a designation in accordance with IS:73. Where ModifiedBinder is specified, the provision of IS:15462 shall apply.

501.2.2. Coarse Aggregates: The coarse aggregates shall consist of crushed rock,crushed gravel or other hard material retained on the 2.36 mm sieve. They shall be clean,hard, durable, of cubical shape, free from dust and soft or friable matter, organic or otherdeleterious matter. Where the Contractors selected source of aggregates has poor affinityfor bitumen, as a condition for the approval of that source, the bitumen shall be treated withapproved anti-stripping agents, as per the manufacturers recommendations, withoutadditional payment to the Contractor. Before approval of the source, the aggregates shallbe tested for stripping.

The aggregates shall satisfy the physical requirements set forth in the individual relevant

clause for the material in question.

Where crushed gravel is proposed for use as aggregate for bituminous concrete, not lessthan 95 percent by weight of the crushed material retained on the 4.75 mm sieve shallhave at least two fractured faces. However for use in other (LBM, BM, DBM, etc.)specifications not less than 90 percent by weight of the crushed material retained on the4.75 mm sieve shall have at least two fractures faces.

501.2.3 Fine Aggregates: Fine aggregates shall consist of crushed or naturally

occurring material, or a combination of the two, passing 2.36 mm sieve and retained onthe 75 micron sieve. They shall be clean, hard, durable, dry and free from dust, and soft orfriable matter, organic or other deleterious matter. Natural sand shall not be allowed in


4/99

150


binder and wearing courses. However, natural sand upto 50 percent of the fine aggregatesmay be allowed in base courses. Fine aggregates shall have a sand equivalent not lessthan 50 when tested in accordance with the requirement of IS:2720 Part 37. The plasticityindex of the fraction passing 0.425 mm shall not exceed 4 when tested in accordance withIS:2720 Part 5.

501.2.4 Source of material : The source of all materials propose to be used on theproject by the Contractor shall be tested to the satisfaction of and receive express approvalof the Engineer. The Engineer may from time to time withdraw approval of a specificsource, or attach conditions to the existing approval. Any change in aggregate source forbituminous mixes, will require a new mix design, and laying trials, where the mix is basedon a job mix design. Stockpiles from different sources, approved or otherwise, shall be

kept separate, such that there is no contamination between one material and another.Each source submitted for approval shall contain material sufficient for at least 5 dayswork.

501.3 Mixing

Pre-mixed bituminous materials, including bituminous macadam, dense bituminousmacadam, bituminous concrete, etc. shall be prepared in a hot mix plant of adequatecapacity and capable of yielding a mix of proper and uniform quality with thoroughly coated

aggregates. Appropriate mixing temperatures are given in Table 500-15 of theseSpecifications. The difference in temperature between the binder and aggregate shouldat no time exceed 14C. In order to ensure uniform quality of the mix and better coating ofaggregates, the hot mix plant shall be calibrated from time to time. The essential featuresof the hot mix plants are given in Annexure A of IRC:27.

If a continuous mixing plant is to be used for mixing the bituminous bound macadam, theContractor must demonstrate by laboratory analysis that the cold feed combined gradingis within the grading limits specified for that bituminous bound material. In the case of a

designed job mix, the bitumen and filler content shall be derived using this combinedgrading. Further details are available in the IRC Manual for Construction and Supervisionof Bituminous Works.

501.4 Transporting

Bituminous materials shall be transported in clean insulated and covered vehicles. Anasphalt release agent, such as soap or lime water, which does not adversely affect thebituminous mixes may be applied to the interior of the vehicle to prevent sticking and tofacilitate discharge of the material.


5/99

151


501.5 Laying

501.5.1 Weather and seasonal limitations: Laying shall be suspended:

l In presence of standing water on the surface;

l When rain is imminent and during rains, fog or dust storm;

l When the base / binder course is damp;

l When the air temperature on the surface on which it is to be laid isless than 10 oC for mix with conventional bitumen as binder and isless than 15 oC for mix with modified bitumen as binder;

l When the wind speed at any temperature exceeds the 40 km per perhr at 2 m height.

501.5.2 Cleaning of surface : The surface on which the bituminous work is to belaid shall be cleaned of all loose and extraneous matter by means of a mechanical broomor any other approved equipment/method as specified in the contract. The use of a highpressure air jet from a compressor to remove dust or loose matter shall be available fulltime at the site, unless otherwise specified in the Contract.

501.5.3 Spreading : Prior to spreading the mix, the base shall be prepared by

carrying out all or some of the operations as per Clause 501.8 depending upon the siteconditions. Except in areas where paver cannot get access, bituminous materials shall bespread, leveled and tamped by an approved self-propelled paving machine preferablywith sensor. As soon as possible after arrival at site, the materials shall be suppliedcontinuously to the paver and laid without delay. The rate of delivery of material to thepaver shall be regulated to enable the paver to operate continuously. The travel rate of thepaver, and its method of operations, shall be adjusted to ensure an even and uniform flowof bituminous material across the screed, free from dragging, tearing and segregation ofthe material. In areas with restricted space (such as confined space, foot base, irregularshape and wearing thickness, approaches to expansion joints, etc.) where paver cannotbe used, the material shall be spread, raked and leveled with suitable hand tools by trainedstaff. The minimum thickness of material laid in each paver pass shall be in accordancewith the minimum values given in the relevant parts of these Specifications. When layingbinder course or wearing course approaching an expansion joint of a structure, machinelaying shall stop 300 mm short of the joint. The remainder of the pavement up to the joint,and the corresponding area beyond it, shall be laid by hand, and the joint or joint cavityshall be kept clear of surfacing material.

Bituminous material, with a temperature greater than 145C, shall not be laid or depositedon bridge deck water-proofing systems, unless precautions against heat damage havebeen approved by the Engineer.


6/99

152


501.5.4 Cleanliness and overlaying: Bituminous material shall be kept clean anduncontaminated. The only traffic permitted run on bituminous material to be overlaid shallbe that engaged in laying and compacting the next course or, where a binder course is tobe sealed or surface dressed, that engaged on such surface treatment. Should anybituminous material become contaminated, the Contractor shall make it good to thesatisfaction of the Engineer, in compliance with Clause 501.8.

Binder course material shall not remain uncovered by either the wearing course or surfacetreatment, whichever is specified in the Contract, for more than three consecutive daysafter being laid. The Engineer may extend this period, by the minimum amount of timenecessary, because of weather conditions or for any other reason. If the surface of thebase course is subjected to traffic or not covered within three days, a tack coat shall beapplied as directed by the Engineer.

501.6 Compaction

Bituminous materials shall be laid and compacted in layers, which enable the specifiedthickness, surface level, regularity requirements and compaction to be achieved.

Compaction of bituminous materials shall commence as soon as possible after laying.Compaction shall be substantially completed before the temperature falls below theminimum rolling temperatures stated in the relevant part of these Specifications. Rollingof the longitudinal joints shall be done immediately behind the paving operation. After this,rolling shall commence at the edges and progress towards the center longitudinally exceptthat on super elevated and unidirectional cambered portions, it shall progress from thelower to the upper edge parallel to the center line of the pavement. Rolling shall continueuntil all roller marks have been removed from the surface. All deficiencies in the surfaceafter laying shall be made good by the attendants behind the paver, before initial rolling iscommenced. The initial or breakdown rolling shall be done with 810 tonne dead weightsmooth-wheeled rollers. The intermediate rolling shall be done with 810 tonne deadweight or vibratory roller or with a pneumatic tyred roller of 12 to 15 tonne weight havingnine wheels, with a tyre pressure of at least 5.6 kg/sq.cm. The finish rolling shall be donewith 6 to 8 tonne smooth wheeled tandem rollers.

Where compaction is to be determined by density of cores, the requirements to prove theperformance of rollers shall apply in order to demonstrate that the specified density can beachieved. In such cases the Contractor shall nominate the plant, and the method by whichhe intends to achieve the specified level of compaction and finish at temperatures abovethe minimum specified rolling temperature. Laying trials shall then demonstrate theacceptability of the plant and method used.

Bituminous materials shall be rolled in a longitudinal direction, with the driven rolls nearestthe paver. The roller shall first compact material adjacent to joints and then work from the


7/99

153


lower to the upper side of the layer, overlapping on successive passes by at least one-third of the width of the rear roll or, in the case of a pneumatic-tyred roller, at least thenominal width of 300 mm.

In portions with super-elevated and uni-directional camber, after the edge has been rolled,the roller shall progress from the lower to the upper edge.

Rollers should move at a speed of not more than 5 km per hour. The roller shall not bepermitted to stand on pavement which has not been fully compacted, and necessaryprecautions shall be taken to prevent dropping of oil, grease, petrol or other foreign matteron the pavement either when the rollers are operating or standing. The wheels of rollersmachine shall be in good working order, to prevent the mixture from adhering to the wheels.

Only sufficient moisture to prevent adhesion between the wheels of rollers and the mixtureshould be used. Surplus water shall not be allowed to stand on the partially compactedpavement.

501.7 Joints

a) Where joints are made, the material shall be fully compacted andthe joint made flush in one of the following ways; All joints shall be cutvertical to the full thickness of the previously laid mix. All loosened

material shall be discarded and the vertical face be coated with anyviscosity grade bitumen, or cold applied emulsified bitumen. Whilespreading the material along the joint the material spread shall overlap25 mm to 50 mm on the previously laid mix beyond the vertical faceof the joint. The thickness of the loose overlap material should beapproximately a quarter more than the final compacted thickness.The overlapped mix should be dragged back to the hot lane so thatthe roller can press the small excess into the hot side of the joint toobtain a high joint density.

b) By using two or more pavers in echelon, where this is practicableand in sufficient proximity for adjacent widths to be fully compactedby continuous rolling.

All joints shall be offset at least 300 mm from parallel joints in the layer beneath or asdirected, and in a layout approved by the Engineer. Joints in the wearing course shallcoincide with either the lane edge or the lane marking, which ever is appropriate.Longitudinal joints shall not be situated in wheel track zones.

For transverse joints method a) above shall apply. Transverse joints in the successive andadjoining layers shall have a minimum offset of 2 meters.


8/99

154


501.8 Preparation of Surface

501.8.1 Scope : This work shall consist of preparing an existing granular or black-topped surface bituminous course. The work shall be performed on such widths and lengthsas shown on the drawings or as instructed by the Engineer. The existing surface shall befirm and clean, and treated with Prime or Tack coat as shown on the drawings as otherwisestated in the Contract.

501.8.2 Materials

501.8.2.1 For scarifying and re-laying the granular surface : The material usedshall be coarse aggregates salvaged from the scarification of the existing granular basecourse supplemented by fresh coarse aggregates and screenings so that aggregatesand screenings thus supplemented correspond to Clause 404: Water Bound Macadam orClause 406: Wet Mix Macadam.

501.8.2.2 For patching potholes and sealing cracks : Where the existing surfaceto be overlaid is bituminous, any existing potholes and cracks shall be repaired and sealedin accordance with Clauses 3004.2 and 3004.3, or as directed by the Engineer.

501.8.2.3 For profile corrective course : A profile corrective course for correctingthe existing pavement profile shall be laid to varying thickness as shown on the Drawings,

or as indicated in the Contract Documents. The profile corrective course shall be laid totolerances and densities as specified for wearing course in a single layer, or base course,if it is to be covered with a wearing course layer.

501.8.2.4 Profile corrective course and its application : The type of material foruse as profile corrective course shall be as shown on the drawings or as directed by theEngineer. Where it is to be laid as part of the overlay/ strengthening course, the profilecorrective course material shall be of the same specification as that of the overlay/ strengthening course. However, if provided as a separate layer, it shall be of the specification

and details given in the contract drawings.

i) Any high spots in the existing surface shall be removed by a millingmachine or other approved method, and all loose material shall beremoved to the satisfaction of the Engineer.

ii) Where the maximum thickness of profile corrective course will be notmore than 40 mm, the profile corrective course shall be constructedas an integral part of the overlay course. In other cases, the profilecorrective course shall be constructed as a separate layer, adoptingsuch construction procedures and using such equipment as approvedby the Engineer, to lay the specified type of material, to thicknessand tolerance as specified for the course to be provided.


9/99

155


501.8.3 Construction Operations

501.8.3.1 Preparing existing granular surface : Where the existing surface isgranular, all loose materials shall be removed, and the surface lightly watered where theprofile corrective course to be provided as a separate layer is also granular. Where theprofile corrective course of bituminous material is to be laid over the existing granularsurface, the latter shall, after removal of all loose material, be primed in accordance withClause 502.

The surface finish of all granular layers on which bituminous works are to be placed, shall,unless otherwise specifically instructed by the Engineer, be free from dust. All such layersmust be capable of being swept, after the removal of any non-integral loose material, bymeans of a mechanical broom, without shedding significant quantities of material and

dust removed by air jet, washing, or other means approved by the Engineer.

After cleaning the surface shall be correct to line and level, within the tolerances specifiedfor base course.

501.8.3.2 Scarifying existing bituminous surface : Where specified or shown onthe drawings, the existing bituminous layer in the specified width shall be removed withcare and without causing undue disturbance to the underlying layer, by a suitable methodapproved by the Engineer. After removal, all loose and disintegrated material, the underlying

layers which might have been disturbed should be suitable reworked and compacted toline and level. After supplementing the base material as necessary with suitable freshstone, the compacted finished surface shall be primed in accordance with Clause 502.Reusable materials shall be stacked as directed by the Engineer within 1000m of theirorigin.

501.8.3.3 Patching of potholes and sealing of cracks : Where the existing surfaceto be overlaid is bituminous, any existing potholes and cracks shall be repaired and sealedin accordance with Clauses 3004.2 and 3004.3, or as directed by the Engineer.

501.8.3.4 Laying the profile corrective course

501.8.3.4.1 Laying on granular base : After preparing the granular surface inaccordance with Clauses 501.8.3.1 and 501.8.3.2, the profile corrective course shall belaid using material as described in Clauses501.8.2.3 and 501.8.2.4, or as otherwisedescribed in the Contract, and compacted to the requirements of the particularSpecification.

501.8.3.4.2 Laying on existing bituminous surface : The existing bituminous surface

shall be prepared in accordance with Clause 501.8.3.3, and after applying a tack coatconforming to Clause 503, the bituminous profile corrective course shall be laid andcompacted to the requirements of the particular Specification.


10/99

156


501.8.3.4.3 Correction of local depressions : Where local sags or depressions occurin the existing pavement, a specific filling operation shall be instructed by the Engineer,which should be laid in accordance with Figure 500-1. Normally, the maximum layerthickness at any point should not exceed 100 mm. In placing multiple lifts, they should bearranged according to the correct method as illustrated.

For correction of camber or super-elevation of the existing carriageway, the method shownin Figure, 500-2 shall be adopted, depending on the profile of the existing carriageway.

501.8.3.5 Covering the profile corrective courses : Profile corrective courseparticularly shall be so planned that the layer shall be covered by the designed base/wearingcourse at the earliest opportunity, before opening to regular traffic.

501.8.4 Surface finish and quality control of work : The relevant provisions ofSection 900 shall apply.

501.8.5 Arrangements for traffic : During construction operations, arrangementsfor traffic shall be made in accordance with the provisions of Clause 112.

501.8.6 Environmental protection : The provisions of Clause 111 and the provisionof Appendix A to Clause 501 shall apply.

501.8.7 Measurement for payment

501.8.7.1 Potholes and cracks : The work of filling potholes shall be measuredseparately and be paid for in square metres.

The work of filling cracks by applying fog spray or emulsion slurry seal shall be measuredin square metres, for the area covered by the spray.

The work in filling cracks larger than 3 mm in width shall be measured and paid for on a

linear metre basis.

501.8.7.2 Scarifying : Scarifying the existing bituminous surface shall be measuredand paid for on a square metre basis.

501.8.7.3 Profile corrective course : Profile corrective course shall be measuredas the volume instructed and compacted in position and measured in cubic metres, or intonnage, as stipulated in the Contract. The volume shall be calculated by plotting the exactprofile of profile corrective course as required, and laid, superimposed on the existing

pavement profile. Cross-sectional areas of the profile corrective course shall be measuredat intervals as used in the design, or as determined by the Engineer, and the volume shallbe calculated using the method of end areas.


11/99

157


501.8.7.4 Prime coat : Prime coat shall be measured and paid for on a square metrebasis.

501.8.7.5 Tack coat : This is to be a provisional item, which may be used in-part ornot at all, at the Engineers direction, and is to be measured and paid for, if used, on asquare metre basis.

501.8.8 Rates

501.8.8.1 Rate for scarifying : The contract unit rate for scarifying existing bituminoussurfaces, including repairing/reworking disturbed underlying layers and removing andstacking reusable/unusable materials, shall include for but not necessarily be limited to,the cost of all labour, supply of materials needed for repair/reworking, hire charges of tools

and plant, and transportation of scarified materials.

501.8.8.2 Rate for premixed bituminous material : The contract unit rate forpremixed bituminous material shall be payment in full for carrying out the required operationsincluding full compensation for, but not necessarily limited to:

i) Making arrangements for traffic to Clause 112 except for initialtreatment to verge, shoulders and construction of diversions.

ii) Preparation of the surface to receive the material.

iii) Providing all materials to be incorporated in the work includingarrangement for stock yards, all royalties, fees, rents where necessaryand all leads and lifts.

iv) Mixing, transporting, laying and compacting the mix, as specified.

v) All labour, tools, equipment, plant including installation of hot mix plant,power supply units and all machinery, incidental to complete the workto these Specification.

vi) Carrying out the work in part widths of the road where directed.vii) Carrying out all tests for control of quality.

viii) The rate shall cover the provision of bitumen at the rate specified inthe contract, with the provision that the variation in actual percentageof bitumen used will be assessed and the payment adjustedaccordingly.

ix) The rates for premixed material are to include for all wastage in cuttingof joints etc.

x) The rates are to include for all necessary testing, mix design,transporting and testing of samples, and cores. The Contractor shallarrange to carry out all necessary testing as directed by the Engineer,


12/99

158


and all costs incurred are deemed to be included in the Contractorsrates.

xi) The cost of all plant and laying trials as specified to prove the mixing

and laying methods is deemed to be included in the Contractorsrates.

501.8.8.3 Rate for potholes and crack sealing : The rate for patching potholesshall include for breaking out, trimming edges, cleaning out, painting edges and bottomwith bitumen, and filling and compacting the excavation with the specified material. Therate should be inclusive of all plant, tools, labour and materials, transport, and disposal ofsurplus material.

The contract unit rate for sealing cracks by applying fog spray shall be inclusive of providingall materials, tools, labour and plant and carrying out the work. The contract unit rate forsealing cracks by providing emulsion slurry seal shall be as set forth in Clause 513.9.

The contract unit rate for crack sealing 3mm to 6mm cracks with straight run or otherspecified bitumen, shall be based on either a square metre basis, or linear metre of cracksas measure, as stipulated by the Contract.

The contract unit rate for cracks between 6mm and 15mm is to be measured on a linear

metre basis, and the rate is to include for all materials, tools, plant, labour, and transport.

Appendix A to Clause 501

Appendix APROTECTION OF THE ENVIRONMENT

1. General

1.1 This Appendix sets out limitations on the Contractors activitiesspecifically intended to protect the environment.

1.2 The Contractor shall take all necessary measures and precautionsand otherwise ensure that the execution of the works and allassociated operations on or off site are carried out in conformity withstatutory and regulatory environmental requirements including thoseprescribed elsewhere in these Specifications.

1.3 The Contractor shall take all measures and precautions to avoid anynuisance or disturbance arising from the execution of the Works. Thisshall wherever possible be achieved by suppression of the nuisanceat source rather than abatement of the nuisance once generated.


13/99


14/99

160


3.3 Any vehicle with an open load-carrying area used for transportingpotentially dust producing material shall have properly fitting side andtail boards. Materials having the potential to produce dust shall not

be loaded to a level higher than the side and tail boards, and shall becovered with a clean tarpaulin in good condition. The tarpaulin shallbe properly secured and extended at least 300 mm over the edgesof the side and tail boards.

3.4 In the event that the Contractor is permitted to use gravel or earthroads for haulage, he shall provide suitable measures for dustpalliation, if these are, in the opinion of the Engineer, necessary. Suchmeasures may include sprinkling water on the road surface at regularintervals.

4 Noise

4.1 The Contractor shall consider noise abutment measures in hisplanning and execution of the Works.

4.2 The Contractor shall take all necessary measures so that the operationof all mechanical equipment and construction processes on and offthe Site shall not cause any unnecessary or excessive noise, takinginto account applicable environment requirements. The Contractor

shall use all necessary measures and shall maintain all plant andsilencing equipment in good condition so as to minimize the noiseemission during construction works.

5 Control of Wastes

5.1 The Contractor shall control the disposal of all forms of wastegenerated by the construction operations and in all associatedactivities. No uncontrolled deposition or dumping shall be permitted.

Wastes to be so controlled shall include, but shall not be limited to, allforms of fuel and engine oils, all types of bitumen, cement, surplusaggregates, gravels, bituminous mixtures etc. The Contractor shallmake specific provision for the proper disposal of these and anyother waste products, conforming to local regulations and acceptableto the Engineer.

6 Emergency Response

6.1 The Contractor shall plan and provide for remedial measures to beimplemented in the event of occurrence of emergencies such asspillages of oil or bitumen or chemicals.


15/99

161


6.2 The Contractor shall provide the Engineer with a statement of themeasures he intends to implement in the event of such an emergency,which shall include a statement of how he intends to provide personneladequately trained to implement such measures.

7. Measurement

7.1 No separate measurement shall be made in respect of complianceby the Contractor with these provisions. The Contractor shall bedeemed to have made allowance for such compliance with theseprovisions in the preparation of his prices for items of work includedin the Bills of Quantities and full compensation for such compliancewill be deemed to be covered by them.

502 PRIME COAT OVER GRANULAR BASE

502.1 Scope

This work shall consist of the application of a single coat of low viscosity liquid bituminousmaterial to a porous granular surface preparatory to the superimposition of bituminoustreatment or mix.

502.2 Materials

The bituminous material to be used as primer shall be such that it can penetrate about10 mm deep into base course. Bitumen emulsion SS1 grade conforming to IS:8887/ASTMD2397 or medium curing cutback bitumen conforming to IS:2177 can be used as primer.

Quantity of SS1 grade bitumen emulsion for various types of granular surface shall be asper Table 500-1:

Table 500-1 Quantity of Bitumen Emulsion for Various Types ofGranular Surface

Type of Surface Rate of Spray (kg/sq.m)

WMM/WBM 0.71.0Mechanically lime/cement stabilized soil bases,lime cement bases 0.91.2Gravel bases, Crusher run Macadam andcrushed rock bases 1.21.5

Cutback when used as primer shall not be prepared in field. Type and quantity of cutbackbitumen for various types of granular surface shall be as per Table 500-2.


16/99

162


Table 500-2 Type and Quantity of Cutback Bitumen for Various Types ofGranular Surface

Type of Surface Type of Cutback Rate of Spray (kg/sq.m)

WMM/WBM MC 30 0.60.9Mechanicallylime/cement stabilizedsoil bases, lime cement bases MC 70 0.91.2Gravel bases, Crusher run Macadamand crushed rock bases MC 250 1.21.5

The correct quantity of primer shall be decided by the Engineer and shall be such that themaximum amount that can be absorbed by the surface without causing run-off of excessiveprimer and to achieve desired penetration of 10 mm .

502.3 Weather and Seasonal Limitations

Cutback bitumen as primer shall not be applied to a wet surface. Bitumen emulsion shallbe applied on a damp surface. Surfaces which are to receive emulsion primer should bedamp, but no free or standing water shall be present. Surface can be just wet by very lightsprinkling of water. Primer shall not be applied during a dust storm or when the weather isfoggy, rainy or windy or when the temperature in the shade is less than 10C.

502.4 Construction

502.4.1 Equipment : The primer distributor shall be a self-propelled or towed bitumenpressure sprayer equipped for spraying the material uniformly at specified rates andtemperatures. Hand spraying shall not be allowed except in small areas, inaccessible tothe distributor, or in narrow strips where primer shall be sprayed with a pressure handsprayer, or as directed by the Engineer.

502.4.2 Preparation of road surface : The surface to be primed shall be preparedin accordance with Clauses 501.8. and 902 as appropriate. Immediately prior to applyingthe primer, the surface shall be swept clean of dust and loose and other foreign particlesusing power broom or mechanical sweepers, care being taken not to disturb the interlockedaggregates.

502.4.3 Application of bituminous primer : After preparation of base as per502.4.2, the primer shall be sprayed uniformly in accordance with Clause 501. The methodfor application of the primer will depend on the type of equipment to be used, size of

nozzles, pressure at the spray bar and speed of forward movement. The Contractor shalldemonstrate at a spraying trial, that the equipment and method to be used is capable ofproducing a uniform spray, within the tolerances specified.


17/99

163


No heating or dilution of SS1 emulsion and preparation of cutback bitumen shall bepermitted at site. Temperature of cutback bitumen shall be high enough to permit the primerto be sprayed effectively.

502.4.4 Curing of primer and opening to traffic : A primed surface shall be allowedto cure for at least 24 hours or such other higher period as is found to be necessary toallow all the moisture/volatiles to evaporate before any subsequent surface treatment ormix is laid. Any unabsorbed primer shall first be blotted with an application of sand, usingthe minimum quantity possible. A primed surface shall not be opened to traffic other thanthat necessary to lay the next course.

502.4.5 Tack coat : Over the primed surface, a tack coat should be applied inaccordance with Clause 503.

502.5 Quality Control of Work

For control of the quality of materials and the works carried out, the relevant provisions ofSection 900 shall apply.

502.6 Arrangements for Traffic

During construction operations, arrangements for traffic shall be made in accordance withthe provisions of Clause 112.

502.7 Measurement for Payment

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 the requiredoperations including full compensation for all components listed in Clause 401.8 (i) to (v)and as applicable to the work specified in these Specifications. Payment shall be made

on the basis of the provision of prime coat at an application rate of quantity, unless otherwisespecified in the BOQ, at 0.6 kg per square metre, with adjustment, plus or minus, for thevariation between this amount and the actual amount approved by the Engineer after thepreliminary trials referred to in Clause 502.4.3.

503 TACK COAT

503.1 Scope

This work shall consist of the application of a single coat of low viscosity liquid bituminous

material to an existing bituminous, cement concrete or primed granular surface preparatoryto the superimposition of a bituminous mix, when specified in the Contract or instructed bythe Engineer.


18/99

164


503.2 Materials

The binder used for tack coat shall be either Cationic bitumen emulsion (RS 1) complyingwith IS 8887/ASTM D 2397 or suitable low viscosity paving bitumen of VG 10 gradeconforming to IS:73. The use of cutback bitumen RC:70 as perIS:217 shall be restricted only for sites at sub-zero temperatures or for emergencyapplications as directed by the Engineer. The type and grade of tack coat shall be asspecified in the Contract or as directed by the Engineer.

503.3 Weather and Seasonal Limitations

Bituminous material shall not be applied during a dust storm or when the weather is foggy,rainy or windy or when the temperature in the shade is less than 10C. Where the tackcoat consists of emulsion, the surface shall be slightly damp, but not wet. Where the tackcoat is of cutback bitumen, the surface shall be dry.

503.4 Construction

503.4.1 Equipment: The tack coat shall be applied by a self-propelled or towedbitumen pressure sprayer, equipped for spraying the material uniformly at a specified rate.Hand spraying shall not be permitted except in small areas, inaccessible to the distributor,or narrow strips, shall be sprayed with a pressure hand sprayer, or as directed by theEngineer.

503.4.2 Preparation of base: The surface on which the tack coat is to be appliedshall be clean and free from dust, dirt, and any extraneous material, and be otherwiseprepared in accordance with the requirements of Clauses 501.8 and 902 as appropriate.The granular or stabilized surfaces shall be primed as per Clause 502. Immediately beforethe application of the tack coat, the surface shall be swept clean with a mechanical broom,and high pressure air jet, or by other means as directed by the Engineer.

503.4.3 Application of tack coat : The application of tack coat shall be at the ratespecified in the Contract, and shall be applied uniformly. If rate of application of Tack Coatis not specified in the contract, then it shall be the rate specified in Table 500-3. Nodilution or heating at site of RS1 emulsion shall be permitted. Paving grade of bitumen ifused for tack coat shall be heated in bitumen boilers to achieve viscosity less than 2 poise.The normal range of spraying temperature for a bituminous emulsion shall be 20C to70C and for a cutback, 50C to 80C if RC-70/MC-70. Where a geosynthetic is proposedfor use, the provisions of Clauses 703.3.2 and 703.4.4 shall apply. The method ofapplication of tack coat will depend on the type of equipment to be used, size of nozzles,

pressure at the spray bar, and speed or forward movement. The Contractor shalldemonstrate at a spraying trial, that the equipment and method to be used is capable ofproducing a uniform spray, within the tolerances specified.


19/99

165


Where the material to receive an overlay is a freshly laid bituminous layer, that has notbeen subjected to traffic, or contaminated by dust, a tack coat is not mandatory where theoverlay is completed within two days.

Table 500-3 Rate of Application of Tack Coat

Type of Surface Rate of spray of emulsion Rate of spray of/cutbackKg per sq m bitumen Kg per sq m

Bituminous surfaces 0.20 0.30 0.30 0.40Granular surfaces treated 0.25 0.30 0.35 0.45with primerCement concrete pavement 0.30 0.35 0.40 0.50

503.4.4 Curing of tack coat

The tack coat shall be left to cure until all the volatiles have evaporated before anysubsequent construction is started. No plant or vehicles shall be allowed on the tack coatother than those essential for the construction.

503.5 Quality Control of Work



During the period of construction, arrangements for traffic shall be made in accordancewith the provisions of Clause 112.


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

503.8 Rate

The contract unit rate for tack coat shall be payment in full for carrying out the requiredoperations including for all components listed in Clause 401.8 (i) to (v) and as applicableto the work specified in these Specifications. The rate shall cover the provision of tack

coat, quantity unless otherwise specified in the BOQ, at 0.2 kg per square metre, with theprovision that the variance in actual quantity of bitumen used will be assessed and thepayment adjusted accordingly.


20/99

166


504 LEAN BITUMINOUS MACADAM

504.1 Scope

This work shall consist of construction of 75 mm thick single course of compacted crushedaggregates premixed with a bituminous binder on a previously prepared base to therequirements of these Specifications. This specification may be used for laying of profilecorrective course (PCC) where thickness of PCC is more than 75 mm and strengtheningof weak bases, where strengthening by granular layer is not feasible due to difficulties inscarification or due to economical reasons.

504.2 Materials

504.2.1 Bitumen : Clause 506.2.1 shall apply504.2.2 Coarse aggregate : Clause 506.2.2 shall apply

504.2.3 Fine aggregate : Clause 506.2.3 shall apply

504.2.4 Aggregate grading and binder content :

The combined grading of the coarse aggregates and fine aggregates, when tested inaccordance with IS 2386 Part 1, wet sieving method, shall conform to limits given in Table500-4. The quantity of bitumen and appropriate thickness is also given in Table 500-4.

Table 500-4 Aggregate Grading and Bitumen Content

Layer thickness 75 mm

IS Sieve size (mm) Cumulative % by weight of total aggregate passing

45 10026.5 75-10022.4 60-9511.2 30-555.6 15-352.36 4 190.075 0 5Bitumen content ** percentby mass of total mix 2.5

* Nominal maximum aggregate size is the largest specified sieve size upon which

any of the aggregate material is retained.** Corresponds to specific gravity of the Aggregate being 2.7. In case of aggregates

have specific gravity more than 2.7, bitumen content can be reduced proportionately.


21/99

167


504.2.5 The combined aggregate grading shall not vary from the lower limit on onesieve to the higher limit on the adjacent sieve to avoid gap grading. The aggregate may beproportioned and blended to produce a uniform mix complying with the requirements ofTable 500-4.

504.2.6 Proportioning of material : The aggregates shall be proportioned andblended to produce a uniform mixture complying with the requirements of Table 500-4,The binder content shall be within a tolerance of + 0.3 percent by weight of total mixturewhen individual specimens are taken for quality control tests in accordance with theprovisions of Section 900.

504.3 Construction Operation

504.3.1 Weather and seasonal limitations : The provisions of Clause 501.5.1shall apply.

504.3.2 Preparation of the base : The base on which bituminous macadam is tobe laid shall be prepared, shaped and compacted to the required profile in accordancewith Clauses 501.8 and 902.3 as appropriate, and a prime coat, shall be applied inaccordance with Clause 502 where specified, or as directed by the Engineer.

504.3.3 Tack coat : A tack coat in accordance with Clause 503 shall be applied asrequired under the Contract, or as directed by the Engineer.

504.3.4 Preparation and transportation of the mix : The provisions of Clause501.3 and 501.4 shall apply.

504.3.5 Spreading : The provisions of Clauses 501.5.3 shall apply.

504.3.6 Rolling : Compaction shall be carried out in accordance with the provisionsof Clauses 501.6 and 501.7.

Rolling shall be continued until the specified density is achieved, or where no density isspecified, until there is no further movement under the roller. The required frequency oftesting is defined in Clause 903.

504.4 Surface Finish and Quality Control of Work

The surface finish of the completed construction shall conform to the requirements of Clause902. For control of the quality of materials and the works carried out, the relevant provisionsof Section 900 shall apply.


22/99

168


504.5 Protection of the Layer

The bituminous macadam shall be covered with either the next pavement course or wearingcourse, as the case may be, within a maximum of forty-eight hours. If there is to be anydelay, the course shall be covered by a seal coat to the requirement of Clause 512 beforeopening to any traffic. The seal coat in such cases shall be considered incidental to thework and shall not be paid for separately.




Bituminous macadam shall be measured as finished work in cubic metres, or by weight inmetric tonnes, where used as regulating course, or square metres at the specified thicknessas indicated in the Contract or shown on the drawings, or as otherwise directed by theEngineer.

504.8 Rate

The contract unit rate for bituminous macadam shall be payment in full for carrying out therequired operations as specified. The rate shall include cost for, all components listed inClause 501.8.8.2.

505 DENSE GRADED BITUMINOUS MACADAM

505.1 Scope

This clause specified the construction of Dense Bituminous Macadam, (DBM), for usemainly, but not exclusively, in base/binder and profile corrective courses. The work shallconsist of construction in a single or multiple layers of DBM on a previously prepared baseor sub-base. The thickness of a single layer shall be 50 mm to 100 mm.

505.2 Materials

505.2.1 Bitumen : The bitumen for dense bituminous macadam shall comply withthe Indian Standard Specification for viscosity graded bitumen, IS:73 modified bitumen

complying with IS:15462 or as otherwise specified in the Contract. Guidelines for selectionof viscosity graded bitumen and modified bitumen are given in Table 500-5 and Table500-6 respectively.


23/99

169


The type and grade of modified bitumen to be used shall be specified in the Contract. Theuse of modified bitumen is recommended for very heavy traffic roads in very hot climate.

Both the highest daily mean air temperature and the lowest daily mean air temperaturesmentioned in Tables 500-5 and 500-6 can be obtained for the weather station nearest tothe project site from the Indian Meteorological Organization (IMO). The IMO has data ondaily mean high temperature for all 365 days in a year for all weather stations based onhistorical records of the last 30-40 or more years. This daily mean high temperature on aspecific day is the same as daily normal high temperature for that day as usually reportedin some newspapers. The highest of the 365 daily mean high air temperatures (whichusually occurs on some day in May or June) is used in Tables 500-5 and 500-6. Likewise,the lowest daily mean air temperature (which usually occurs on some day in January) canalso be obtained from the IMO. Since these are mean temperatures based on the averageof 30-40 years data, these temperatures are significantly lower than the absolute maximumtemperatures, which may have occurred in a specific year.

Table 500-5 Selection Criteria for Viscosity-graded (VG) Paving BitumensBased on Climatic Conditions

Highest Daily Mean Air Temperature, C

Lowest Daily Mean Less than 20C 20 to 30C More than 30C

Air Temperature, CMore than 10C VG-10 VG-20 VG-30

-10C or lower VG-10 VG-10 VG-20

Table 500-6 Selection Criteria for Grade of Modified Bitumen

Lowest Daily Mean Highest Daily Mean Air Temperature, CAir Temperature, C Less than 20C 20 to 30C More than 30C

Grade of Modified Bitumen

More than -10C PMB/NRMB 120 PMB/NRMB 70 PMB/NRMB 40CRMB 50 CRMB 55 CRMB 60

-10C or lower PMB/NRMB 40 PMB/NRMB 120 PMB/NRMB 70CRMB 50 CRMB 55 CRMB 50

PMB = Polymer modified bitumenNRMB= Natural rubber modified bitumenCRMB= Crumb rubber modified bitumen

505.2.2 Coarse aggregates : The coarse aggregates shall consist of crushed rock,crushed gravel or other hard material retained on 2.36 mm sieve. They shall be clean,


24/99

170


hard, durable, of cubical shape, free from dust and soft or friable matter, organic or otherdeleterious substances. Where the Contractors selected source of aggregates havepoor affinity for bitumen, as a condition for the approval of that source, the bitumen shall betreated with an approved anti-stripping agent, as per the manufacturers recommendations,without additional payment to the Contractor. Before approval of the source, the aggregatesshall be tested for stripping. The aggregates shall satisfy the requirements specified inTable 500-7.

Where crushed gravel is proposed for use as aggregate, not less than 90 percent byweight of the crushed material retained on the 4.75 mm sieve shall have at least two fracturedfaces.

Table 500-7 Physical Requirements for Coarse Aggregate for Dense GradedBituminous Macadam

Property Test Specification

Cleanliness (dust) Grain size analysis Max 5% passing IS 2386 Part I0.075 mm sieve

Particle shape Flakiness Index Max 15%longation Index Max 20% IS 2386 Part I

Strength Los Angeles Abrasion Value Max 35%

Aggregate Impact Value Max 27% IS 2386 Part IVDurability Soundness either :

Sodium Sulphate or Max 12%Magnesium Sulphate Max 18% IS 2386 Part V

Water Absorption Water Absorption Max 2% IS 2386 Part III

Stripping Coating and Stripping of Bitumen MinimumAggregate Mixtures retained coating IS 6241

95%

Water Sensitivity Retained Tensile Strength* Min 80% ASHTO 283

* If the minimum retained tensile test strength falls below 80 percent, use of antistripping agent is recommended to meet the requirement.

505.2.3 Fine aggregates : Fine aggregates shall consist of crushed or naturallyoccurring mineral material, or a combination of the two, passing the 2.36 mm sieve andretained on the 75 micron sieve. Natural sand shall not be allowed in binder courses.

However, natural sand upto 50 percent of the fine aggregate may be allowed in basecourses. They shall be clean, hard, durable, dry and free from dust, and soft or friablematter, organic or other deleterious matter. The fine aggregate shall have a sand equivalent


25/99

171


value of not less than 50 when tested in accordance with the requirement of IS:2720 (Part37). The plasticity index of the fraction passing the 0.425 mm sieve shall not exceed 4,when tested in accordance with IS: 2720 (Part 5).

505.2.4 Filter : Filter shall consist of finely divided mineral matter such as rock dust,hydrated lime or cement approved by the Engineer. The use of hydrated lime should beencouraged because of its very good anti-stripping and antioxidant properties. The fillershall be graded within the limits indicated in Table 500-8.

Table 500-8 Grading Requirements for Mineral Filler

IS sieve (mm) Cumulative per cent passing by weight oftotal aggregate

0.6 1000.3 95 100

0.075 85 100

The filler shall be free from organic impurities and have a Plasticity Index not greaterthan 4. The Plasticity Index requirement shall not apply if filler is cement or lime. Wherethe aggregates fail to meet the requirements of the water sensitivity test in Table 500-7,then 2 per cent by total weight of aggregate, of hydrated lime shall be used and percentageof fine aggregate reduced accordingly.

505.2.5 Aggregate grading and binder content : When tested in accordancewith IS:2386 Part 1 (wet sieving method), the combined grading of the coarse and fineaggregates and added filler for the particular mixture shall fall within the limits given inTable 500-9 for dense bituminous macadam grading 1 or 2 as specified in the Contract.To avoid gap grading, the combined aggregate gradation shall not vary from the lowerlimit on one sieve to higher limit on the adjacent sieve. The quantity of bitumen, andappropriate thickness, are also indicated for each mixture type.

505.3 Mix Design

Bitumen content indicated in the Table 500-9 is the minimum. The exact bitumen contentrequired shall be determined following the Marshall mix design procedure contained inAsphalt Institute Manual MS2.

The fines to bitumen F/B ratio by weight of total mix shall range from 0.6 to 1.2.

505.3.1 Requirements for the mix : Apart from conformity with the grading andquality requirements for individual ingredients, the mixture shall meet the requirements setout in Table 500-10.


26/99

172


Table 500-9 Composition of Dense Graded Bituminous MacadamPavement Layers

Grading 1 2Nominal aggregate size* 37.5 mm 26.5 mmLayer thickness 75 100 mm 50 75 mmIS Sieve 1 (mm) Cumulative % by weight of total aggregate passing45 10037.5 95 100 10026.5 63-93 90-10019 - 71-9513.2 55-75 56-809.5 - -4.75 38-54 38-542.36 28-42 38-541.18 - -0.6 - -0.3 7 21 7-210.15 - -0.075 2 8 7-21Bitumen content % by massof total mix ** Min 4.0 Min 4.5

Notes: * The nominal maximum particle size is the largest specified sieve size upon whichany of the aggregate is retained.

** Corresponds to specific gravity of aggregates being 2.7. In case aggregate havespecific gravity more than 2.7, the bitumen content can be reduced proportionately.Further the region where highest daily mean air temperature is 30 oC or lower andlowest daily air temperature is 10 oC or lower, the bitumen content may be increasedby 0.5 percent

Table 500-10 Requirements for Dense Graded Bituminous Macadam

Properties Viscosity Graded Modified bitumen Test MethodBitumen Hot climate Cold climate

Compaction level 75 blows on each face of the specimenMinimum stability 9.0 12.0 10.0 AASHTO T245(kN at 60C)Marshall flow (mm) 2 4 2.5 4 3.5 5 AASHTO T245Marshall Quotient 2 5 2.5 - 5 MS -2 and% air voids 3 5 ASTM D2041

% voids filled withbitumen 65 75Coating of aggregateparticle 95% minimum IS 6241Tensile Strength ratio 80% Minimum AASHTO T 283% voids in Mineral Minimum per cent voids in mineral aggregate (VMA) are set out inaggregate VMA Table 500-11.


27/99

173


Table 500-11 Minimum Per Cent Voids In Mineral Aggregate (Vma)

Nominal Maximum Minimum VMA, Per cent Related to Design Air voids, Percent 2

Particle Size 1 (mm) 3.0 4.0 5.026.5 11.0 12.0 13.037.5 10.0 11.0 12.0

Notes: 1) The normal maximum particle size is one size larger than the first sieve to retainmore than 10 percent.

2) Interpolate minimum voids in the mineral aggregate (VMA) for design airvoids values between those listed.

505.3.2 Binder content : The binder content shall be optimized to achieve therequirements of the mix set out in Table 500-10. The Marshall method for determining theoptimum binder content shall be adopted as described in the asphalt institute ManualMS-2.

Where maximum size of the aggregate is more than 26.5 mm, the modified Marshallmethod using 150 mm diameter specimen described in MS-2 and ASTM D 5581 shall beused. This method requires modified equipment and procedures. When the modifiedMarshall test is used, the specified minimum stability values in Table 500-10 shall bemultiplied by 2.25, and the minimum flow shall be 3 mm.

505.3.3 Job mix formula : The Contractor shall submit to the Engineer for approvalat least 20 days before the start the work, the job mix formula proposed for use in theworks, together with the following details:

i) Source and location of all materials;

ii) Proportions of all materials expressed as follows where each isapplicable:

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

by weight of total aggregate including mineral filler;

iii) A single definite percentage passing each sieve for the mixedaggregate;

iv) The individual gradings of the individual aggregate fraction, and theproportion of each in the combined grading;

v) The results of mix design such as maximum specific gravity of loosemix (Gmm), compacted specimen densities, Marshall stability,flow,air voids, VMA, VFB and related graphs and test results of AASHTOT 283 Moisture susceptibility test;


28/99

174


vi) Where the mixer is a batch mixer, the individual weights of each typeof aggregate, and binder per batch;

vii) Test results of physical characteristics of aggregates to be used;

viii) Mixing temperature and compacting temperature.While establishing the job mix formula, the Contractor shall ensure that it is based on acorrect and truly representative sample of the materials that will actually be used in thework and that the mixture and its different ingredients satisfy the physical and strengthrequirements of these Specifications.

Approval of the job mix formula shall be based on independent testing by the Engineer forwhich samples of all ingredients of the mix shall be furnished by the Contractor as requiredby the Engineer.

The approved job mix formula shall remain effective unless and until a revised Job MixFormula is approved. Should a change in the source of materials be proposed, a new jobmix formula shall be forwarded by the Contractor to the Engineer for approval before theplacing of the material.

505.3.4 Plant trials permissible variation in job mix formula : Once thelaboratory job mix formula is approved, the Contractor shall carry out plant trials to establishthat the plant can produce a uniform mix conforming to the approved job mix formula. The

permissible variations of the individual percentages of the various ingredients in the actual mixfrom the job mix formula to be used shall be within the limits as specified inTable 500-12 and shall remain within the gradation band. These variations are intended toapply to individual specimens taken for quality control tests in accordance with Section 900.

Table 500-12 Permissible Variations from the Job Mix Formula

Description Base/binder Course

Aggregate passing 19 mm sieve or larger + 8%Aggregate passing 13.2 mm, 9.5 mm + 7%Aggregate passing 4.75 mm + 6%Aggregate passing 2.36 mm, 1.18 mm, 0.6 mm + 5%Aggregate passing 0.3 mm, 0.15 mm + 4%Aggregate passing 0.075 mm + 2%Binder content + 0.3%Mixing temperature + 10C

505.3.5 Laying trials : Once the plant trials have been successfully completed andapproved, the Contractor shall carry out laying trials, to demonstrate that the proposed mix


29/99

175


can be successfully laid, and compacted all in accordance with Clause 501. The layingtrial shall be carried out on a suitable area which is not to form part of the works, unlessspecifically approved in writing by the Engineer. The area of the laying trials shall be aminimum of 100 sq.m of construction similar to that of the project road, and it shall be in allrespects, particularly compaction, the same as the project construction, on which thebituminous material is to be laid.

The Contractor shall previously inform the Engineer of the proposed method for laying andcompacting the material. The plant trials shall then establish if the proposed laying plant,compaction plant, and methodology is capable of producing satisfactory results. Thedensity of the finished paving layer shall be determined by taking cores, no sooner than 24hours after laying, or by other approved method. The compacted layers of Dense Graded

Bituminous Macadam (DBM) shall have a minimum field density equal to or more than92% of the average theoretical maximum specific gravity (Gmm) obtained on the day ofcompaction in accordance with ASTM D2041

Once the laying trials have been approved, the same plant and methodology shall beapplied to the laying of the material on the project, and no variation of either shall beacceptable, unless approved in writing by the Engineer, who may at his discretion requirefurther laying trials.

505.4 Construction Operations


505.4.2 Preparation of base : The base on which Dense Graded BituminousMaterial is to be laid shall be prepared in accordance with Clause 501 and 902 asappropriate, or as directed by the Engineer. The surface shall be thoroughly swept cleanby a mechanical broom, and the dust removed by compressed air. In locations where

mechanical broom cannot get access, other approved methods shall be used as directedby the Engineer.

505.4.3 Geosynthetics : Where Geosynthetics are specified in the Contract, thisshall be in accordance with the requirements stated in Clause 703.

505.4.4 Stress absorbing layer : Where a stress absorbing layer is specified inthe Contract, this shall be applied in accordance with the requirements of Clause 517.

505.4.5 Prime coat : Where the material on which the dense bituminous macadamis to be laid is other than a bitumen bound layer, a prime coat shall be applied, as specified,in accordance with the provisions of Clause 502, or as directed by the Engineer.


30/99

176


505.4.6 Tack coat : Where the material on which the dense bituminous macadamis to be laid is either bitumen bound layer or primed granular layer, tack coat shall beapplied, as specified, in accordance with the provisions of Clause 503, or as directed bythe Engineer.

505.4.7 Mixing and transportation of the mix : The provisions as specified inClauses 501.3 and 501.4 shall apply. Table 500-15 gives the mixing, laying and rollingtemperature for dense mixes using viscosity graded bitumen. In case of modified bitumen,the temperature of mixing and compaction shall be higher than the mix with viscosity gradedbitumen. The exact temperature depends upon the type and amount of modifier used andshall be adopted as per the recommendations of the manufacturer. In order to have uniformquality, the plant shall be calibrated from time to time.

505.4.8 Spreading : The provisions of Clauses 501.5.3 and 501.5.4 shall apply.

505.4.9 Rolling : The general provisions of Clauses 501.6 and 501.7 shall apply,as modified by the approved laying trials. The compaction process shall be carried out bythe same plant, and using the same method, as approved in the laying trials, which may bevaried only with the express approval of the Engineer in writing.

505.5 Opening to Traffic

It shall be ensured that the traffic is not allowed without the express approval of the Engineerin writing, on the surface until the paved mat has cooled below 60 0C in its entire depth.


The surface finish of the completed construction shall conform to the requirements ofClause 902. All materials and workmanship shall comply with the provisions set out inSection 900 of these Specifications.




Dense Graded Bituminous Materials shall be measured as finished work either in cubicmetres, tonnes or by the square metre at a specified thickness as detailed in the Contractdrawings, or documents, or as otherwise directed by the Engineer.

505.9 Rate

The contract unit rate for Dense Graded Bituminous Macadam shall be payment in full forcarrying out all the required operations as specified and shall include, but not necessarily


31/99

177


limited to all components listed in Clause 501.8.8.2. The rate shall include the provision ofbitumen, at 4 percent and 4.5 percent by weight of the total mixture for grading 1 andgrading 2 respectively.

The variation in actual percentage of bitumen used will be assessed and the paymentadjusted plus or minus accordingly.

506 BITUMINOUS MACADAM

506.1 Scope

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

or in multiple courses of compacted crushed aggregates premixed with a bituminous binderon a previously prepared base to the requirements of these Specifications. Bituminousmacadam is more open graded than the dense graded bituminous materials described inClauses 508 and 505. Since the bituminous macadam is an open-graded mixture, thereis a potential that it may trap water or moisture vapour within the pavement system.Therefore, adjacent layer should have proper drainage quality to prevent moisture-induceddamage to the BM.

506.2 Materials

505.2.1 Bitumen

The bitumen shall be viscosity graded paving bitumen complying with Indian StandardSpecification for paving bitumen, IS:73. The grade of bitumen to be used would dependupon the climatic conditions and the traffic. Guidelines for selection of viscosity grade ofpaving grade bitumen are given in Table 500-5.

506.2.2 Coarse aggregates

The coarse aggregates shall consist of crushed rock, crushed gravel or other hard materialretained on 2.36 mm sieve . It shall be clean, hard, durable and cubical shape, free fromdust and soft organic and other deleterious substances. The aggregate shall satisfy thephysical requirements specified in Table 500-13. Where crushed gravel is proposed foruse as aggregate, not less than 90 percent by weight of the crushed material retained on4.75 mm sieve shall have at least two fractured faces resulting from crushing operation.

Before approval of the source, the aggregates shall be tested for stripping. Where theContractors selected source of aggregates have poor affinity for bitumen, as a condition


32/99

178


for the approval of that source, the bitumen shall be treated with approved anti-strippingagents, as per the manufacturers recommendations, without additional payment.

Table 500-13 Physical Properties of Coarse Aggregate

Property Test Requirement Test method

Cleanliness Grain size analysis Max. 5% passing IS 2386 Part I0.075 micron

Particle shape Flakiness Index Max. 16% IS 2386 Part IElongation Index Max 24%

Strength Los Angeles Abrasion Value Max. 40% IS 2386 Part IV

Aggregate Impact Value Max. 30% IS 2386 Part IV

Soundness (Sodium or Magnesium), 5 cycles

Durability Sodium Sulphate Max. 12% IS 2386 Part V

Magnesium Sulphate Max. 18% IS 2386 Part V

Water absorption Water absorption Max. 2% IS 2386 Part III

Stripping Coating and Stripping of Min. Retained IS 6241Bitumen Aggregate Coating 95%

Water sensitivity Retained Tensile strength* Min 80% ASHTO 283

* If the minimum retained tensile strength falls below 80 percent, use of anti strippingagent is recommended to meet the minimum requirements.

506.2.3 Fine aggregates

Fine aggregates shall consist of crushed or naturally occurring mineral material, or acombination of two, passing 2.36 mm sieve and retained on 75-micron sieve. It shall beclean, hard, durable, free from dust and soft organic and other deleterious substances.The amount of rounded, natural sand in the total fine aggregate shall be limited to10 percent if the BM is used within 100 mm from the road surface and to 50 percent if theBM is used more than 100 mm below the road surface.

506.2.4 Aggregate grading and binder content

The combined grading of the coarse aggregates and fine aggregates, when tested inaccordance with IS:2386 Part 1, wet sieving method, shall conform to limits given in


33/99


34/99

180


506.2.6 Proportioning of material : The aggregates shall be proportioned andblended to produce a uniform mix complying with the requirements of Table 500-14. Thebinder content shall be within a tolerance of + 0.3 percent by weight of total mixture whenindividual specimens are taken for quality control tests in accordance with the provisionsof Section 900.

506.3 Construction Operation


506.3.2 Preparation of the base : The base on which bituminous macadam is tobe laid shall be prepared, shaped and compacted to the required profile in accordancewith Clauses 501.8 and 902.3 as appropriate, and a prime coat, shall be applied inaccordance with Clause 502 where specified, or as directed by the Engineer.

506.3.3 Tack coat : A tack coat in accordance with Clause 503 shall be applied asrequired under the Contract or as directed by the Engineer.

506.3.4 Preparation and transportation of the mix : The provisions ofClause 501.3 and 501.4 shall apply.

506.3.5 Spreading : The provisions of Clauses 501.5.3 shall apply.

Table 500-15 Mixing, Laying and Rolling Temparatures for Bituminous Mixes(Degree Celcius)

Bitumen Bitumen Aggregate Mixed Laying *RollingViscosity Temperature Temperature Material Temperature TemperatureGrade TemperatureVG-40 160-170 160-175 160-170 150 Min 100 Min

VG-30 150-165 150-170 150-165 140 Min 90 MinVG-20 145-165 145-170 145-165 135 Min 85 Min

VG-10 140-160 140-165 140-160 130 Min 80 Min

* Rolling must be completed before the mat cools to these minimum temperatures.

506.3.6 Rolling : Compaction shall be carried out in accordance with the provisionsof Clauses 501.6 and 501.7.

Rolling shall be continued until the specified density is achieved, or where no density isspecified, until there is no further movement under the roller. The required frequency oftesting is defined in Clause 903.


35/99


36/99

182


507.2 Materials

507.2.1 Bitumen : The bitumen shall be paving bitumen of viscosity grade VG 30 orVG 20, as specified in the Contract, conforming to IS:73.

507.2.2 Sand : The sand shall be clean, naturally occurring or blended material freefrom any deleterious substances, dry and well graded within the limits given inTable 500-16 and with other physical properties conforming to the requirements of this Table.

Table 500-16 Sand Grading and Physical Requirements

Sieve Size(mm) Cumulative percentage by weight of totalaggregate passing

9.5 1004.75 85 1002.36 80 1001.18 70 980.60 55 950.30 30 750.15 10 40

0.075 4 10Plasticity Index (%) 6 max.

Sand equivalent (IS:2720, Part 37) 30 min.Los Angeles Abrasion Value 40 max.

(IS:2386, Part 4)

Note: Maximum thickness for sand asphalt is 80 mm.

507.2.3 Filler : When required, filler shall consist of finely divided mineral mattersuch as rock dust, hydrated lime or cement as approved by the Engineer. The filler shallconform to Clause 505.2.4.

507.3 Mix Design

507.3.1 Requirements for the mixture : Apart from conformity with the gradingand quality requirements for individual ingredients, the mixture shall meet the requirementsset out in Table 500-17.

507.3.2 Binder content : The binder content shall be optimized to achieve therequirements of the mix set out in Table 500-17. The Marshall method for determining theoptimum binder content shall be adopted as described in the Asphalt Institute Manual MS-2.


37/99

183


Table 500-17 Requirements for Sand Asphalt Base Course

Parameter Requirement

Minimum stability (kN at 60C) 2.0Minimum flow (mm) 2Compaction level (Number of blows) 2 x 75Percent air voids 35Percent voids in mineral aggregate (VMA) 16 min.Percent voids filled with bitumen (VFB) 65-75

507.3.3 Job mix formula : The Contractor shall develop the job mix formulaproposed for use in the works and submit it to the Engineer for approval together with the

following details :

i) Source and location of all materials;

ii) Proportions of all materials expressed as follows where each isapplicable:

a) Binder, as percentage by weight of total mixture;

b) Sand/Mineral filler as percentage by weight of total aggregateincluding mineral filler;

iii) A single definite percentage passing each sieve for the mixedaggregate;

iv) The results of tests enumerated in Table 500-17 as obtained by theContractor;

v) Test results of physical characteristics of aggregates to be used;

vi) Mixing temperature and compacting temperature.

While working out the job mix formula, the Contractor shall ensure that it is based on acorrect and truly representative sample of the materials that will actually be used in thework and that the mixture and its different ingredients satisfy the physical and strengthrequirements of these Specifications.

Approval of the job mix formula shall be based on independent testing by the Engineer forwhich joint samples of all ingredients of the mix shall be furnished by the Contractor asrequired by the former.

The approved job mix formula shall remain effective unless and until modified by theEngineer. Should a change in the source of materials be proposed, a new job mix formulashall be established by the Contractor and approved by the Engineer before actually usingthe materials.


38/99

184


507.3.4 Permissible variation from job mix formula : The Contractor shall producea uniform mix conforming to the approved job mix formula, subject to the permissiblevariations of the individual percentages of the various ingredients in the actual mix fromthe job mix formula to be used, within the limits as specified in Table 500-12, with thecondition that the gradation after the variation remains within the gradation envelop. Thesevariations are intended to apply to individual specimens taken for quality control tests inaccordance with Section 900.


507.4.1 Weather and seasonal limitations : Clause 501.5.1 shall apply.

507.4.2 Preparation of base : The surface on which Sand Asphalt BasecourseMaterial is to be laid shall be prepared, shaped and graded in the profile required for theparticular layer in accordance with Clause 501 and 902 as appropriate or as directed bythe Engineer. The surface shall be thoroughly swept clean free from dust and foreignmatter using a mechanical brush, and the dust blown off by compressed air. In confinedlocations where mechanical plant cannot get access, other methods shall be used asapproved by the Engineer. A prime coat, where specified, shall be applied in accordancewith Clause 502 or as directed by the Engineer.

507.4.3 Tack coat : A tack coat over the base shall be applied in accordance withClause 503, or otherwise as directed by the Engineer.

507.4.4 Preparation and transportation of the mixture : The provisions of Clause501.3 and 501.4 shall apply.

507.4.5 Spreading : The provisions of Clauses 501.5.2 to 501.5.4 shall apply. Mixingmust be accomplished at the lowest temperatures and in the shortest time that will producea mixture with complete coating of the aggregate and at a suitable temperature to ensure

proper compaction. Guidance for mixing and compaction temperature for the particularbitumen may be taken from Table 500-15 and shall correspond to a viscosity of 2 Poise(0.2 Pa.s) and 3 poise (0.3 Pa.s) respectively, based on the original (unaged) bitumenproperties.

507.4.6 Rolling : Clause 501.6 shall apply. Generally the initial or breakdown rollingshall be done with 8-10 tonne deadweight smooth-wheeled rollers. The intermediate rollingshall be done with 810 tonne deadweight or vibratory rollers or with a pneumatic tyredroller of 12-15 tonne weight having a tyre pressure of at least 5.6 kg/sq.cm. The finishrolling shall be done with 810 tonne deadweight smooth wheeled tandem rollers. Theexact pattern of rolling shall be established at the laying trials.


39/99

185



It shall be ensured that the traffic is not allowed without the express approval of the Engineerin writing, on the surface until the paved mat has cooled below 60 0C in its entire depth.


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





Sand Asphalt Base course materials shall be measured as finished work, for the areacovered, in cubic metres, metric tonnes, or in square metres, at a specified thickness, as

stated in the Contract.The variation from the actual percentage of bitumen approved by the Engineer and usedwill be assessed and the rate adjusted, plus or minus, using the rate for bitumen in the Billof Quantities.

508 BITUMINOUS CONCRETE

508.1 Scope

This work shall consist of construction of Bituminous Concrete, for use in wearing andprofile corrective courses. This work shall consist of construction in a single layer ofbituminous concrete on a previously prepared bituminous bound surface. A single layershall be 25mm/40 mm/50 mm thick.

508.2 Materials

508.2.1 Bitumen : The bitumen shall conform to Clause 505.2.1.

508.2.2 Coarse aggregates : The coarse aggregates shall be generally as specifiedin Clause 505.2.2, except that the aggregates shall satisfy the physical requirements of


40/99

186


Table 500-18 and where crushed gravel is proposed for use as aggregate, not less than95 percent by weight of the crushed material retained on the 4.75 mm sieve shall have atleast two fractured faces.

.Table 500-18 Physical Requirements for Coarse Aggregate forBituminous Concrete

Property Test Specification

Cleanliness (dust) Grain size analysis Max 5% passing IS:2386 Part I0.075 mm sieve

Particle shape Flakiness Index Max 15% IS:2386 Part IElongetion index Max 20%

Strength Los Angeles Abrasion Value Max 30%Aggregate Impact Value Max 24% IS:2386 Part IV

Durability Soundness either :Sodium Sulphate or Max 12% IS:2386 Part VMagnesium Sulphate Max 18%

Polishing Polished stone value Min 55 IS:2386 Part IV

Water Absorption Water Absorption Max 2% IS:2386 Part III

Stripping Coating and Stripping Minimum retainedof Bitumen Aggregate coating 95% IS:6241Mix

Water Sensitivity Retained Tensile Strength* Min 80% AASHTO 283

* If the minimum retained tensile test strength falls below 80 percent, use of antistripping agent is recommended to meet the requirement.

508.2.3 Fine aggregates: The fine aggregates shall be all as specified inClause 505.2.3.

508.2.4 Filler: Filler shall be as specified in Clause 505.2.4.

508.2.5 Aggregate grading and binder content: When tested in accordance withIS:2386 Part 1 (Wet grading method), the combined grading of the coarse and fine

aggregates and added filler shall fall within the limits shown in Table 500-19 for grading1 or 2, as specified in the Contract.


41/99

187


Table 500-19 Composition of Bituminous Concrete Pavement Layers

Grading 1 2

Nominal aggregate size* 19mm 13.2mmLayer thickness 50 mm 25/40 mmIS Sieve 1 (mm) Cumulative % by weight of total aggregate passing4537.526.5 10019 79-100 10013.2 59-79 79-100

9.5 52-72 70-884.75 35-55 53-712.36 28-44 42-581.18 20-34 34-480.6 15-27 26-380.3 10-20 18-280.15 5-13 12-200.075 2-8 4-10Bitumen content % 5.2 5.4by mass of total mix

Notes: * The nominal maximum particle size is the largest specified sieve size up onwhich any of the aggregate is retained.

** Corresponds to specific gravity of aggregate being 2.7. In case aggregatehave specific gravity more than 2.7, the bitumen content can be reducedproportionately. Further the region where highest daily mean air temperatureis 30 oC or lower and lowest daily air temperature is 10 oC or lower, the bitumencontent may be increased by 0.5 percent

508.3 Mix Design

508.3.1 Requirements for the mix : Clause 505.3.1 shall apply.

508.3.2 Binder content : Clause 505.3.2 shall apply.

508.3.3 Job mix formula: Clause 505.3.3 shall apply.

508.3.4 Plant trials permissible variation in job mix formula: The requirementsfor plant trials shall be as specified in Clause 505.3.4, and permissible limits for variationas given in Table 500-20.


42/99

188


Table 500-20 Permissible Variations from the Job Mix Formula

Description Bituminous concrete

Aggregate passing 19 mm sieve or larger + 7%Aggregate passing 13.2 mm, 9.5 mm + 6%Aggregate passing 4.75 mm + 5%Aggregate passing 2.36 mm, 1.18 mm, 0.6 mm + 4%Aggregate passing 0.3 mm, 0.15 mm + 3%Aggregate passing 0.075 mm + 1.5%Binder content + 0.3%Mixing temperature + 10C

508.3.5 Laying trials : The requirements for laying trials shall be as specified inClause 505.3.5. The compacted layers of bituminous concrete (BC) shall have a minimumfield density equal to or more than 92 percent of the average theoretical maximum specificgravity (Gmm) obtained on the day of compaction in accordance with ASTM D2041.


508.4.1 Weather and seasonal limitations : The provisions of Clause 501.5.1

shall apply.

508.4.2 Preparation of base : The surface on which the bituminous concrete is tobe laid shall be prepared in accordance with Clauses 501 and 902 as appropriate, or asdirected by the Engineer. The surface shall be thoroughly swept clean by mechanicalbroom and dust removed by compressed air. In locations where a mechanical broomcannot get access, other approved methods shall be used as directed by the Engineer.

508.4.3 Geosynthetics: Where Geosynthetics are specified in the Contract, thisshall be in accordance with the requirements stated in Clause 703.

508.4.4 Stress absorbing layer : Where a stress absorbing layer is specified inthe Contract, this shall be applied in accordance with the requirements of Clause 517.

508.4.5 Tack coat : The provisions as specified in Clause 505.4.5 shall apply.

508.4.6 Mixing and transportation of the mix : The provisions as specified inClauses 501.3, 501.4 and 505.4.7 shall apply.

508.4.7 Spreading : The general provisions of Clauses 501.6 and 501.7 shall apply,as modified by the approved laying trials.


43/99

189


508.4.8 Rolling : The general provisions of Clauses 501.6 and 501.7 shall apply,as modified by the approved laying trials.

508.5 Opening to Traffic : Provisions in Clause 505.5 shall apply.

508.6 Surface Finish and Quality Control

The surface finish of the completed construction shall conform to the requirements ofClause 902. All materials and workmanship shall comply with the provisions set out inSection 900 of these Specifications.




The measurement shall be as specified in Clause 505.8.

508.9 Rate

The contract unit rate shall be all as specified in Clause 505.9, except that the rate shallinclude the provision of bitumen at 5.2 percent and 5.4 percent for grading 1 andgrading 2, by weight of total mix respectively. The variation in actual percentage of bitumenused will be assessed and the payment adjusted plus and minus accordingly.

509 CLOSE-GRADED PREMIX SURFACING/MIXED SEAL SURFACING

509.1 Scope

509.1.1 This work shall consist of the preparation, laying and compaction of a close-graded premix surfacing material of 20 mm thickness composed of graded aggregatespremixed with a bituminous binder on a previously prepared surface, in accordance withthe requirements of these Specifications, to serve as a wearing course.

509.1.2 Close graded premix surfacing shall be of Type A or Type B as specified inthe Contract documents. Type A grading is recommended for use in areas having rainfallmore than 150 cm per year. In other areas Type B grading may be used.

509.2 Materials

509.2.1 Binder : The provisions of Clause 511.1.2.1 shall apply.


44/99

190


509.2.2 Coarse aggregates : The provisions of Clause 511.1.2.2 shall apply.

509.2.3 Fine aggregates : The fine aggregates shall consist of crushed rock quarrysands, natural gravel/sand or a mixture of both. These shall be clean, hard, durable, un-coated, mineral particles, dry; and free from injurious, soft or flaky particles and organic ordeleterious substances.

509.2.4. Aggregate gradation : The coarse and fine aggregates shall be so gradedor combined as to conform to one or the other gradings given in Table 500-21, as specifiedin the contract.

Table 500-21 Aggregate Gradation

IS Sieve Designation Cumulative percent by weight of total aggregate passing

(mm) Type A Type B13.2 mm - 10011.2 mm 100 88 1005.6 mm 52 88 31 522.8 mm 14 38 5 250.090 mm 0 5 0 -5

509.2.5 Proportioning of materials : The total quantity of aggregates used forType A or B close-graded premix surfacing shall be 0.27 cubic metre per square metrearea. The quantity of binder used for premixing in terms of straight-run bitumen shall be22.0 kg and 19.0 kg per 10 square metre area for Type A and Type B surfacing respectively.


The provisions of Clause 511.1.3.1 through 511.1.3.5 shall apply.


Traffic may be allowed after completion of the final rolling when the mix has cooled down tothe surrounding temperature. Excessive traffic speeds should not be permitted.


The surface finish of construction shall conform to the requirements of Clause 902. Forcontrol on the quality of materials and the works carried out, the relevant provisions ofSection 900 shall apply.

509.6 Arrangements for TrafficDuring the period of construction, arrangements for traffic shall be in accordance with theprovisions of Clause 112.


45/99

191



Close-graded premix surfacing, Type A or B shall be measured as finished work, for thearea specified to be covered, in square metres at a specified thickness. The area will bethe net area covered, and all allowances for wastage and cutting of joints shall be deemedto be included in the rate.

509.8 Rate

The contract unit rate for close-graded premix surfacing, Type A or B shall be payment infull for carrying out the required operations including full compensation for all componentslisted in Clause 501.8.8.2.

510 SURFACE DRESSING

510.1 Scope

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 on a previously prepared,base, followed by a cover of s

Measurment of LBM

Documents

Transcript of Measurment of LBM