FRC ~48~1~)72

TENTATIVE SPECIFICATIONFOR

BITUMINOUS SURFACEDRESSING USING PRECOATED

AGGREGATES

THE INDIAN ROADS CONGRESS1990

JRC:48-1972

TENTATIVE SPECIFICATIONFOR

BITUMINOUS SURFACEDRESSING USING PRECOATED

AGGREGATES

PublishedbyTHE INDIAN ROADS CONGRESSJMmnzgarHouse,ShabjahanRoad.

New D.1h14100111990

PriceR~L~.~4(plus Postage& Packing)

JRC 48-1972

First published:1973Reprinted:February1980Reprinted:June1990

(Rights ofPublication and ofTranslationarernerve4)

Printedat SagerPrlntn& Publishers,NewDelhi (1000copies)

IRC: 48-1972

1, INTRODUCTION

This standard was prepared by the Bituminous PavementsCommittee(personnel givenbelow) in their meeting held on the8th September1971. Later it was approved by the Specificationsand StandardsCommitteeand thenby the Executive Committee,Finally it was approvedby the Council in their 79thmeetingheld atGandhinagaron the 25th November,1972.

Sujan Singh .. ConvenorProf.CO. Swarninathan .. Member-Secretary

MEMBERS

S. MumtazAll Mt. MalyaN. Arnanullab C.B.L. MathurILU. Bijiani TM, PeshorlM.K. Chatterjee Mahabir PrasadAX. Gupte Capt.P. RaghavanS Islam SatishPrasadMB Jayawant Brig. GobindarSlughS.L. Kathuria 0. SivasankaranKI Krlshan

It. Col. S,S. SundaramLU. Makhijani DR. Upadhaya

The Director General (Road!Dlrnt)& Addl. Secretaryto theGovt. of Indl~,

This specificationmaybe adoptedin lieu of the conventionalsurfacedressing,in situationswherebetteradhesionis requiredbet-weenthe aggregatesandbinder both during construction and laterin service.

The technique is basically the same as conventionalsurfacedressingexceptthat asmall quantity of binder is usedfor precoating

TENTATIVE SPECIFICATION FOR BiTUMINOUSSURFACE DRESSING USING PRECOATED AGGREGATES

2. SCOPE

—(Ex.~officlo)

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lltC: 48-1972

the aggregates. However, it is quite different from premixconstructions.

3. DESCRIPTION

The work coveredby this specification consistsof applicationof either a single or two coatsof surfacedressingovera previouslypreparedbase,eachcoat consistingof a single applicationof bitumi-nousmaterial followed by precoatedcovermaterialof the size givenin para4.2.3.

4. MATERiALS

4.!. Binder: The bindershall be oneof the following

(I) a straight-run bitumen of suitable penetrationgradecomplyingwith IS : 73;

(ii) a roadtar of suitablegradecomplyingwith IS 215; or

(iii) a cutbackbitumenof suitableviscosity complyingwith IS:

2L7 or IS 454 or otherapprovedcutback.The grade of binder to be usedwould dependipon the climate

conditions,The suggestedbindersare straight-runbitumen 80/100,road tar grade RT-3/ RT-4 or approved cutbacks.

4,2. Cover Material

4.2.1. The cover material shall consist of crushed stone,crushedslag,crushedgravel (shingle)or othercrushed aggregateasspecifiedhavingclean,strong,durableand fairly cubical fragments,free of disintegratedpieces,salt, alkali, vegetable matter, dust andadherent coatings. In casecrushed gravel is not available atreasonablecost, roundedgravel (shingle)or water borneshinglemaybe used.

The aggregatesshallpreferablybe hydrophobicin nature andof low porosity.

4.2.2. PhysIcal requirements: The aggregatesshalt satisfythe physical requirementsgiven in Table I,

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IR.C 48-1972

Value Methodof Test

(I) Abrasion value,using LosAngelesmachine

orAggregate impact value

(2) Flakiness index

(3) St ripping value

(4) Waterabsorption(exceptin case of slag)

(5) Soundness Loss withsodium sulphate—S cycles(in case of slag only)

(6) Unit weight or bulkdensity (in case of slagonly)

Max. 35% iS 2386 (Part IV)

Max. 30% —do—

Max, 25% IS 2386 (Part 1)

Max. 25% IS 6241

Max. 1% IS 2386(Part 111)

Max. 12% IS 2386 (Part V)

Mm. 1120 kg 15: 2386 (Part 111)perm’

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4.2.3. Size The size of aggregates to be used shall dependon ~rl~etl~erthe treatment is for the first coat or second or renewalcoat and shall be as indicated in Table 2.

TABLE 2. SIZE REQUIREMENTS OFAGGREGATES

Notes. (i) Thesievesare asper IS 460(ii) Vt is essential to screen the aggregatesthrough proper size sieves

to ensure the size stipulated in the specification.

TABLE I

Property

pe of conntionJ Nozt 0t

t~~reg~es

(1) First coat 13.2mm Passing through 224mmsieveandretainedonIl .2 mm sieve.

(2) Second orrenewal coat 11.2mm Passing through 13.2mm

sieve andretained on6.7 mm sieve.

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1RC 48-1972

4.2.4. Precoating: The aggregatesshall be precoatedwith0.75 to I per centof its weight of binder and shallnot be precoatedsimultaneously with the painting operation. The precoatedaggregatesshall be allowed to curefor at leastone week so thatthese become non-sticky and can be broadcasteasily from thebaskets like normal aggregatesand could even be stored for afew monthsif so required.

The aggregatesfree of dustor fine particlesshallbe preheatedto 60~Cfor precoatingexceptfor cutbackssuch as RC-3 and thenmixed with binder heated to its application temperature. Theaggregateandbinder should be thoroughly mixed in a mixer ofapprovedtypetill all the aggregatesareuniformly coated.

5. CONSTRUCTION

5.1. Weatherand SeasonalLimitations

Preferably,thesurfacedressingwork shall be carriedout onlywhenthe atmospherictemperaturein shade is 16CC or above. If,however,the work hasto bedoneduring when the temperature islower, suitableprecautionssuchasusingappropriatecutbacks,shallbe taken. Normally no bituminousmaterial Shallbe n.pplied whenthe surfaceor cover material is damp,whenthe weatheris foggy orrainy, or duringduststorm.

5.2. Arrangementsfor TrafficThe road so treatedshall beclosed in length equalto a day’s

work. Suitablediversionsshall be constructedto divert the traffic.Adequatearrangementsof barriers, flags, traffic signsfor diversion,red warninglights etc. shallbe madefor the conveniónceandsafetyof traffic. All diversionsshall be kept wateredsoas to prevent dustgettingon to the cleanedor paintedsurface.

5.3. Preparation of Road SurfaceThe underlying courseon which surface dressing is to be laid

shall be prepared, shapedand conditioned to a uniform grade andsectionas specified. Any depressionsor pot-holes shall be properlymade up and thoroughly compacted sufficiently in advance. Thedefectiveparts shall be cleanly cut and patched with new material.Where the existing surface shows signsof “fatting up”1 such portionsshall be suitably rectified.

It is important the surface be dry and thoroughly, cleaned ofcaked earth and other foreign matter immediately before applying

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IR.C: 48-1972’

the binder. The surfaceshall be cleaned first with hard brushes,thenwith softerbrushes,andfinally by blowing with sacksor gunnybags in order toremovethe fine dust. If the baseto be treatedcon-sistsof stabilisedsoil or porous aggregates,a suitable bituminousprimer vide IRC:16*, shall beappliedandcured before the cons-tructionis started.

If the baseto be coveredis an oldblacktopsurface,it shall beswept cleanof Sand,dirt, dustand othCr loose deleteriousforeignmatter,by meansof mechanical brooms and blowers if available,supplementedby handbrooms,or by meansof wire brushes,smallpicks, hand brooms etc., and shall be dry. All pot-holes anddepressionsshallbefilled up with asuitablepremix rammed properlyandbrought to shape.

5.4. FIrst Coat

5.4.1. Applicationof binder: After the underlying surfacehas been preparedas specified in para 4.3, the binder heated toappropriatetemperatureshall be sprayeduniformly over the drysurface preferably using mechanical sprayers. The rate ofapplicationshall be 15 to 17.5kg. per 10 m2 for straightrun bitumenand 17.5 to 20 kg. per 10 m2 for cutbacks and road tars.Excessivedeposits of bituminous materialuponthe road surfacecausedby stoppingor starting the sprayer or by leakage,shall beimmediately removed.

5.4.2. Application of cover material : Immediately afterapplication of binder, precoated~covermaterial of 13.2mm size(see para 3.2.3.) at the rate of0.14 to 0.15 m~per 10 m5, shallbe spreaduniformly by handor preferablyby meansof a mechanicalgrit spreader orso asto cover the surfacecompletely.

Beforecommencingrolling, the surfaceshall be broomed witha view to ensureuniform coverageof aggregates.

5.4.3. Rolling: Right after the applicationof’ cover material,the entiresurfa~eshallbe rolled with a 6to 8 tonnesmoothwheeledroller. Rolling shall commenceatthe edgesandprogresstowards thecentreexceptin superelevatedportionswhereit shallproceedfrom theinner edgeto the outer. Eachpass of the roller shalluniformlyoverlapnot lessthanone third of the track made in the preceding

*TentatfyeSpecificationfor Priming of Base Course with BituminousPrimers.

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IRC : 48-1972

pass. While rolling is in progress,additional aggregatesshall bespreadby hand in whateverquantitiesrequired to make up irregu-Iarities. Rolling shall be continueduntil all aggregateparticlesarefirmly embeddedin the binderandpresenta uniform closedsurface.Excessiverolling resultingin the crushing of aggregatesshall beavoided.

5.5. Secondor RenewalCoat

5.5.1. Time interval : The second coat of surfacedressingwherespecified,shallbe applied either immediately after the firstcoator soonafterdependingon the conditionsat site and type ofbinder used. Whereroadtar is the binder,the second coat shouldbecompletedright after thefirst coat.

5.5.2. Application of binder : Wherethe binder applicationis for renewalcoat, the receiving surfaceshallbe prepared,shapedandconditionedto specifiedgradeand camberas describedin para5.3.

The binder heatedto a temperatureappropriateto its applica-tion shall be sprayeduniformly on the clean dry surface,preferablyusingmechanical sprayers. The rate of applicationshall be 9.4 to10.8 kg per 10 ni’ in the caseof straight-run bitumen and 10.8 to13.2 kg per TOm2 in the caseof cutbacksandroad tar.

5.5.3. Application of cover material : Immediately afterapplicationof the binder, precoatedcover materialof 1 l.2~mmsize(seepara4.2.3),at the rateof 0.09 to 0.1:1 m5 per 10 mt, shall bespreaduniformly by handor preferablyby meansof a mechanicalgrit spreaderso as to cover the surfacecompletely.

Before startingrolling, the surfaceshall be broomed with aview to ensureuniform spreadingof aggregates.

5.5.4. RoIling : Soonafter the aggregateis spreaduniformly,rolling with a6 to 8 tonneroad roller shall be done in the samemanneras describedin para5.4.3.

5.6. Surface Finish

Surface evennessof the completedwork in longitudinalandtransversedirections shall be within the tolerancesindicated inTable 3.

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IRC 48-1972

TABLE 3. PERMIrrED TOLERANCES OF SURFACE EvE~nss~oaSURFACE DRESSING

Type of baseon whichsurfacedressingisapplied

Longitudinal profile Cross profile

*

Max. permissiblevariation from speci-fled profile when mea-sured with a cambertemplate

Max. permissibleundu-lation whenmeasuredwith a 3-metrestraightedge

(I) WBM. penetra-tion macadam orbuilt-up spray grout

(2) Bituminousmacadam

12mm

10 mm

8 mm

6 mm

The longitudinal profile shall be checkedwith a 3-metre longstraight edge, at the middle of each trafficlane along a line parallelto the centreline of theroad. Thetransverseprofile shall becheckedwith aseriesof threecamberboardsat intervals of10 metres.

It is emphasisedthat surface dressingby itself cannot removeany undulationspresentin the baseor the surface on which it isapplied. It is, therefore, essentialthat all operationsof rectifications tomeet the requirementsset out abovebe carried out on the receivingsurface before the work of surface dressing is begun.

5.7. Opening to TrafficWhen straight-run bitumen or road tar is used asthe binder,

the finished surfacemay be thrown open to traffic on the followingday, but if in specialcircumstances,theroad is required to be openedto traffic immediately after rolling, the speed of traffic shall berestricted to 16 km per hour till the following day.

Where cutback bitumen is used, the finished surface shall beclosed to traffic until it is sufficiently cured to hold the coveraggre-gatesin place. Control of traffic shall be ensured by appropriatedevices,suchas barricadesandpostingof watchmen.

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