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TENTATIVE SPECIFICATIONFOR

BUILT-UP SPRAY GROUT

Published by

THE INDIAN ROADS CONGRESS

Jamnagar House, ShahjahanRoad,New Deihi-ilOOll

1979

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IRC: 47-1972

TENTATIVE SPECIFICATIONFOR

BUILT-UP SPRAY GROUT

Published by

THE INDIAN ROADS CONGRESS

Jamnagar House,ShabjahanRoad,New Delhi 110011

1979

PriceRs.24(Plus packaging&postage)

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IRC: 47-1972

First published: 1973

Reprinted: March 1979

Reprinted: September, 1998

(Right ofPublication ando/ Translation areresersed)

Printed at SagasPrinters&Publishers, NewDelhi

(500 copies)

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TENTATIVE SPECIFICATION FOR BUILT-UP

SPRAY GROUT

1. INTRODUCTION

This standard was prepared by the Bituminous PavementsCommittee in their meeting held on the 8th September 1971. Later itwas approved by the Specifications and Standards Committee andthen by the Executive Committee. Finally it was approved bythe Council in their 79th meeting held at Gandhinagar on the25th November, 1972. Para 5.10 has, however, been modifiedto bring in conformity withIRC Special Publication 1 1 Handbookof Quality Control for Construction ofRoads & Runways (FirstRevision).

2 , SCOPE

This specification is intended as an alternative to conventional

water bound macadam, where water may bescarceor constructionmay otherwisebe difficult such as when strengthening of an existingroad is involved which cannot be closed totraffic. Built-up spraygrout could also be adopted when machinery is not available forbituminous macadam, thoughit will notbe as strong as the latter.

3. DESCRIPTION

Built-upspray grout shall consistofa two-layercomposite con-

struction ofcompacted crushed coarse aggregates with applicationofbituminous binder after eachlayerfor bonding, finishing with keyaggregatesat the top of second layerso as to yield a thickness notexceeding75 mm. Construction in more than two layers is notrecommended,

It is an open-graded construction suitable as baseor bindercourse but should notbeutilised as a wearing course.

4. MATERIALS

4.1. Binder

4.1.1. The binder shall be one ofthe following:

(i) a straight-run bitumen of suitable penetration gradecomplying with IS: 73;

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(ii) a road tarofsuitable grade conforming to IS: 215; or

(iii) an approved cutback.

4.1.2. The grades of binder to be used would dependonclimatic conditions. The suggested binders, apart from approvedcutback, are straight-run bitumen80100, 60/70 or 30/40; and roadtar R.T. 4 or R.T. 5 .

4.2. Aggregates

4.2.1. Generalrequirements: The aggregates shall consist ofcrushed stone,crushed slag, crushed gravel(shingle) or other aggre-gate as specified having clean, strong, durable and fairly cubical

fragments, free from disintegrated pieces, salt, alkali, vegetablematter, (lust and adherent coatings.

4.2.2. Physicalrequirements: The coarse and key aggregatesshall satisfy the requirements given inTable 1 .

TAaLE I

Property ValueB as e course Binder course

Method ofTest

(1) Abrasionvalue, usingLos Angelesmachine

orAggregate impact value

(2) Flakinessindex

(3) Stripping Value

(4) Water absorption (exceptin case ofslag)

(5) Soundness: Loss withsodium sulphateS cycics(in case of slag only)

(6) Unitweight of bulkden-

sity (incase ofslag only)

Max, 50% Max, 40%

Max,40% Max. 30%

Max. 25%

Max.25%

Max. 1%

Max. 12%

Mm. 1120Kgper m8

IS: 2386 (Part IV)

do

IS: 2386 (Part I)

IS: 6241

IS: 2386 (Part Ill)

IS: 2386 (Part V)

IS: 2386 (PartIII)

4.2.3. Grading of aggregates: The coarse and key aggregatesbr built-up spray grout shall conform to the gradings giveninTable2.

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TABLE 2

Percent Passing,Sieve Size (15:460) Coarse Aggregate Key Aggregate

50 mm 10025 mm 3570

20 mm 10012.5 mm 015 35704.75 mm 015

2.36 mm 05 05

5 , CONSTRUCTION

5.1. Weather and Seasonal Limitations

Built-up spraygrout shall notbe constructed whenthe atmos-pherictemperaturein shade is below l6~Cnor whenthe pavement isdamp,or the weather is foggy or rainy or a dust storm is on.

5.2. Equipment

All equipment necessaryfor proper construction shallbe on the

siteofwork in good condition.

5.3. Preparation ofBase

Theunderlyingcourse on which built-up spray grout is tohelaid shall be prepared, shaped and conditioned toa uniform gradeand section as specified. Any depressions or pot-holes shall beproperlymade up and thoroughly compacted sufficiently in advance.

It is important that the surface be dry and thoroughly cleanedbefore start ofconstruction. As such the surface shallbe swept freeofcaked earth and other foreign matter, cleaned withhard brushes,

then withsofter brushes and finally by blowing with sacks or gunnybags to removethe finedust.

Ifthe base tobe covered is anoldblack top surface, it shall beswept clean and free ofsand, dirt, dust and othe,r loose delete~ious

foreign matterand bedry.if the baseto be treated consists of stabilised soil or porous

aggregates, a suitable bituminous primer, vide IRC : 161965Tentative Specificationfor Priming ofBase Course with BituminousPrimes shall be applied and cured before the constructioncommences.

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5.4. Tack Coat

The binder shallbe heated to the appropriate temperature asspecified and applied uniformly tothe base at the rate specified in

Table 3 preferably with a sprayer. The tackcoatshall be appliedjustahead ofthe spreadingofcoarse aggregates.

TABLE 3

Type of base Quantity per 10 m1 ofroad surface

a, On a water bound macadamsurface~ 7.5 kg.l0 kg.

h. On an existing black topsurface 6 kg. 8 kg.

5.5. Spreading and Compacting the First Layer of CoarseAggregates

5.5.1. Spreading: The coarse aggregates shall be spread andhand packed (with suitable edge protection) at the rateof 0.5 ma per10 m2 to auniform depth true to the required alignment and profile.A testing template cutto the camber of the finished pavement shallbe used to obtain uniformityofthe crown,

Thespreading shall be carried no further in advance of therolling and other operations that can be completed in one average

dayswork. Segregated aggregates or aggregates mixed with earth orother foreign substances shalt be removed and replaced with cleangraded aggregates.

5.5.2. Rolling: After spreading, the coarse aggregates shall becompactedto fullwidth by rolling with either three wheel powerroller of 8 to 10 tonnes capacity or an equivalent vibratory roller.Therollingshall begin from edges progressinggradually towards thecentreparallel to the centre line of the road, uniformly lapping eachpreceding rear wheel track by one thirdwidth. On superelevatedportions, rolling shall commence from the lower edge of thepavementprogressing gradually towardsthe upper edge.

After the roller has passed onceover the whole area, the surfaceshall bechecked witha camber template and a 3 metre straight edge.

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The surface shall notvary more than 12 mm from the template orstraight edge. All surface irregularities exceeding the above limitshallbe corrected by removing or adding aggregates as required.

Rolling shallbe discontinued before the voids are closed tosuch an extent as to prevent free and uniform penetration of thebitumen.

5.6. First Application of Binder

After the first layerofcoarse aggregates has been roiled andchecked, the binder heated toa temperature appropriate to its typeandgrade shallbe applied uniformlyover the surface preferablywiththe help ofmechanical sprayers. The quantity of binder shall be

12.5 kg. to 1 5.0 kg. per 1 0 ni~.Before applying the binder, the aggre-gates in the spread layershall besurfacedryto fulldcpth,

5.7. Spreading and Compacting Second Layer ofCoarseAggregates

Immediately, after application of binder on first layer as perpara 5.6, coarse aggregatesat the rateof 0.5 ni

t per 10 m2 shall be

spread for the second layerand compacted as described in para 5.5.

5.8. Second Application of Binder

After compacting the second layer of coarse aggregates, thebindershall be applied at the rateof 12.5 kg. to 15.0 kg. per 10 m2as detailed in para 5.6.

5.9. Application of Key Aggregate

Immediately, after the second application of binder, key aggre-gales at the rate of0.13 m3 per 10 ni2 shallbe spread uniformly byapproved manual means or preferably with the help of mechanicalgritters so as to cover the surfacecompletely.

As soon as the key aggregatesare spread, theseshall be rolledfully in accordance with para 5.5.2. While rolling is in progress,additional key aggregates may be spread by hand as necessary tomake up irregularities. Rolling shall continue until all aggregate

particles are firmly embedded in the hinder and present a uniformclosed surface.

5.10. SurfaceFinish

The surface evenness of the completed course in longitudinal

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and transverse directions shallbe within the followingtolerances:

~)Max.permissible variation:12 mm and maximum

~ number of undulations

exceeding 10 mm in any300 metre length not to

J exceed 30

Max. permissible varia-ftion: 8 mm

The longitudinal profile shallbe checked with a 3 metrelong

straight edge at the middleofeach traffic lanealong a line parallelto the centre line of the road. The transverse profile shallbechecked withaseries of three camber boards at intervals of 10metre. Fordetailed guidance in this respect, reference may bemade to IRC Special Publication 1 1 Handbook of Quality Controlfor Construction ofRoads and Runways (First Revision).

5.11. Opening to Traffic

As the built-up spray grout is an open-graded construction,thewearing course must be applied beforeopening it totraffic. Inspecialcircumstances, however, the Engineer-in-charge may openthe roadto limited traffic provided the speed ofvehicles isrestricted to 16kmper hour.

(a) Longitudinal profilewhentested with a 3-metrestraight edge

(b) Cross profile whencheck-ed with a cambertemplate

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