IRC : 14-1977

RECOMMENDED PRACTICE FOR

2 CM THICK BITUMEN AND TAR CARPETS

(SECOND REVISION)

THE INDIAN ROADS CONGRESS 1988

JRC : 14-1977

RECOMMENDED PRACTICE FOR

2 CM THICK BITUMEN AND TAR CARPETS

(SECOND REVISION)

Published by THE INDIAN ROADS CONGRESS

Jauinagar House, Sbahjabao Road, New Delhi-110 011

1988 Price Rs 24/­

[PJus poataae & packina)

IRC : 14-1977

First published in 1963 First Revision October, 1970 Second Revision July, 1977 Reprinted: February, t987

(Incorporates amended sieve sizes) Reprinted : August, 1988 Reprinted : February, 2000

[Rights of Publication tmd of Translation ar1 reHrYed)

Printed at DEE KAY PRINTERS, New Delhi-ll0015 (500 copies)

me: I4-J9n

RECOMMENDED PRACTICE FOR 2 CM THICK BITUMEN Al'\D TAR CARPETS

INTRODUCTION

This Standard was originally printed in 1963. The revised standard which is in metric tJnits after being approved by tne Bituminous Pavements Committee was processed by the Specifi­cations & Standards Committee and then approved by the Executive Committee before it was approved by the Council of the Indian Roads Congress in their meeting held at Darjeeling on the 5th and 6th April, 1970 for being issued as the finalised standard of the Indian Roads Congress.

The present revised standard besides containing a few minor amendments approved by the Bituminous Pavements Committee also contains revised tolerances for surface evenness as approved by the Council of the 1ndian Roads Congress in their 87th meeting held at Madras on the 27th August 1976 and incorporated in the lRC Special Publication 16 .. Surface Evenness of Highway Pave­ments" .

SCOPE

Thjs is a recommended practice for laying 2 em thick bitumen and ta r carpels. The type and grade of binder is left to the discretion of the Engineer-in-charge, so a s to tc iu conformity with cl imatic, traffic ar.d terrain condilions and based on past successful practices.

A. 2 CM THICK BITUMEN CARPET

A .l. Materials

A .1.1. Binder : The bir.dcr shall be one of the following :

(i} a straight run bitumen of suitable penetration grade compl)ing with IS: 73-1961 ;

(ii) a cutback bitumen of suitable viscosity complying with IS: 217-1961 or IS: 454- 1961 or other approved cutback.

A .1.1. Coarse a~gregates : The aggregates shall consist of angular fragments and te clean, hard , tough, durable and of uniform quality throughout . They shall be crushed rock, gravel, river shingle or slag and should be free of elongated or flaky pieces,

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IRC : 14-1977

soft and disintegrated material, vegetable or other deleterious matter. The aggregates shall also satisfy the following properties:

Property 1 Value I Method of test

l. Abrasion value, using Los Angeles machine max. 35"o IS: 2386 (Pan IV)

or Aggregate impact value

2. Flakiness index 3. Stripping value 4. Water absorption (except in case of slags)

max 30% max. 30% max. 25% max 2%

-do-IS: 2336 (Part I) IS: 6Z41 IS: 2386 (Part HI)

S. Soundness: Loss with sod1um sulphate-5 cycles (m case of slag only)

6. Unit weight or bulk dens1ty (in case of slag only)

mlX. t:Z0~ IS: 2386 ( Part V) min. 1120 leg IS: 2386{Part Ill) per m"~

Uncrusbed and rounded river gravel or shingle can also be used but the quantity of binder would be different tn their ca:;e from that given under para A.2. Where such rounded aggregates are used, it may be necessary to add sufficient quantity of coars~ sand and an appropriate quantity of bot bitumen to make the mixture suitable, for wbtch purpose such a mix will h:1ve to be designed for binder content depending on individual cases.

A.I.3. Fine aggregates or sand : The fine aggregates or sand shall consist of clean, hard, durable, uncoated, coarse dry particles, and be free from injurious amounts of dust, soft or flaky particles or organic matter or other deleterious substances.

A.2. Quantities of Materials Requjred A.2.1. Aggregates A.2.1.1. For carpet

(a) Coarse aggregates-13.2 mm size; passing IS 22.4 rom square mesh , retained on IS I 1.2 mm square mesh

(b) Coarse aggregates-11.2 mm size; passing IS 13.2 mm square mesh. retained on IS 5.6 mm square mesh

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Per 10m2 of road surface

0.18m"'

0.09 m3

0.21 m3

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A.2.1.2. For seal coat

(a) Low rainfa/f areas (undeJ 150 em per year)

Medium coarse sand (fineness modulus of more tlian 2.5) or fine grit passing lS Sieve No. 1.70 mm and retained on IS Sieve No. 180 microns

(b) *High rainfall areas (over 150 em per year)

Coarse agg:regates-6.7 D1l!?- size; passing IS 11.2 mm square mesb, retained on lS Sieve 2.8 mm mesh

A.2.2. Binder

A.2.2.1. For tack coat

(a) On a water-bound macadam surface

(b) On an existing black top surface

IRC: 14-1977

0.06 m1

0.09 m'

Per 10m2 of road surface

7.3 to 9.8 kg

4.9 to 7.3 kg

Note . For emulsions complying with IS: 3117-1965, the same quantities as given above may be used. · In case the exist­ing black top surface .is extremely rich in binder, or fatty the tack coat can be eliminated in hot climatic regions at the discretion of the Engineer-in-charge if a good bond between the existing surface and the superimposed layer can be ensured.

A.2.2.2. For premixing

{a) For 13.2 mm size coarse aggre­gates

(b) For 11.2 mm size coarse aggregates

9.5 kg-@ 52 kg per m3

5.1 kg-@ 56 kg per ml

*In ease emulsions are used, the quantily reqai.rcd will be 50 per cent of what is indicated.

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me: 14-1977

A.2.2.3. For seal coat {a) Low rainfall sreas {under 150 em

per year) {b) *High rainfall areas (over 150 em

per year)

A.3. Construct.i011

6.8 kg

9.8 kg

A.3.1. Preparation of base : Before the carpet is applied to the existing base, the road must be free from dust or caked mud. Where the existing base is potholed or rutted, these irregularities must be corrected with premixed chippings or coated, macadam, depending upon the depth of the pothole, laid after applying a tack coat of binder and well rammed. thereafter. Where the existing base is extremely porous and absorptive, a suitable primer (vide I.R .C. Tentative Specification for Priming of Base Course with Bituminous Primers) shaH be applied. The surfac~ should be cleaned by:

(a) removing caked earth and other foreign matter with wire brushes,

(b) sweeping with brooms, and

(c) finally dusting with sacks.

A.3.2. Tack coat : The binder should be heated, wherever required, to the appropriate temperature as indicated by the manu· facturers and applied to the base at the rate specified in para A.2.2. It is best to use a sprayer. The binder should be evenly brushed, if need be.

The tack coat should be applied just ahead of the spreading of the premix.

A.3.3. Preparation of premix : Mechanical mixer should be preferred. When only improvised hand mixing drums are available for premixing, place 0.028 m3 of 13.2 mm chippings and 0.014m'l of 11.2 mm cbippings in the mixing drum and mix dry thoroughly. Where straight-run bitumen is used, the aggregates should be suit· ably heated prior to the adding of bitumen.

Add 2.24 kg of the binder, as per quantities given in para A.2 2.2, heated where required. to a temperature suitable to the

* In case emulsions are used , quantity required wlU be 50 per cent of what is indicated.

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IRC: 14-1971

grade of bitumen used, and mix until the chippings are thoroughly coated with the binder.

Empty the premix on to stretchers or wheel barrows and carry to site.

The quantities _of cbippings and binder per batch as given may be proportionately increased if proper coating is possible in one operation.

A.3.4. Spreading of premix : Immediately after applying tbe tack coat, spread the premix with rakes to the desired thickness and camber, or distribute evenly by means of a drag spreader. Cbeck camber by means of a camber board and ev.en out inequalities.

A.3.5. Rolling : As soon as sufficient length, say 15 metres, of the_ premix has been laid, rolling should commence with smooth wheeled rollers (6 to 9 tonnes) or pneumatic tyred rollers. Rolling should commence at the edges and progress towards the centre longitudinally except in the case of superelevated sections where this should commence at the inner edge and proceed towards the outer edge of the curve.

Wben the roller has passed once over the whole area, any high spots or depressions which become apparent should be corrected by removing or adding premixed cbippings. When this. has been done, roll to comapaction. Avoid excessive rolling as this serves no useful purpose and may spoil the carpet.

Moisten the roller wheels to prevent the premix from adhering to the wheels and being picked up.

A.3.6. Application of seal coat : Jn low rainfall areas, i.e. those having rainfall under 150 em per year, a premixed sand­seal coat mixed preferably in a mechanical mixer after heating the sand, should be applied immediately after laying the carpet and rolled. Materials required for this seal coat are· given in paras A.2.1.2. and A.2.2.3.

Jn high rainfall areas, i.e., those having rainfall over ISO. em per year, a liquid seal coat preferably with cbippin~ (though coarse sand can be used), should be applied after laying the carpet. The binder, heated wherever required to the permitted temperature, should oo applied to the cleaned. sorface, blinded with chippings and rolled.

Materials required are given in paras A.2. 1 .2. and A.2.2.3.

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lRC: 14-1971

A .. 3. 7. Surface finish : The finished surface shall be uniform and conform to the lines, grades and typical cross-sections specified. When tested with a 3 metre straight edge, the longitudinal profile of the finished surface shall have no undulation greater than 10 mm, and in any 300 metre length the number of undulations of 6 mm size shall not exceed 30. The cross profile, when checked with a camber template, shall not show a variation of more than 6 mm from the specified profile-

The checking of longitudinal and transverse profile shall be canjed out in accordance with the methods and procedures descri­bed in IRC Special Publication 11 "Handbook of Quality Control for Construction of Roads and Runways".

A.4. Opening to Traffic Traffic may be allowed on tbe road preferably 24 hours after

providing the seal coat. This should be considered the minimum period when the binder 11sed is a cutback or emulsion.

B. 2 CM THICK TAR CARPET

B:t . M.terials

B. I. 1. Binder : The binder sba U be a road tar of grade R .T 3 or R T-4 (No. IS: 21 5- 1961).

B-1-2. Coarse aggregates: The aggregates shall consist of angular fragments and be clean, bard, tough, durable and of uni­form quality throughout. They shall be crushed rock, gravel, .river shingle or slag and should be free of elongated or flaky pieces, soft and disintegrated material. and vegetable or other deleterious matter. The aggregates shall also. sat•sfy the following properties :

Property I Value

----------------------------------~·

j Method of test

1. Abrasion value, using Los Angeles max. 35% IS: 2386 (Part IV) machine

or Aggregate impact value

2. Falkiness index 3. Stripping value 4. Water absorption {except in case of

slags) s. Soundness : Loss with sodium sulphate

-S cycles (in ca$e of slag only) 6. Unit weight or bulk density

(in case of slag only)

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ffi3X. 30% max. 30% max. 25% max. 2%

IS : 2386 (Part IV) JS : 2386 (Part I) IS : 6241 IS : 2386 (Part Ill)

max. J2o/o IS : 2386 (Part V)

min. 1120 kg IS: 2386 [Part III) per m3

m.c: 14-1977

B.J .3. Fine aggregate or sand : As in para A.[ .J. B.2. Quantities of Materials Required

B.2.l. Aggregates B.2.1.1. For carpet

(a) Coarse aggregates 13.2 mm size passing IS 22.4 rom square mesh and retained on JS 11.2 mm square mesh

(b) Coarse aggregates I 1.2 mm size passing IS L.3.2 mm square mesh and retained on lS 5.6 mro square mesh

B.2.1.2. For seal coat

Medium coarse sand or fine grit (passing on lS Sieve No. 1.70 mm and retained on lS Sieve No. 1 80 microns)

8.2.2. Binder

(a) Fot· priming coat (on water~ bound macadam surface}

(b) For tack coat (on an existing black-top surface)

{c) For seal coat

Per 10 m1

of ruau surface o.l8 m3

0.09 m 3

0 .27 m3

Per 10m2 of road surface

0.060 m3

12.2 to 14.7 kg

7.3 to 9.8· kg

9.8 kg

(d) For premixing 19.7 kg @72 kg per m3

B.3. Construction

B.3.1. P reparation of base: As in para A.3.1.

B.3.2. Tack coat : Tbe binder should be heated to 105° to 115o C and should be applied at tbe rates specified in para 8 .2.2.

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IRC: 14-1977

It is best to use a sprayer. The binder should be evenly brushed, if need be.

The tack coat should be applied just ahead of the spreading of the mix.

B.3.3. Preparation of premix : Mechanical mixers should be preferred. When only improvised hand rruxmg d rums are available for premixing, place 0 .028 m 3 of 13.2 mm chippings and 0.014 m3 of 11.2 mm chippings in the mixing drum and mix thorou­ghly dry.

Add 3 kg of road lar heated to l05° to 11 5o C and mix until chippings, preheated if necessary, are thoroughly coated with the binder.

Empty tbe premix on to st retchers or wheel barrows and carry to site.

The quanti t ies of chippings and hinder per batch may be pro-portionately increa~cd if prorer coating is possible in one operation.

B.3.4. Sprcadjog premix : As 10 para A.3.4.

B.3.5. Rolling : As in para A.J.s: B.3.6. Application of seal coat : Immediately after laying

the carpet, the seal coat should be applied in the manner detailed below:

Road ta r IS grade R .T .3, heated to 105° C should be sprayed evenly at 9.8 kg per 10 sq. m. and then it sbould be blinded evenly with med ium coarse dry sand as fine grit at the rate of 0.06 m3

per 10 m1 .

B.3.7. Surface finish: As in para A.3.7.

B.4. Opening to Traffic

Traffic may be allowed on the road 24 bows after providing the seal coat.

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