Indian Roads CongressSpecial Publication 49

GUIDELINES FOR THEUSE OF DRY LEANCONCRETE AS SUB-BASEFOR RIGID PAVEMENT

Published byTHE INDIAN ROADS CONGRESS

Copies can be hadfromThe Secretary, Indian Roads Congress,Jamnagar House, Shahjahan Road,NewDeihi-ilOOll

NEW DELHI 1998 Price Rs. 60/-(plus packing andpostage)

JRC:SP:49~1998

First published October, 1998

(!?~ghtsof Publication andof Translation are reserved)

Printed at Sagar Printers & Publishers, New Delhi-Il 0(XJ3(10(X) copies)

IRC:SP:49 1998

MEMBERS OF THE HIGHWAYS SPECIFICATIONS ANDSTANI)ARDS COMMITTEE

(As on 4.11.97)

I Sin A.I) Narain *(Ponsenor

2 .Shri Indu PrakashMember-Secretary)

3, Shri i.E. Mathur

4 ShriNirrnal ut Singh

S. Prof. Gopal Ranjan

6 Dr AK. Gupta

.7

5,

Dr. 1... R Kadiyali

Maj.G~n.CT. Chari

0 Shri H.P. Jarndar

0 Shri PD. Wani

1! .Shri S.C. Shanna

2.

13

Shri. MV. Patil

Maj . CR. Rainesh

Director General (Road Dcv.) & AddI. Secy. to the Govt.ofIndia, Ministry of Surface Transport (Roads Wing),Transport Bhavan, NEW DELHI-I 10001

Chief Engineer (R). S&RMinistry of Surface Transport (Roads Wing).Transport Bhavan ,NEW DELHI-I 1(XX)IChiefEngineer (Planning)Ministry of Surface Transport (Roads Wing),Transport Bhavan, NEW DELHI-Il0001

ChiefEngineer (T&T)Ministry of SurfaceTransport, (Roads Wing),Transport Bhavan, NEW DELHI- 110001

Pro Vice Chanceller & Prof. of Civil Engg.,University of Roorkee, RDORKEE-247667

i)irector, Central Road Res.Institote, P.O. CRRI,Delhi-Mathura Road, NEW DELHI-i 0020

Chief Consultant, Dr.L.R. Kadiyali & Associates,S-487, lIndFlooi~Greater Kailash-l, NEW DELHI-45Director General (Works), Engineer-in-ChiefsBranch, Amsy Hqrs., Kashn7ir House, i)HQ P.O.,NEW I)ELH1-l 10011

Secretary to the Govt. of Gu~arat,R&B Department,Sardar Bhavan, Block No. 14, Sachivalaya,GANDHINAGAR-3820 10

Secretary (Works), Public Works Department,Mantra]aya, MUMBAI-400032

Chief Engineer,Ministry ofSurface Transport (Roads Wing),Transport Bhavan NEW DELHI-I 10001

Secretary, P.W.D., Mantralaya, MUMBAI-40(X132Secretary to the Govt. of Kansataka P.W.D.,Room No. 610,6th Floor, Multistoried Building,Dr. Anibcdkar Road, BANGALOR.E-5600)t I

* ADG)R) being not in position. the meeting was presided by Shra AD. Narain,DG(RD), Govt. of india, MOST

IRC:SP:49- 1998

14 Shri iC. Bhandari

15. ShriP,K,Sah

16. Prof. AK. Sharnia

7 Shri OP. Agat~ala

IS. Shri V. Murahari Reddy

19. Stir) K.B.LaI Singhai

20. Shri S.C. Pandey

2!. Shri Pt). Agarwal

22. ,Shri R.K. Sharma

23. Shri E).N. Banerjee

24. Shri R.L. Koul

25. Shri KB. Rajoria

26. Shri Vinod Kumar

27. Prof. G.V. Rao

ChiefEngineer (Mech.)Ministry of Surface Transport (Roads Wing),Transport BhavanNEW DELHI-I 10001

Dy. Director General (Design & Specification Cell)Directorate General Border Roads, Kashmir House,DHQ P.O. NEW DELHI-I 10011Head of Depti. ofTransport Planning,School of Planning & Architecture, 4, Block B,I.P. Estate, NEW DELHI-I 10002

ChiefEngineer (B) S&RMinistry of Surface Transport, (Roads Wing),Transport Bhavan, NEW DELHI-I 10001

Engineer-in-Chief, R&B Department, A&E,Errum Man:zil, HYDERABAD-500082

Engineer.4n.Chief, Haryana Public Works Deptt.,B&R, Sector 19-B, CHANDIGARH-1600l9

Chief Engineer (NH), MP. Public WorksDepartment, ~DWing, 1st Floor, Satpura Bhavan,BHOPAL-462004 (Madhya Pradesh)Chief Engineer (National Highways), U.P. PublicWorks Department. 3, PWD Quarters, Kabir Marg,Clay Square, LUCKNOW-226001

Engineer-in-Chief, Public Works Department,U.S. Club, SHIMLA-17 1001

The Engineer-in-Chief& Ex-Officio Secy.,Public Works Department, G Block (2nd Floor),Writers Buildings, CALCU1TA-700001

Member National Highway Authority of India,1, Eastern Avenue, Ma}iarani Bagh,NEW DELHI-I 10065

Engineer-in-Chief, PW[) Zone I, Govt. of DelhiKG. Marg, NEW DELHI-I 10001

Director & Head, Civil Engg. Department,Bureau of Indian Standards, Manak Bhavan,9, Bahadur Shah Zafar Marg, NEW DELHI- 110002

Deptt. of Civil Engg., LIT., Delhi Hauz Khas,NEW DELHI-I 10016

Dy. Director & Head, Civil Engg. Department,G.S.IT.S., H-55, M.I.G., INDORE-452008

2S. Dr. OP. Bhatia

IRC:SP:49-1998

29 Sod D.P. Gupta

3)) Shri K.K. Sarin

3! Prof. C.G Swaminathan

32. Prof (E.G. insto

33 Prof. N. Ranganathan

34. Shri M.K. Agarwal

35. 1)r. AK. Bhatnagar

36. The ChiefEngineer

37 The Director

:ts. The PresidentIndian Roads Congress

39. The Director General(Road t)evelopment),

40. The SecretaryIndian Roads Congress

I Dr. Yudhhir

2, Dr. V.M. Sharma

3. Dr. S. Raghava Chari

DG(RD), MOST (Retd.) E-44,GreaterKailash (Part I) Enclave, NEW DELHI-I 10(148

DG(RD), MOST (Retd.), S-l08, Panchshila Park,NEW DELHI-I 10017

Badri, 50, Thiruvangadarn Street, R.A. Puram,CHENNAI-600028

Emeritus Fellow 334, 25th Cross, 14th Main,Banashankari 2nd Stage, BANGALORE-560070

Head of Deptt. ofTransportation P1g.,SPA(Retd.)Consultant, 458/C/SFS, Shaikh Sarai I,NEWDELHI-l 10017

Engineer-in-Chief (Retd.), House No.40, Sector 16,PANCHKULA- 134109

Executive Director, Indian Oil Corporation Ltd.,(R&D Centre), Sector- 13, FARIDABAD-121007National Highway, AssamPublic Works Department,Dispur, GUWAHATI-78 1006

Highways Research Station, 76, Sarthat Patel Road,CHENNAI-600025

HP. iamdar, - Ex-OfficioSecretary to the Govt. of Gujarat,R&B Department, Gandhinagar

Ministry ofSurface Transport - Ex-Officio(Roads Wing), New DelhiAD, Narain(,

(S.C. Sharma), - Ex-OfficioChief Engineer, MOST

CORRESPONDING MEMBERS

House No. 642, lIT Campus. P.O. liT, KANPUR-2080 16

Consultant, AIMIL, A-S. Mohan Cooperative IndustrialEstate, Naimex House, MathuraRoad, NEW DELHI.44

Emeritus Professor JNTU, H,No. 16-11-20/5/5,Dilsukhnagar-3, HYDERABAD-500036

Past President, IRC, A-47/1 344, Adarshnagar,Worli, Mumbai-400025

4. Stir) NV. Merani

I1tC:SP:49- 1998

CONTENTS

Page No.

I. Introduction

2. Width and Thickness ofDLC Sub-base 2

3. Materials 24. Pmportioning o(Mataials for the Mix 45. Subgrade 56. Construction 5

IRC:SP:49-1998

GUIDELINES FOR THEUSE OF DRY LEAN CONCRETE ASSUB-BASE FOR RIGID PAVEMENT

L INTRODUCTtON

1. The draft Guidelines for the use of Dry Lean Concrete as~ub~basefor Rigid Pavements prepared by sonic members of the newlyconstituted committee of Rigid Pavement Committee (H-5) was discussedduring the first meeting held on 1.9.97 (personnel given below), The draftwas finalised after incorporating certain changes and modificationssuggested by the members of the Committee.

Dr. L.R. KadiyaliCE(NH) & it. Secretary(SI. Patel)M.C. Veukatesha

Convenor- Co-Convenor

MEMBERS

Member-Secretary

H.S. BhatiaSudesh DhimanR.K. lainDr. C.E.G. JustoI)r. S.C. MaitiS.S. MominB.V.B. PaiYR. Phull

Director, HRS, Chennai

Secretary, IRC(S.C. Sharma)

K.N. RaiDr. S.S. SeehraArun Kumar SharrnaBrajendra SinghV.K. SinhaDr. R.M. VasanCE(R), Municipal Corporation ofGreater Bombay

Kanti Bhushan BhaumikH.K. Kulshrestha

Prof. D.A. ShastryDr. J.N. MandalS.M. Sabnis

President. IRC.(H.P. Jamdar),

EX-OFFICIOMEMBERS

DG(RD), MOST(AD. Narain),

CORRESPONDING MEMBER

IRC:SP:49-1998

[he guidelines were discussed and approved b~HighwaySpecifications & Standards Committee iti its meeting held on 4. 1.97, Thegutdelities were approved by the Executive Committee and the Council intheir meetings held on 29.1 1.97 and on 5.1,98 respectively.

1.2. The provision of a sub-base below the concrete pavements hasmany advantages such as prevention of pumping, availability of a firmslruclural support fot construction equipment and enhancing the pavementperformance under frost conditions. The cement-bound sub-base is one ofthe commonly adopted materials because of a wide variety of accruingbenefits. These include provision of a uniform and strong support; highresistance to deformation and frost action; preventionof pumping; controlof volume changes in expansive soils; and improved load transfer atpavement ~oLnts.Some design practices take advantage of the provision ofcement-treated sub-bases in recommending a higher soil support value.Dry Lean Concrete (DLC) is one of the most popular cement treatedsub- bases,

The guidelines given here cover all aspects ofconstruction ofDLC

sub-base.

2. WIDTH AND THICKNESS OF DLC SUB-BASE

The i)LC sub-base shall extend beyond the pavementedges by Socm to facilitate further construction operations and provide an adequatesupport for the concrete slab. The extra width facilitates the retrieval andreuse of concrete that collects outside the paver.

A thickness of 100mm or 150 mm is commonly followed, thougha thickness of I 5() mm is recommended for all major projects. Actualthickness will be governed by design considerations.

3. MATERIALS

Cement:Any of the following types of cement may be used with

prt or approval of the engineer:1) Ordinary Portland Cement IS: 269.8112 and 12269it) Portland Slag Cement IS: 455iii) Portland Pozzolana Cement IS: 1489

If the suhgrade is found to consist of soluble suiphates in aconcentration more than 0.5 per cent, the cement used shall be sulphatereststant and shall conform to IS:6909.

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IRC:SP:49- 1998

Aggregates:Aggregates for lean concrete shallbe naturalmaterialcomplying with IS:383. The aggregates shall not be alkali reactive, Thelimits of deleterious materials shall not exceed the requirements set out inIS: 383. In case the aggregates are not free from dirt, the same may bewashed and drained for at least 72 hours before batching.

Coarse aggregate shall consist of clean, hard, strong, dense,non-porous and durable pieces of crushed stone or gravel and shall bedevoid of pieces of disintegrated stone, soft, flaky, elongated, very angularor splintery pieces. The maximum size of the coarse aggregate shall he25mm. The water absorption in the aggregates shaH not exceed 2 per cent.

The fine aggregate shall consist of clean, natural sand or crushedstone sand or a combination of the two and shall conform to IS:383. Fineaggregate shall be free from soft particles, clay, shale, loam, cementedparticles, mica, organic and other foreign matter.

The coarse and fine aggregates may be obtained in either of thefollowing manner:

i) In separate nominal sizes ofcoarse and fine aggregates and mixedtogether intimately before use

ii) Separately as 25 mm nominal single size, 12.5 mm nominal sizegraded aggregates and fine aggregate of crushed stone dust orsand or combination of these two

The material after blending shall conform to the grading as

indicated, Table I.

TABLE I: Aggregate Gradation for Dry LeanConcrete

Sive Designation Percentage passisng the sieve byweight

26.50mm 10019.00mm 80-1009.50 mm 55-754.75 mm 35-60600 micron 10-3575 micron 0-8

Water used for mixing and curing of concrete shall be clean andfree from injurious amounts of oil, salt, acid, vegetable matter or othersubstances harmful to the finished concrete. It shall meet the requirements

3

IRC:SP:49- 1998

stipulated in IS:456, except in respect of alkalinity, where a pH value ofupto 9 may be permitted.

All materials shall be stored in proper places so as to prevent theirdeterioration or contamination by foreign matter and to ensure theirsatisfactory quality and fitness for use in the work.

4. PROPORTIONING OF MATERIALS FOR THE MIX

4.1. The Mix shall be proportioned witha maximum aggregatecementratio of 15:1. The water content shall be adjusted to the optimum as perpara 4.2 for facilitating compaction by rolling. The strength and densityrequirements of concrete shall be determined in accordance with para 6.8by making trial mixes.

4.2. Moisture Content

The right amount of water for the lean concrete in the main workshall be decided so as to ensure full compaction under rolling and shall heassessed at the time of rolling the trial length. Too much water will causethe l~anconcrete to be heaving up before the wheels and to be picked upon the wheels of the roller and too little will lead to inadequate compaction,a low in-situ strength and an open-textured surface.

The optimum water content shall be determined and demonstratedby rolling during trial length construction. While laying the main work, thelean concrete shall have a moisture content between the optimum andoptimum + I per cent, keeping in view the effectiveness of compactionachieved and to compensate for evaporation losses.

4.3, Cement Content

The minimum cement in the lean concrete shall not be less thanI 50 kg/cum of concrete. If this minimum cement content is not sufficientto produce concrete of the specified strength, it shall be increased asnecessary.

4.4. Cr~creteStrength

The average compressive strength of each consecutive group of 5cubes shall not be less than 10 Mpa at 7 days. In addition, the minimumcompressive strength of any individual cube shall not be less than 7.5 Mpaat 7 days. The design mix complying with these requirements shall beworked out before start of work.

4

IRC:SP:49-I 9985. SUBGRADE

The subgrade shallconformto the grades and cross sections shownon the drawings and shall be uniformly compacted to the design strengththat is normally specified. The lean concrete sub-base shall not be laid ona subgrade softened by rain after its final preparation, surface trenches andsoft spots, if any, must he properly back-filled and compacted to avoid anyweak or soft spot. As far as possible, the construction traffic shall beavoided on the prepared subgrade. A day before placing of the sub-base,the subgrade surface shall be given a fine spray of water rolled with one ortwo passes of a smooth wheeled roller after a lapse of 2-3 hours in order tostabilise loose surface. If found necessary, another fine spray of water mayhe applied just before placing sub-base.

6. CONSTRUCTION

6.1. General

The pace and programme of the lean concrete sub-baseconstruction shall be matching suitably with the programme constructionof the cement concrete pavement over it. The sub-base shall be overlaidwith cement concrete pavement only after 7 days after sub-baseconstruction.

6.2. Batching and Mixing

The batching plant shall be capable of separately proportioningeach type of material by weight. The capacity of batching and mixing plantshall be at least 25 per cent higher than the proposed capacity for the layingarrangements. The batching and mixing shall be carried out preferably ina forced action central batching and mixing plant having necessaryautomatic controls to ensure accurate proportioning and mixing. Othertypes of mixers shall be permitted subject to demonstration of theirsatisfactory performance during the trial length.

6.3. Transporting

Plant mix lean concrete shall be discharged immediately from themixer, transported directly to the point where it is to be laid and protectedfrom the weather by covering with tarpaulin during transit. The concreteshall be transported by tipping trucks, sufficient in number to ensure acontinuous supply of material to feed the laying equipment to work at auniform speed and in an uninterrupted manner. The lead of the batchingplant to the paving site shall be such that the travel time available frommixing to paving as specified inpara 6.5.2 will be adhered to.

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IRC:SP:49- 1998

6.4. Placing

Lean concrete shall he laid by a paver. The equipment shall becapable of laying the material in one layer in an even manner withoutsegregation, so that after compaction the total thickness is as specified. Thepaving machine shallhave high amplitude ramping bars to give good initialcompaction IC) the sub-base.

The laying of the two-lane road sub-base shall be done in fullwidth. For a pavement more than two-lanes, the operation may be carriedout by two payers separated by appropriate distance. Transverse andlongitudinal construction joints shall be staggered by 500-1000 mm and200-400mm respectively from the corresponding joints in the overlayingconcrete slabs,

6.5. Compaction

6.5.1. The compaction shall be carricdout immediately after the materialis laid and levelled. In order to ensure thorough compaction which isessential, rolling shall be continued on the full width till thereis no furthervisible movement under the roller and the surface is closed. The minimumdry density obtained shall be 97 per cent of that achieved during the triallength construction vide para 6.9 the densities achieved at the edges i.e.0.5 in from the edge shallnot be less than 95 percent of that achieved duringthe trial construction vide para 6.9.

6.5.2. The spreading, compacting and finishing of the lean concrete shallhe carried out as rapidly as possible and the operation shall be arranged soas to ertsure that the time between mixing of the first batch of concrete inany transverse section of the layer and the final finishing of the same shallnot exceed 90 minutes when the concrete temperature is between 25 and30 degree celsius and 120 minutes ifless than 25 degree celsius. Thisperiodmay be reviewed in the light of the results of the trial run but in no caseshall it exceed 2 hours. Work shall not proceed when the temperature ofthe concrete exceeds 35 degree celsius. If necessary, chilled water oraddition of ice may be resorted to for bringing down the temperature. It isdesirable to stop concreting when the ambient temperature is above 40degree celsius. After compaction has been completed, roller shall not standon the compa~tedsurface for the duration of thecuring period except duringcommencement of next dayss work near the location where work wasterminated the previous day.

6.5.3. Double Drum smooth-wheeled vibratory rollers of minimum 80to 100 kN static weight are considered to be suitable for rolling dry lean

6

IRC:SP:49- 1998

concrete. In case any other roller is proposed. the same shall be used afterestablishing its perfonnance. The number of passes required to obtainmaximum compaction depends on the thickness of the lean concrete, thecompatibility of the nix, and the weight and type of the roller etc. and thesame as well as the total requirement of rollers for the job shall hedetermined during trial run by measuring the in-situ density and the scaleof the work to be undertaken.

6,5.4. In addition to the number of passes required for compaction there.shall he a preliminary pass without vibration to bed the lean concrete downand again a final pass without vibration to remove roller marks and tosmoothen the surface.

Special care shall he exercised during compaction near joints,kcrhs. channels, side forms and around gullies and manholes. In caseadequate conipact~on is not achieved by the roller at these points. use ofplate vibrator shall he made.

6.5,5. The final lean concrele surface on completion of compaction andimnicdiately before overlaying, shall be well closed, free from movementunder roller and free from ridges, low spots. cracks, loose material, potholes, ruts or other defects. The final surface shall be inspectedimmediately on completion and all loose, segregated ordefective areas shallbe corrected by using fresh lean concrete material laid and compacted. Forrepairing honeycombed surface, concrete with aggregates of size 10 mmand below shall be spread and compacted. It is necessary to check the levelof the rolled surface for compliance. Any level deficiency should hecorrected altcr applying concrete with aggregatesof size 10mm and belowafter roughening the surface. Similarly the surface regularity also shouldhe checked with 3m straight edge. The deficiency should be made up withconcrete with aggregates of size 10 mm and below.

6.5.6. Segregation of concrete in the dumpers shall he controlled bymoving the dumper backand forth while discharging the mix on it and othermeans. Even paving operation shall be such that the mix does not segregate.

6.6. Joints

Days work shall be stoppe.d by veil ical joints. The edge of thecompacted material shall he cut back to a vertical face.

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IRC:SP:49- 1998

6.7. CuringAs soon as the lean concrete surface is completed. curing shall

coin mence. One of the following two methods shall be adopted:a) The curing shall be done by spraying with liquid curing

compound. The curing compound shall be white pigmented ortransparent type with water retention index of 90 per cent whentested in accordance with BS:7542. Curing compound shall hesprayed immediately after rolling is complete. As soon as thecuring compound has lost its tackiness, the surface shalt hecovered with wet hessian for three days.

h) Curing shalt he done by covering the surface by gunnybags/hessian in minimum three layers which shall he keptcontinuously moist for 7 days by sprinkling water.

6.8. Trial Mixes

Trial mixes of dry lean concrete shall be prepared with moisturecontents like 5.0, 5.5, 6.0. 6.5 and 7.0 per cent using cement contentspecified and the specified aggregate grading keeping in view therequirement of aggregate-cement ratio specified in para 4.1. Optimummoisture and density shall be established by preparing cubes with varyingmoisture contents. Compaction of the mix shall be done in threelayers withvibratory hammer fitted with a square or rectangular foot. Afterestablishing the optimum moisture, a set of six cubes shall be cast at thatmnoisture for the determination of compressive strength on third and theseventh day. Trial mixes shall be repeated if the strength is not satisfactoryeither by increasing cement content or using higher grade ofcement. Afterthe niix design is approved, a trial section shall be in accordance with para6.9.

If during the construction of the trial length, the optimum moisturecontent determined as above is to be unsatisfactory, suitable changes mayhe made in the moisture content to achieve a satisfactory mix. The cubespecimens prepared with the changed moisture content should satisfy thestrength requirement. Before production of the mix, natural moisturecontent of the aggregate should be determined on a day-to-day hasts so thatthe moisture content could he adjusted. The mix finally designed shouldneither stick to the rollers nor become too dry resulting in ravelling ofsurface.

6.9 Trial Length

6.9. I The trial length shallhe constructed at least 14 days in advanceofthe proposed date of commencement of work, The length of trial

8

1RC:SP~49-1998

construction shall he a minimum of 60m length and for full width of thepavement. The trial length shall contain the construction of at least onetransverse construction joint involving hardened concrete and sub-base tohe laid subsequently so as to demonstrate the soundness of the procedure.

6.9.2. In order to determine and demonstrate the optimum moisturecontent which results in the maximum dry density of the mix compacted bythe rolling equipment and the minimumcement that is necessary to achievethe strength stipulated, trial mixes shall be prepared as per para 6.8.

6.9.3. Alter the construction of the trial length. the in-situ density of thefreshly laid material shall be determined by sand replacement method with20cm dia density hole. Three density holes shall be made at locationsequally spaced i~1onga diagonal that bisects the trial length; average of thesedensities shall be determined. These main density holes shall not he madein the strip 50cm from the edge. The average density obtained from thethree samples collected shall be the reference density and is considered aslOt.) per cent. The field density of regular work will be compared with thisreference density in accordance with para 6.5.1. A few cores may be cutas to check segregation or any other deficiency and also to ascertainstrength.

6.9.4. The hardened concrete shall be cut over 3 m width and reversedto inspect the bottom surface ~ir any segregation taking place. The triallength shall be constructed after making necessary changes in the gradationof the mix toeliminate segregation of the mix. The lower surface shall nothave honey-combing and the aggregates shall not be held loosely at theedges.

6.9.5. The trial length shall be outside the main works. After theapproval of the trial has been given, the materials, mix proportions, moisturecontent,mixing, laying, compaction plant construction procedures shall nothe changed.

6. 10. Control of Thickness, Density and Strength

The tolerances for thickness shall be 10 mm. The dry density ofthe taid material shall be determined from density holesat locations equallyspaced along a diagonal that bisects each 2000 sq.m. or part thereof ofmaterial laid each day. The control of strength shall be exercised by takingsamples of dry lean concrete for making cubes at the rate of 3 samples foreach I (X)O sq.m. or part thereof laid each day. The samples shall hecompacted, cured and tested in accordance with IS:5l6.

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I RC: SP:49- 1998

6.11. Traffic

No heavy commercial vehicles like trucks and buses shall hepermitted on the lean concrete sub-base after its construction, Lightvehicles if unavoidable may, however, be allowed after 7 days of itsconstruction with prior approval of the Engineer.

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