Indian Roads Congress Special Publication 49
GUIDELINES FOR THE USE OF DRY LEAN CONCRETE AS SUB-BASE FOR RIGID PAVEMENT
Published by THE INDIAN ROADS CONGRESS Copies can be had from The Secretary, Indian Roads Congress, Jamnagar House, Shahjahan Road,
New Deihi-ilOOll NEW DELHI 1998
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Price Rs. 60/(plus packing and postage)
JRC:SP:49~1998
First published October, 1998
(!?~ghtsof Publication and of Translation are reserved)
Printed at Sagar Printers & Publishers, New Delhi-Il 0(XJ3 (10(X) copies)
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IRC:SP:49— 1998 MEMBERS OF THE HIGHWAYS SPECIFICATIONS AND STANI)ARDS COMMITTEE (As on 4.11.97)
Sin A.I) Narain (Pons’enor
I
*
Director General (Road Dcv.) & AddI. Secy. to the Govt. ofIndia, Ministry of Surface Transport (Roads Wing), Transport Bhavan, NE W DELHI-I 10001
2 .Shri
Indu Prakash Member-Secretary)
Chief Engineer (R). S &R Ministry of Surface Transport (Roads Wing). Transport Bhavan ,NEW DELHI-I 1(XX)I
3,
Shri i.E. Mathur
Chief Engineer (Planning) Ministry of Surface Transport (Roads Wing), Transport Bhavan, NEW DELHI-Il 0001
4
ShriNirrnal
ut Singh
Chief Engineer (T&T) Ministry of SurfaceTransport, (Roads Wing), Transport Bhavan, NEW DELHI- 110001
Prof. Gopal Ranjan
Pro Vice Chanceller & Prof. of Civil Engg., University of Roorkee, RDORKEE-247667
6
Dr AK. Gupta
i)irector, Central Road Res.Institote, P.O. CRRI, Delhi-Mathura Road, NEW DELHI-i 0020
.7
Dr. 1 . . . R Kadiyali
5,
Maj.G~n.CT. Chari
Chief Consultant, Dr.L.R. Kadiyali & Associates, S-487, lIndFlooi~Greater Kailash-l, NEW DELHI-45 Director General (Wo rks), Engineer-in-Chief’s Branch, Amsy Hqrs., Kashn7ir House, i)HQ P.O., NEW I)ELH1-l 10011
S.
0
Shri H.P. Jarndar
Secretary to the Govt. of Gu~arat,R&B Department, Sardar Bhavan, Block No. 14, Sachivalaya, GANDHINAGAR-3820 1 0
0 Shri PD. Wani
Secretary (Works), Public Works Department, Mantra]aya, MUMBAI-400032
1! .Shri S.C. Shanna
Chief Engineer, Ministry of Surface Transport (Roads Wing), Transport Bhavan NEW DELHI-I 10001
2. 13
Shri. MV. Patil
Secretary, P.W.D., M antralaya, MUMBAI-40(X132
Maj CR. Rainesh
Secretary 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
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IRC:SP:49- 1998 14
Shri iC. Bhandari
15 . ShriP,K,Sah
Dy. Director General (Design & Specification Cell) Directorate General Border Roads, Kashmir House, DHQ P.O. NEW DELHI-I 10011
16 . Prof. AK. Sharnia
Head of Depti. of Transport Planning, School of Planning & Architecture, 4 , Block B, I.P. Estate, NEW DELHI-I 10002
7 Shri OP. Agat~’ala
Chief Engineer (B) S&R Ministry of Surface Transport, (Roads Wing), Transport Bhavan, NEW DELHI-I 10001
IS. Shri V. M urahari Reddy
Engineer-in-Chief, R&B Department, A&E, Errum Man:zil, HYDERABAD-500082
19 . Stir) K.B.LaI Singhai
Engineer.4n.Chief, Haryana Public Works Deptt., B&R, Sector 19-B, CHANDIGARH-1600l9
20.
Shri S.C. Pandey
2!. Shri Pt). Agarwal
22.
,Shri R.K. Sharma
23. Shri E).N. Banerjee
24.
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Chief Engineer (Mech.) Ministry of Surface Transport (Roads Wing), Transport Bhavan NEW DELHI-I 10001
Shri R.L. Koul
Chief Engineer (NH), MP. Public Works Department, ~D’Wing, 1 st Floor, Satpura Bhavan, BHOPAL-462004 (Madhya Pradesh) Chief Engineer (National Highways), U. P. Public Works 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, CALCU1’TA-700001 Member National Highway Authority of India, 1 , Eastern Avenue, Ma}iarani Bagh, NEW DELHI-I 10065
25. Shri KB. Rajoria
Engineer-in-Chief, PW[) Zone I, Govt. of Delhi KG. Marg, NEW DELHI-I 10001
26. Shri Vinod Kumar
Director & Head, Civil Engg. Department, Bureau of Indian Standards, Manak Bhavan, 9, Bahadur Shah Zafar Marg, NEW DELHI- 110002
27.
Prof. G.V. Rao
Deptt. of Civil Engg., LIT., Delhi Hauz Khas, NEW DELHI-I 10016
2S.
Dr. OP. Bhatia
Dy. Director & Head, Civil Engg. Department, G.S.IT.S., H-55, M.I.G., INDORE-452008
IRC:SP:49-1998 29
Sod D.P. Gupta
DG(RD), MOST (Retd.) E-44, GreaterKailash (Part I) Enclave, NEW DELHI-I 10(148
3 )) Shri K.K. Sarin
DG(RD), MOST (Retd.), S-l08, Panchshila Park, NEW DELHI-I 10017
3! Prof. C.G Swaminathan
‘Badri’, 50, Thiruvangadarn Street, R.A. Puram, CHENNAI-600028
32. Prof (‘E.G. insto
Emeritus Fellow 334, 25th Cross, 14th Main, Banashankari 2nd Stage, BANGALORE-560070
33 Prof. N. Ranganathan
Head of Deptt. of T ransportation P1g.,SPA(Retd.) Consultant, 458/C/SFS, Shaikh Sarai I, NEWDELHI-l 10017
34. Shri M.K. Agarwal
Engineer-in-Chief (Retd.), House No.40, Sector 16 , PANCHKULA- 134109
35. 1)r. AK. Bhatnagar
Executive Director, Indian Oil Corporation Ltd., (R&D Centre), Sector- 13, FARIDABAD-1 21007
36.
The Chief Engineer
National Highway, AssamPublic Works Department, Dispur, GUWAHATI-78 1006
37
The Director
Highways Research Station, 76, Sarthat Patel Road, CHENNAI-600025
:ts.
The President Indian Roads Congress
HP. iamdar, Secretary to the Govt. of Gujarat, R&B Department, Gandhinagar
39.
The Director General (Road t)evelopment),
Ministry of Surface Transport (Roads Wing), New Delhi AD, Narain’(,
40.
The Secretary Indian Roads Congress
(S.C. Sharma), Chief Engineer, MOST
-
Ex-Officio
-
Ex-Officio
-
Ex-Officio
CORRESPONDING MEMBERS I
Dr. Yudhhir
House No. 642, lIT Campus. P.O. liT, KANPUR-2080 16
2,
Dr. V.M. Sharma
Consultant, AIMIL, A-S. Mohan Cooperative Industrial Estate, Naimex House, MathuraRoad, NEW DELHI.44
3.
Dr. S. RaghavaChari
Emeritus Professor JNTU, H,No. 16-11-20/5/5, Dilsukhnagar-3, HYDERABAD-500036
Stir) NV. Merani
Past President, IRC, A-47/1 344, Adarshnagar, Worli, Mumbai-400025
4.
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I1tC:SP:49- 1 9 9 8
CONTENTS P a g e N o . I.
Introduction
2.
W id th a n d Thickness of DLC Sub-base
2
3.
M aterials
2
4.
Pmportioning o(Mataials fo r th e M ix
4
5.
Subgrade
5
C o n stru ctio n
5
6.
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IRC:SP:49-1998
GUIDELINES FOR THE USE OF DRY LEAN CONCRETE AS SUB-BASE FOR RIGID PAVEMENT
L INTRODUCTtON
The draft Guidelines for the use of Dry Lean Concrete as ~ub~basefor Rigid Pavements prepared by sonic members of the newly constituted committee of Rigid Pavement Committee (H-5) was discussed during the first meeting held on 1.9.97 (personnel given below), The draft was finalised after incorporating certain changes and modifications suggested by the members of the Committee. 1.
Dr. L.R. Kadiyali CE(NH) & it. Secretary (SI. Patel) M.C. Veukatesha
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Convenor Co-Convenor Member-Secretary
MEMBERS
H.S. Bhatia Sudesh Dhiman R.K. lain Dr. C.E.G. Justo I)r. S.C. Maiti S.S. Momin B.V.B. Pai YR. Phull Director, HRS, Chennai
K.N. Rai Dr. S.S. Seehra Arun Kumar Sharrna Brajendra Singh V.K. Sinha Dr. R.M. Vasan CE(R), Municipal Corporation of Greater Bombay
EX-OFFICIOMEMBERS
D G ( R D ) , M O ST (AD. Narain),
President. IRC. (H.P. Jamdar),
Secretary, IRC (S.C. Sharma)
CORRESPONDING MEMBER Kanti Bhushan Bhaumik H.K. Kulshrestha Prof. D.A. Shastry
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Dr. J.N. Mandal S.M. Sabnis
IRC:SP:49-1998 ‘[‘ h e guidelines were discussed and approved b~Highway Specifications & Standards Committee iti its meeting held on 4. 1.97, The gutdelities were approved by the Executive Committee and the Council in their meetings held on 29.1 1.97 and on 5.1,98 respectively.
The provision of a sub-base below the concrete pavements has 1.2. many advantages such as prevention of pumping, availability of a firm slruclural su pport fot construction equipment and enhancing the pavement performance under frost conditions. The cement-bound sub-base is one of the commonly adopted materials because of a wide variety of accruing benefits. ‘These include provision of a uniform and strong support; high resistance to deformation and frost action; preventionof pumping; control of volume changes in expansive soils; and improved load transfer at pavement ~oLnts.Some design practices take advantage of the provision of cement-treated sub-bases in recommending a higher soil support value. Dry Lean Concrete (DLC) is one of the most popular cement treated sub- bases, The guidelines given here cover all aspects ofconstruction ofDLC sub-base. 2 . W I D T H AND T H IC KN ESS O F DLC SUB-BASE
The i)LC sub-base shall extend beyond the pavement edges by S o cm to facilitate further construction operations and provide an adequate support for the concrete slab. The extra width facilitates the retrieval and reuse of concrete that collects outside the paver.
A thickness of 100mm or 1 5 0 mm is commonly followed, though a thickness of I 5 () mm is recommended for all major projects. Actual thickness 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 it) Portland Slag Cement iii) Portland Pozzolana Cement
IS: 269.8112 a nd 12269 IS : 455
IS : 1489
If the suhgrade is found to consist of soluble suiphates in a concentration more than 0.5 per cent, the cement used shall be sulphate reststant and shall conform to IS:6909. 2 <<
IRC:SP:49- 1998
Aggregates:Aggregates for lean concrete shall be natural material complying with IS:383. The aggregates shall not be alkali reactive, The limits of deleterious materials shall notexceed the requirements set out in IS: 383. In case the aggregates are not free from dirt, the same may be washed 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 be devoid of pieces of disintegrated stone, soft, flaky, elongated, very angular or splintery pieces. The maximum size of the coarse aggregate shall he 25mm. The water absorption in the aggregates shaH not exceed 2 per cent. The fine aggregate shall consist of clean, natural sand or crushed stone sand or a combination of the two and shall conform to IS:383. Fine aggregate shall be free from soft particles, clay, shale, loam, cemented particles, mica, organic and other foreign matter. The coarse and fine aggregates may be obtained in either of the following manner: i)
In separatenominal sizes of coarse and fine aggregates and mixed together intimately before use
ii)
Separately as 25 mm nominal single size, 12.5 m m nominal size graded aggregates and fine aggregate of crushed stone dust or sand o r com bination of these two The material after blending shall conform to the grading as
indicated, Table I. T AB LE
I: Aggregate Gradation for Dry Lean Concrete
Sive Designation 26.50mm 19.00mm
9.50 mm 4.75 mm
6 00 micron 75 micron
Percentage passisng the sieve by weight
100
80-100
55-75 35-60
10-35
0-8
Water used for mixing and curing of concrete shall be clean and free from injurious amounts of oil, salt, acid, vegetable matter or other substances harmful to the finished concrete. It shall meet the requirements <<
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IRC:SP:49- 1998 stipulated in IS:456, except in respect of alkalinity, where a pH value of upto 9 may be permitted. All materials shall be stored in proper places so as to prevent their deterioration or contamination by foreign matter and to ensure their satisfactory quality and fitness for use in the work. 4. PROPORTIONING O F MATERIALS FORTHE MIX
The Mix shall be proportioned with a maximum aggregate cement 4.1. ratio of 15:1. The water content shall be adjusted to the optimum as per para 4.2 for facilitating compaction by rolling. The strength and density requirements of concrete shall be determined in accordance with para 6.8 by making trial mixes.
4.2.
Moisture Content
The right amount of water for the lean concrete in the main work shall be decided so as to ensure full compaction under rolling and shall he assessed at the time of rolling the trial length. Too much water will cause the l~anconcrete to be heaving up before the wheels and to be picked up on 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 demonstrated by rolling during trial length construction. While laying the main work, the lean concrete shall have a moisture content between the optimum and optimum + I per cent, keeping in view the effectiveness of compaction achieved and to compensate for evaporation losses. 4.3,
Cement Content
The minimum cement in the lean concrete shall not be less than I 50 kg/cum of concrete. If this minimum cement content is not sufficient to produce concrete of the specified strength, it shall be increased as necessary. 4.4.
Cr~creteStrength
The average compressive strength of each consecutive group of 5 cubes shall not be less than 10 Mpa at 7 days. In addition, the minimum compressive strength of any individual cube shall not be less than 7.5 Mpa at 7 days. The design mix complying with these requirements shall be worked out before start of work. <<
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IRC:SP:49-I 998 5. S U B G R A D E
The subgrade shallconformto the grades and cross sections shown on the drawings and shall be uniformly compacted to the design strength that is normally specified. The lean concrete sub-base shall not be laid on a subgrade softened by rain after its final preparation, surface trenches and soft spots, if any, must he properly b ack-filled and compacted to avoid any weak or soft spot. As far as possible, the construction traffic shall be avoided 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 o r two passes of a smooth wheeled roller after a lapse of 2-3 hours in order to stabilise loose surface. If f ound necessary, another fine spray of water may he applied just before placing sub-base. 6. CONSTRUCTION
6.1.
General
The pace and programme of the lean concrete sub-base construction shall be matching suitably with the programme construction of the cement concrete pavement over it. The sub-base shall be overlaid with cement concrete pavement only after 7 days after sub-base construction.
Batching and Mixing
6.2.
The batching plant shall be capable of separately proportioning each type of material by weight. The capacity of batching and mixing plant shall be at least 25 per cent higher than the proposed capacity for the laying arrangements. The batching and mixing shall be carried out preferably in a forced action central batching and mixing plant having necessary automatic controls to ensure accurate proportioning and mixing. Other types of mixers shall be permitted subject to demonstration of their satisfactory performance during the trial length.
6.3.
Transporting
Plant mix lean concrete shall be discharged immediately from the mixer, transported directly to the point where it is to be laid and protected from the weather by covering with tarpaulin during transit. The concrete shall be transported by tipping trucks, sufficient in number to ensure a continuous supply of material to feed the laying equipment to work at a uniform speed and in an uninterrupted manner. The lead of the batching plant to the paving site shall be such that the travel time available from mixing 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 be capable of laying the material in one layer in an even manner without segregation, so that after compaction the total thickness is as specified. The paving machine shall have high am plitude ramping barsto give good initial compaction IC ) the sub-base. The laying of the two-lane road sub-base shall be done in full width. For a pavement more than two-lanes, the operation may be carried out by two payers separated by appropriate distance. Transverse and longitudinal construction joints shall be staggered by 500-1000 mm and 200-400mm respectively from the corresponding joints in the overlaying concrete slabs,
6.5.
Compaction
6.5.1. The compaction shall be carricd out immediately after the material is laid and levelled. In order to ensure thorough compaction which is essential, rolling shall be continued o n the full width till there is no further visible movement under the roller and the surface is closed. The minimum dry density obtained shall be 97 per cent of that achieved during the trial length 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 during the trial construction vide para 6.9. 6.5.2. The spreading, compacting and finishing of the lean concrete shall he carried out as rapidly as possible and the operation shall be arranged so as to ertsure that the time between mixing of the first batch of concrete in any transverse section of the layer and the final finishing of the same shall not exceed 90 minutes when the concrete temperature is between 25 and 30 degree celsius and 120 minutes if less than 25 degree celsius. Thisperiod may be reviewed in the light of the results of the trial run but in no case shall it exceed 2 hours. Work shall not proceed when the temperature of the concrete exceeds 35 degree celsius. If necessary, chilled water or addition of ice may be resorted to for bringing down the temperature. It is desirable to stop concreting when the ambient temperature is above 40 degree celsius. After compaction has been completed, roller shall not stand on the compa~tedsurface for the duration of thecuring period except during commencement of next days’s work near the location where work was terminated the previous day. 6.5.3. Double Drum smooth-wheeled vibratory rollers of minimum 80 to 10 0 kN static weight are considered to be suitable for rolling dry lean <<
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IRC:SP:49- 1998 concrete. In case any other roller is proposed. the same shall be used after establishing its perfonnance. The number of passes required to obtain maximum compaction depends on the thickness of the lean concrete, the compatibility of the ‘nix, and the weight and type of the roller etc. and the same as well as the total requirement of rollers for the job shall he determined during trial run by measuring the in-situ density and the scale of the work to be undertaken. 6,5.4.
In additionto the number of passes required for compaction there.
shall he a preliminary pass without vibration to bed thelean concrete down and again a final pass without vibration to remove roller marks and to smoothen the surface.
Special care shall he exercised during compaction near joints, kcrhs. channels, side forms and around gullies and manholes. In case adequate conipact~on is not achieved by the roller at these points. use of plate vibrator shall he made.
The final lean concrele surface on completion of compaction and imnicdiately before overlaying, shall be well closed, free from movement 6.5,5.
under roller and free from ridges, low spots. cracks, loose material, pot
holes, ruts or other defects. The final surface shall be inspected immediately on com pletion and all loose, segregated ordefective areas shall be corrected by using fresh lean concrete material laid and compacted. For repairing honeycombed surface, concrete with aggregates of size 10 m m and below shall be spread and compacted. It is necessary to check the level of the rolled surface for compliance. Any level deficiency should he corrected al’tcr applying concrete with aggregatesof size 10mm and below after roughening the surface. Similarly the surface regularity also should he checked with 3m straight edge. The deficiency should be made up with concrete with aggregates of size 10 mm and below.
6.5.6. Segregation of concrete in the dumpers shall he controlled by moving the dumper back and forth while discharging the mix on it and other means. Even paving operation shall be such that the mix does not segregate. 6.6.
Joints Day’s work shall be stoppe.d by veil ical joints. The edge of the
compacted material shall he cut back to a vertical face.
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IRC:SP:49- 1998 6.7.
Curing
As soon as the lean concrete surface is completed. curing shall coin mence. One of the following two methods shall be adopted:
The curing shall be done by spraying with liquid curing compound. The curing compo und shall be white pigmented or transparent type with water retention index of 90 per cent when
a)
tested in accordance with BS:7542. Curing compound shall he
sprayed immediately after rolling is complete. As soon as the curing compound has lost its tackiness, the surface shalt he covered with wet hessian for three days.
h)
Curing shalt he done by covering the surface by gunny bags/hessian in minimum three layers which shall he kept continuously moist for 7 days b y sprinkling water.
6.8.
Trial Mixes Trial mixes of dry lean concrete shall be prepared with moisture
contents like 5.0, 5.5, 6.0. 6.5 and 7.0 per cent using cement content specified and the specified aggregate grading keeping in view the requirement of aggregate-cement ratio specified in para 4.1. Optimum moisture and density shall be established by preparing cubes with varying moisture contents. Compaction of the mix shall be done in threelayers with vibratory hammer fitted with a square or rectangular foot. After establishing the optimum moisture, a set of six cubes shall be cast at that mnoisture for the determination of compressive strength on third and the seventh day. Trial mixes shall be repeated if the strength is not satisfactory either by increasing cement content or using higher grade ofcement. After the niix design is approved, a trial section shall be in accordance with para 6.9. If during the construction of the trial length, the optimum moisture content determined as above is to be unsatisfactory, suitable changes may he made in the moisture content to achieve a satisfactory mix. The cube specimens prepared with the changed moisture content should satisfy the strength requirement. Before production of the mix, natural moisture content of the aggregate should be determined on a day-to-day hasts so that the moisture content could he adjusted. The mix finally designed should neither stick to the rollers nor become too dry resulting in ravelling of surface. 6.9
Trial Length
The trial length shall he constructed at least 14 days in advanceof 6.9. I the proposed date of commencement of work, The length of trial 8 <<
1RC:SP~49-1998 he a minimum of 60m length and for full width of the pavement. The trial length shall contain the construction of at least one transverse construction joint involving hardened concrete and sub-base to he laid subsequently so as to demonstrate the soundness of the procedure.
construction shall
6.9.2. In order to determine and demonstrate the optimum moisture content which results in the maximum dry density of the mix compacted by the rolling equipment and the minimumcement that is necessary to achieve the strength stipulated, trial mixes shall be prepared as per para 6.8. 6.9.3. Al’ter the construction of the trial length. the in-situ density of the freshly laid material shall be determined by sand replacement method with 20cm dia density hole. Three density holes shall be made at locations equally spaced i~1onga diagonal that bisects the trial length; average of these densities shall be determined. These main density holes shall not he made in the strip 50cm from the edge. The average density obtained from the three samples collected shall be the reference density and is considered as lO t.) per cent. The field density of regular work will be compared with this reference density in accordance with para 6.5.1. A few cores may be cut as to check segregation or any other deficiency and also to ascertain strength. 6.9.4. ‘T ’h e hardened concrete shall be cut over 3 m width and reversed to inspect the bottom surface ~ir any segregation taking place. The trial length shall be constructed after making necessary changes in the gradation of the mix toeliminate segregation of the mix. The lower surface shall not have honey-combing and the aggregates shall not be held loosely at the edges.
6.9.5. The trial length shall be outside the main works. After the approval of the trial has been given, the materials, mix proportions, moisture content,mixing, laying, compaction plant construction procedures shall not he changed. 6. 10. Controlof Thickness, Density and Strength
The tolerances for thickness shall be 10 mm. The dry density of the taid material shall be determined from density holes at locations equally spaced along a diagonal that bisects each 2000 sq.m. or part thereof of material laid each day. The control of strength shall be exercised by taking samples of dry lean concrete for making cubes at the rate of 3 samples for each I (X )O sq.m. or part thereof laid each day. The samples shall he compacted, cured and tested in accordance with IS:5l6.
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I R C : SP:49- 1998
6.11. Traffic No heavy commercial vehicles like trucks and buses shall he permitted on the lean concrete sub-base after its construction, Light vehicles if unavoidable may, however, be allowed after 7 days of its construction with prior approval of the Engineer.
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