Digitized by the Internet Archive in 2014 https://archive.org/details/govlawircy2014sp49 New Delhi-11 0 022 August. Sector-6. 2014 Price (Plus Packing : ^ 400/- & Postage) . Puram.K.IRC:SP:49-2014 GUIDELINES FOR THE USE OF DRY LEAN CONCRETE AS SUB-BASE FOR RIGID PAVEMENT (First Revision) Published by: INDIAN ROADS CONGRESS Kama Koti Marg. R. 2009 First Revision August. Delhi-1 1000 Copies 10064 . 1998 Reprinted January. any form or by any means without the permission of the Indian Roads Congress) Printed by India Offset Press. No part of this publication translated or transmitted in shall be reproduced.IRC:SP:49-2014 First Published October. 2014 Rights Reserved. 2006 Reprinted June. 2 General 5 7.4 Transporting 5 7.9 Trial 7.1 Concrete Compressive Strength 4 4.7 Joints 7 7.5 Placing 6 7. i 1 DLC Sub-base 2 2 3.6 Compaction 6 7.3 Water 3 3. Introduction 2.2 Aggregates 2 3.IRC:SP:49-2014 Contents Page No Personnel of the Highways Specifications and Standards Committee 1. Width and Thickness of 3. Drainage Layer 4 6.1 Trial 7.2 Concrete Mix Proportions 4 5. Subgrade 4 7. Materials 4.11 Opening 8 Length Construction to Traffic Annexure -A Test on Curing Annexure -B DLC Compound Test Results from CRRI 7 9 10 .8 Curing 7 7. Construction 5 Mixes 5 7.3 Batching and Mixing 5 7.1 Cement 2 3.4 Mineral Admixtures 3 Concrete Compressive Strength and Concrete Mix Proportioning 4 4.10 Control of Thickness. Density and Strength 8 7. . National Highways. New 4. 16. D. 21. Road Transport & Highways. Ministry of & Highways. Jain.). Ashok 15. S. Haryana 17. Aizwal (Mizoram) (Retd.).K. 14. Haryana 11. C. Pradhan.S. S. Dr. Director (Tech. Dr. Chief Engineer. Chief Engineer. New 13. New MORTH. Marwah.) 5. Professor Dr. N. Ltd. 7. Chaman New Institute. Lai. Consultant. New Delhi Members ' MORTH. Kumar. 2014) & Spl. P. (NH). 7*'^ January. Kurian. L. New Delhi 23. Head. New Delhi. New (Min. Kadiyali Kadiyali. 9. Chief Engineer (Retd. Pateriya. Chief Engineer (Planning). New Delhi Kandasamy. Gupta. R. Chandigarh Delhi Engineer-in-Chief.).L. MORTH.).R. Centre of Transportation Civil Engg. Manchanda. New Chief Executive. Road Research Delhi Delhi PWD. Addl. Bose. Delhi Chief Engineer. Director.K. Bongirwar. Central Dr. Chief Engineer (Retd. Director General (RD) (Convenor) Ministry of Patankar. 12. Prasad.R. Director General. Director General. / Faridabad (Highways). 2. Sunil & FPC T.). New Delhi Delhi Delhi PWD. IITRoorkee. Addl. National Rural MORTH.. LK. (Retd. 20. Bhubaneshwar 24. Panchkula (Haryana) 19.). R. S.. Dr. MORTH. Chief Engineer. S. Mumbai Divn. L 6. of . Kumar. MORTH. B. New DTTDC CRRI. Duhsaka. (Retd). Deptt.S. Kumar.K. Gangopadhyay.K. New Ltd. D. Manoj The Chief Engineer (Member-Secretary) Transport New Road Transport & Delhi Road (R) S.. Advisor. Delhi Delhi Road Development Agency.P DG(RD) & AS 10. i RCD. 18.N. Chief Engineer (Retd.L. Pandey. Jain. of Rural Development). R.C. L. Patna .IRC:SP:49-2014 PERSONNEL OF THE HIGHWAYS SPECIFICATIONS AND STANDARDS COMMITTEE (As on 1. & CRRI PWD (Retd. 3.R&T. Intercontinental Consultants and Technocrats Pvt. to Govt. Satander Ex-Scientist. Haryana State Agricultural Marketing Board. V. Basu. Kumar. Roorkee & Associates. Mahesh Engineer-in-Chief. New Sonipat Delhi Coordinator. of India. 22. Engg. Vanlal 8.. Ministry of (Co-Convenor) Highways. Secy.B. Jain. Jose Chief Engineer. Justo. 2. Kharagpur Members (Kandasamy.K. S. Dr. New Delhi Associate Professor. Indian New ii Delhi Roads Congress. 3. Singh. BRO ADGBR. Nirmal 35. Singh. 399. Delhi Gandhinagar Addl. V. Arun Kumar CEO 30. National New Delhi Limited. Rao. DG(RD) & SS (Retd. 5. Bangalore Highways Authority 31. Delhi Professor. Sharma. M. Raju.V. 334. Vasava. Director General (Retd. New Delhi Corresponding Members 1. 14'^ Main. Director Research and Consultancy. Sharma. S. G.S Engineer-in-Chief (R&B) Rural Road. Advisor. B. DG Jit Yadav. Member New 34.C.R Member (Highways). Deptt. Pandey. Dr. Ministry of Road Transport & Highways.) MORTH.N. (Projects). C. Kanpur Emeritus Fellow. Mumbai NT Kharagpur.B. MORTH. C. New Delhi 32. National Highways Authority (RD) & SS Chief Engineer (Retd. Dr. Delhi Roads & 36.C.. Sinha. H. Sharma. Sarkar. HQ DGBR. India. School of Planning 29. Prof. New & Addl.). & Architecture. C). Vishnu Shankar). Banashankari 2nd Stage. MORTH. MORTH.G. PWD Maharashtra. Hyderabad. S. Representative of 28. New OMR Highways (Technical). .S. Sector-19. of India. Dr. Das. of Transport Planning. 25'" Cross. RK. Momin. New (Shri B. Faridabad 26.V. B. RJ.B. Secretary (Panchayat) Building Dept. New Delhi Secretary Secretary General (Prasad.B. DG(RD) & AS (Retd. Andhra Pradesh 27. Consulting Engineer. Lai). A. Dr. Former Secretary. DG(RD) & AS Animesh (Retd. Bangalore 4.).E. Bhattacharya.).). NT. of Delhi DGBR. Ex-Officio IRC and Director General (Road Development) & Special President. New Delhi 33.IRC:SP:49-2014 25.No. C. Jain. 1 . R.C. Isaac Singia. Prasad.K. TheRigid Pavement (H-3) Committee decided to revise the IRC:SP:49 IRC:SP:49 "Guidelines was published in INTRODUCTION for the with lower 7-day compressive strength as per latest trend other countries. i.!RC:SP:49-2014 GUIDELINES FOR THE USE OF DRY LEAN CONCRETE AS SUB-BASE FOR RIGID PAVEMENT 1 Use of Dry Lean Concrete as Sub-base for Rigid Pavement" 1 998. Ashutosh Sachdeva. Jose Rep.K. Kumar. L. The Highways Specifications and Standards Committee (HSS) approved this document in its meeting held on 7*'' January. Joseph.S. Sitaramanjaneyulu. Dr.N. Kurian. The IRC Council in its meeting held at Guwahati (Assam) on 19*^ January. Venkatesha.R. The composition of the Rigid Pavement Committee (H-3) is given below: Jain. S.C.B. S. PPC and PSC.R. Sengupta as the meeting of H-3 Committee held on 16'*" April.K. P. Col.B. The Executive Committee in its meeting held on 9'^ January.B. Bageshwar Gautam. Shri P. a sub-group under the convenor ship of Dr.K.e. B. flyash & & GBFS. S.L. J.g. for the desired 7-day compressive strength of concrete. Australia also to include mineral admixtures For this task. Dr. V. Ashutosh Gautam & Shri J. Sharma. Krishna. 2014.C. Seehra. A. E-in-C Branch S. LK. of Maiti. Pandey.R. Bongirwar. Shri Members was formed in The draft was prepared based on tests carried out at CRRI on DLC using OPC. K. Kadiyali. Ashok Venkatesh. B. Jain. Col. The Rigid Pavement Committee (H-3) discussed the draft which was prepared by the sub-group in series of meetings. Raman Member-Secretary Members Bongirwar. Convenor Kumar. Dr. The Rigid Pavement Committee (H-3) approved the final draft in its meeting held on 7''' December. Sengupta. Ganju. 2012. Shri M. Maiti including Dr. 2014 approved the draft revision of IRC:SP:49 "Guidelines for the Use of Dry Lean Concrete as Sub-base for Rigid Pavement" for publishing. M. Gupta. The was revised draft in other Countries e. Satander Co-Convenor Kumar. L. Prabhat Tipnis. Manoj CMA Rep.L. K. Dr. V.N. S. 2014 approved this document for placing before the IRC Council for approval. Kadiyali. 2013 for placing before the HSS Committee. Dr. Indian Roads Congress 2 WIDTH AND THICKNESS OF DLC SUB-BASE extend beyond the pavement edges by 500 mm to facilitate further construction operations and provide an adequate support for the concrete slab. B. Vishnu Shankar). Ministry of Road Transport and Highways Secretary General (Prasad.5 percent. Vishal Ex-Officio .E.2 cement soil contains soluble sulphates with slag content upto Aggregates in 50 percent. Nakra. 2 . The DLC Sub=base shall Although the actual thickness will be governed by the design considerations. For further details. The aggregates shall not be alkali-reactive.G. Cement (OPC) i) Ordinary Portland ii) Portland Pozzolana iii) Portland Slag IS:8112. C. hard. When DLC is adopted as sub base in case of roads other than the above roads its thickness of 100 is recommended. strong. Vinod Justo. The off-set will be 200 mm in case of semi mechanized or manual construction. the same may be washed and water drained out at least 72 hours before batching. a thickness of minimum 150 is recommended for all major projects of State Highways and National Highways.IRC:SP:49-2014 Corresponding Members De. the cement used shall be sulphate resisting portland cement conforming to IS: 12330 or Portland If the subgrade slag 3. Coarse aggregate shall consist of clean. Members President. The extra width facilitates the movement of paver tracks on the extended DLC. Brig. Dr.1 Any MATERIALS Cement of the following types of cement may be used with the approval of the Engineer. ' " Aggregates for dry lean concrete shall be natural aggregate complying with IS:383. may be referred.C. where in different combinations sub bases involving cement treated bases have also been provided. In case the aggregates are not free from dirt. Rajesh Thombre. elongated.A. flaky. IRC and Director General (Road Development) & Special Secretary (Kandasamy. S. C). Reddi Madan. crushed stone or gravel and dense and non-porous pieces of shall not consist of disintegrated stone. IRC:62 'Guidelines for Design mm mm and Construction of Low Volume of constructing other type of Roads'. soft. 3 3. IS:12269 Cement ((PPC) IS:1489 (part Cement (PSC) 1) IS:455 a concentration more than 0. The deleterious materials content shall not exceed the limits as per IS:383. . accordance with IS:383. 3 in the . be free from soft particles. cemented particles. Site mixing of flyash or GBFS shall be permitted only equipments at site for uniform blending through a specific with automated process control like batching and mixing plant. and granulated blast Flyash. and in such case. Water used for mixing and curing of concrete shall Mineral Admixtures 3. The mm. Aggregates which have water absorption of more than 3 percent.5 The fine and shall aggregate size of the coarse aggregate shall be absorption of the aggregates shall not exceed 3 percent. The water 26. vegetable matter or other substances harmful to concrete. the Ordinary Portland cement content shall not be less than 1 00 kg/m^ of concrete. Potable water is generally considered satisfactory for mixing and curing. natural sand or crushed stone sand or a combination conform shall to IS:383. sugar. IRC:SP:49-2014 very angular or splintery pieces. alkali.2. loam.75 mm 2. 3.50 300 micron 75-95 50-70 30-55 17-42 8-22 7-17 150 micron 2-12 75 micron 0-10 600 micron Water 3.1 in Grading of aggregates or IV as given The grading of fine aggregate shall conform to grading zones or IS:383. The fine aggregate shall of the two maximum consist of clean.50 mm 4. The pH value of water for mixing and curing upto 9 shall be permitted.36 mm 100 26.3 be clean and free from injurious amounts of oil. The flyash shall conform to IS:381 2 (Part 1 ). mica. Water shall meet the requirements of IS:456.4 Ground Granulated Blast Furnace Slag (GBFS). 15-30 percent or furnace slag shall conform to 18:12089. shall not be used. clay.00 mm 9. salt. Table 1 II. 25-50 percent by weight of cementitious material may be used in concrete as part replacement of Ordinary Portland cement. The grading of combined aggregate shall conform to Table 1 I. after ensuring availability of the mechanized All facility materials shall be stored in proper places so as to prevent their deterioration or contamination by foreign matter to ensure their satisfactory quality and fitness for use work. organic and other foreign matter sea shell. III in IRC:15 Grading of Aggregates Sieve Designation Percentage Passing (by Weight) mm 19. acid. 1 The average compressive not be less than 7 MPa strength of each consecutive group of 5 concrete cubes shall compressive strength of any individual 7 days.5 MPa requirements shall be worked out before at start of work.4.5. Trial mixes of dry lean concrete shall be prepared with water content of 5. that is normally specified.5 and 7. must be properly back-filled and compacted to avoid any weak spot. 5 To DRAINAGE LAYER subgrade. be increased as necessary.0. The flyash or GBFS content shall be 15-30 percent or 25-50 percent by weight of cementltious materials respectively. 6. the subgrade surface shall be given a fine spray of water and rolled with one or two passes of a smooth wheeled roller after a lapse of 2-3 hours in order to stabilise loose surface. the construction traffic shall be avoided on the prepared subgrade. A day before placing of the sub-base.0. The concrete mix proportions are based on Central Road Research Institute (CRRI) test results (Annexure-B). another fine spray of water may be applied just shall not be laid before placing the sub-base. the DLC may have 1 percent higher moisture content. as given in Clause 3. the wheels of the roller. a low in-situ strength and an open textured surface. 4 . 5.2 The concrete mix shall be proportioned with a maximum aggregate cement ratio of 14:1 where ORG is used and 12:1 where PPC or PSC is used. In addition. The design mix complying with these at 7 days. As far as possible. For further details on the drainage layer. if any. If this minimum cementltious materials not sufficient to produce the concrete of the specified strength. surface trenches and soft spots. Special vibratory hammer shall be used for compacting the specimens. Too much water will cause the concrete to be heaving up before the wheels and to be picked up on Too little water will lead to inadequate compaction and segregation. the concrete cube shall not be less than 5. to compensate evaporation loss during transport. Reference may be made to IS:2720 (Part 8) for this. The lean concrete sub-base on a subgrade softened by rain after its final preparation. Concrete Mix Proportions 4.0 percent of the total weight of material. The minimum cementltious materials content shall not be less than 140 kg/cum of concrete. While laying sub-base in main carriageway. IRC:58 may be consulted. facilitate quick disposal of water that 6 is likely to enter the SUBGRADE The subgrade shall conform to the grades and cross-sections on the drawings and shall be uniformly compacted to the modified Proctor density not less than 97 percent. Optimum moisture and density shall be established by preparing cubes with varying moisture contents. If found necessary. and moisture-density curve shall be drawn.IRC:SP:49-2014 4 CONCRETE COMPRESSIVE STRENGTH AND CONCRETE MIX PROPORTIONING Concrete Compressive Strength 4. content is it shall The optimum water content shall be decided so as to ensure full compaction under rolling. 6. a drainage layer (GSB) shall be provided below the sub-base throughout the road width. 6.0 percent using cement content requirement of aggregate-cement ratio specified in para 4.4 Transporting Plant mixed lean concrete shall be discharged immediately from the mixer. After the mix design is approved. transported directly where it is to be during transit. The concrete and protected from the weather by covering with tarpaulin shall be transported by tipping trucks.2 will be adhered to.1 Trial CONSTRUCTION Mixes mixes of dry lean concrete shall be prepared with moisture contents of 5. Before production of the mix. After establishing the optimum moisture. Trial If during the construction of the above is trial length.5. 7. to the point laid 5 . The capacity of batching and mixing plant shall be at least 25 percent higher than the proposed capacity for the laying arrangements.5 and 7.2 The pace and programme of the lean concrete sub-base construction shall be matching The suitably with the programme of construction of the cement concrete pavement over sub-base shall be overlaid with Paving Quality Concrete (PQC) pavement not before 7 days it. Calibration of the batching and mixing every month.2. Compaction of the mix shall be done in three layers with vibratory hammer fitted with a square or rectangular foot.0.3 Batching and Mixing The batching plant shall be capable of separately proportioning each type of material by weight. so that the moisture content could be adjusted. after the sub-base construction. a set of six cubes shall be cast at that moisture for the determination of compressive strength at 3 and 7 days.0. a trial section shall be constructed in accordance with para 7. suitable a satisfactory mix. 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 be carried out and mixing. satisfy the strength requirement. natural moisture content of the aggregate should be determined on a day-to-day basis. Other types of mixers shall be permitted subject to demonstration of their satisfactory performance during the trial plant shall at regular intervals. the optimum moisture content determined as changes may be made in the moisture content to achieve The cube specimens prepared with the changed moisture content should unsatisfactory. 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 in a para 7.6.9. 7. normally length construction. The mix finally designed should neither stick to the rollers nor become too dry resulting in ravelling of surface. 6. 5. Optimum moisture and density shall be established by preparing cubes with varying moisture contents.IRC:SP:49-2014 7 7. Trial mixes shall be repeated if the strength is not satisfactory either by increasing cement content or using higher grade of cement. General 7. compactibility of the mix.6 in the overlaying concrete slabs. and Maintenance of Paver Finishers' may be referred. IRC:SP:86 'Guidelines for Selection. and the same as well as the total requirement of rollers for the job shall be determined during trial run by measuring the in-situ density and the scale of the work to be undertaken. shall finishing of the lean concrete shall be carried out as rapidly as possible and the operation shall be arranged so as to ensure that the time between mixing of the first batch of concrete in any transverse section of the layer and the compaction and final finishing of the same shall not exceed 90 minutes. in no case shall exceed 2 hours. 7. chilled water or addition of ice may be resorted to for bringing down the temperature. 7. The paving machine shall have high amplitude ramping bars to give good initial compaction to the sub-base. If necessary. The equipment shall be capable of laying the material in one layer in an even manner without segregation.5 " - / by a hydrostatic paver. the operation may be carried out by two pavers in echelon separated by appropriate distance (15-20 m). the same will be used after establishing its performance. after compaction the total thickness achieved is as specified. Work shall not proceed when the temperature of the concrete exceeds 30°C. any other roller is proposed. Rolling shall commence on the lower edge of camber/one side slope and proceed towards centre/outer edge. It is desirable to stop concreting when the ambient temperature is above 35°C.) shall not be less than 97 percent of that achieved during the trial length construction. so that.4 In addition to the of 6 shall final be a pass . Transverse and longitudinal construction joints shall be staggered by 500-1000 mm and 200-400 mm respectively from the corresponding joints in laying of the two-lane road the overlaying joints 7. For a pavement more than two-lanes. For more details. compacting and be carried out immediately after the material is laid and levelled.1RC:SP:49-2014 Placing 7. if less than 25°C. In order to ensure thorough compaction. This period may be reviewed in the light of the results of the trial length but. After compaction has been completed.3 number passes required for compaction there preliminary pass without vibration to bed the lean concrete down and again a without vibration to remove roller marks and to smoothen the surface. roller shall not stand on the compacted surface for the duration of the curing period except during commencement of next day's work near the location where work it was terminated the previous day.6.6. when the concrete temperature is between 25 and 30°C and 120 minutes. The number of passes required to obtain maximum compaction depends on the thickness of the lean concrete. Compaction 7. In case.6.1 The compaction 7.9. rolling shall be continued on the full width till there is no further visible movement under the roller and the surface is closed. and the weight and type of the roller etc. Double Drum smooth-wheeled vibratory rollers of minimum 80 to 100 KN static weight are considered to be suitable for rolling dry lean concrete. The densities achieved at the edges i. Lean concrete The shall be laid sub-base shall be done in full width. Operation. The dry density obtained (from the average of density obtained from three density holes of 200 mm dia.2 The spreading.6.5 m from the edge shall not be less than 95 percent of that achieved during the trial construction as per para 7. 0.e. free from cracks. shall be spread and compacted. using fresh lean concrete material laid dumpers shall be controlled by moving the dumper back and forth while discharging the mix into and by other means.5 and manholes. ruts or other immediately on completion and all loose. loose material. when the concrete is still green. The curing compound shall be white pigmented type with water retention index of minimum 90 percent. The deficiency should be made up with concrete with aggregates of size 1 0 mm and below. after roughening the surface. advance construction shall be a at least 14 days proposed date of commencement of work. the surface shall be covered with wet hessian for three days. b) If water-curing is not possible. segregated or defective areas shall be corrected by and compacted.IRC:SP:49-2014 Special care shall be exercised during compaction near joints. the work shall be finished straight by placing a channel at the end and placing concrete in slope beyond the channel. Curing As soon as the lean concrete surface is completed. fresh concrete of the grade of parent concrete. recognized laboratory. the supplier shall be required to provide the test certificate from a curing compound be sprayed immediately after rolling is complete. when tested in accordance with the test method given in Annexure-A. of the compacted material shall be starts next day. the surface regularity also should be checked with 3 m straight edge. As soon as the curing compound has lost its tackiness.8 when work The edge joints.9 Trial 7. 7. For repairing honeycombed surface. 7. side forms and around at these points. On the next day the channel is removed and minor cutting to obtain vertical face as per para 7.6 Segregation of concrete the in it 7. At the end of the day's work/stoppage of work due to breakdown of any machinery.9. curing shall commence.7 Joints Day's work shall be stopped by vertical cut back to a vertical face. kerbs. shall be well closed.7 may be needed. defects. In case adequate compaction use of plate vibrator will be permitted. a) Curing shall be done by covering the surface by hessian cloth in two layers which shall be kept continuously moist for 7 days by sprinkling water. gullies The final is not achieved by the roller lean concrete surface on completion of compaction and immediately movement under roller and free from ridges. in the chain. Curing 7.1 The shall Length Construction trial length shall be constructed (in two days). channels. with aggregates of size 10 mm and below. The length of trial minimum of 60 m length and for full width of the pavement. The trial length of the 7 in shall contain the .6. Even paving operation shall be such that the mix does not segregate. It is necessary to check the level of the rolled surface for compliance.6. 7. Any level deficiency should be corrected after applying concrete with aggregate of size 10 mm and below. To check the efficiency of the curing compound. The final surface shall be inspected before overlaying. the curing shall be done by spraying with liquid compound. Similarly. pot holes. so as to demonstrate the soundness of the procedure..10 Control of Thickness. A few cores may be cut so as to check segregation or any other deficiency and also to ascertain strength. The field density of regular work will be compared with this reference density in accordance with para 7. construction procedures shall not be changed. mix proportions.2 in joint involving In cement content that prepared as per para necessary is to achieve the strength stipulated.9. average of these densities shall be determined. 7. be allowed after shall construction with prior approval of the Engineer. In one day trial length of not more than 30 m shall be laid. 8 .5 trial edges. of material laid each day.6. Three density holes shall be made at locations equally spaced along a diagonal that bisect the trial length. These main density holes shall not be made in the strip 500 mm from the edge. The tolerances 7.1 After the construction of the 7. compaction. the trial materials. Density and Strength be ± 10 mm. After the approval of the length construction has laying. the in-situ density of the freshly laid sand replacement method (as per IS:2720 part-8) with 200 mm dia density hole. after making necessary changes in m The width and reversed to inspect trial length shall be constructed the grading of aggregates and the mix to eliminate any segregation of the mix.9. The cube samples shall be compacted.3 trial trial length.m or part thereof laid each day.11 for thickness shall Opening to No heavy commercial sub-base 7 days of after its its Traffic vehicles like trucks and buses construction. material shall be determined by The hardened concrete 7.4 shall be cut over 3 the bottom surface for any segregation taking place. mixes shall be 7. The average density obtained from the three samples collected shall be the reference density and is considered as 100 percent.9. at the been given. cured and tested in accordance with IS:51 6. construction of at least order to determine and demonstrate the optimum moisture content which results the maximum dry density of the mix compacted by the rolling equipment and the minimum 7. IRC:SP:49-2014 one transverse construction hardened concrete and sub-base to be laid subsequently. Light vehicles if be permitted on the lean concrete unavoidable may. mixing. length shall be outside the main works.1.9. however. moisture content. 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 1000 sq.m or part thereof. plant. The lower surface shall not have honey-combing and the aggregates shall not be held loosely The 7. The dry density of the laid material shall be determined from density holes at locations equally spaced along a diagonal that bisects each 2000 sq. ) shall tamping 50 times with the tamper. to which they reduce the evaporation loss of water from the surface of a standard mortar slab. to produce 10 drops of the flow specimen (3 No. The in two layers and top surface of the test slabs the dry surface of the specimens. on each finished with a float. Test Procedure The metal rectangular mould shall be non-absorbent. and shall be kept in the humidity cabinet (with exposure temperature of 38°C and a relative humidity of 35 percent) for 72 hours. The curing compound shall be of such character that. Ordinary portland cement and graded standard sand in the proportion 1 :3 and a water-cement a flow of 35 ± 5 percent. The specimens along with the moulds shall be weighed accurately to the nearest 1 gm. can be determined by test. compound On table.IRC:SP:49-2014 Annexure-A (Refer Clause 7.40 to 0. The mortar test slab in ratio of 0. and 50 mm deep measured on the inside. be made by placing mortar layer. the curing be sprayed. within 1 will be hour of finishing. 9 . After taking out from the humidity cabinet. The size of the mould is 150 x 300 mm at the top. of moisture from the surface of shrinkage or low abrasion resistance hardened dry lean concrete. watertight and rigidly constructed.8) Test on Curing The Compound efficiency of the curing compounds in terms of the extent. the specimens along with the moulds shall be weighed accurately again to the nearest 1 gm. The test method provides the information on the escape the mortar specimen. The average percentage retention of the mixing water shall be shall calculated.44 (by weight) shall be used. it hardens within 30 minutes after application. which of the may lead to loss of strength. 145 x 295 mm at the bottom. . I \c6 CO . in oo ^— m : • ! rvi ml ml 1 1 J CO 00 Ca5 on on o E o 1_ QQ 0) 3 X i M— CO :3 CD . i T-i • 1 j_ : : o o O I"* p iO . ^ < ^ 0) 3 (A Q> on o -I Q 10 CO I : ^ ! «-( I !^] c^i i : «H| . i : . i IRC:SP:49-2014 m in i ro lTi Ln oi „ <^ I '^tl I od! o6 : r-i j t-'i _ i ko r-~- r-<- i i |oi un i-H i ! I . i CO CO ^ ^ ^r l/^ \ : o6 CO '\ I 1 r-i oi LD m no . . (The Official amendments the IRC document would be published by 'Indian Highways' which shall be to this in its periodical. from the date specified therein) . considered as effective and as part of the code/guidelines/manual. etc.