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Mix Design For DLC: IRC SP-49 2014: Nikhil Saboo, IIT (BHU) Varanasi

The document provides guidelines for mix design of dry lean concrete (DLC) to be used as sub-base in concrete pavements. It specifies requirements such as a minimum thickness of 150mm for major projects, use of cement types based on sulphate content in subgrade, maximum aggregate size and water absorption, aggregate grading and proportions, use of mineral admixtures, minimum cementitious content and strength requirements. It also provides instructions for trial mixes, compaction, curing and construction.

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ABHINAV KUMAR
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1K views7 pages

Mix Design For DLC: IRC SP-49 2014: Nikhil Saboo, IIT (BHU) Varanasi

The document provides guidelines for mix design of dry lean concrete (DLC) to be used as sub-base in concrete pavements. It specifies requirements such as a minimum thickness of 150mm for major projects, use of cement types based on sulphate content in subgrade, maximum aggregate size and water absorption, aggregate grading and proportions, use of mineral admixtures, minimum cementitious content and strength requirements. It also provides instructions for trial mixes, compaction, curing and construction.

Uploaded by

ABHINAV KUMAR
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Mix Design for DLC: IRC SP-

49 2014
Nikhil Saboo, IIT (BHU) Varanasi
• DLC to be used as sub-base in concrete pavements.

• Should extend beyond the pavement edge by 500 mm to facilitate


movement of paver trucks. In case of semi-mechanized or manual
construction the offset should be 200 mm.

• A minimum thickness of 150 mm recommended for all major projects of SH


and NH.

• For other roads: 100 mm.

• Types of cement: OPC, PPC, PSC,

• If subgrade contains soluble sulphates > 0.5%, then cement shall be


sulphate resisting Portland cement or PSC with slag > 50%.
• Maximum size of CA : 26.5 mm; maximum water absorption: 3%.

• Combined aggregate grading:


• Mineral admixtures: Flyash, 15-30% or GBFS, 25-50% by weight of
cementitious materials.

• In any case OPC > 100 kg/m3.

• The average compressive strength of each consecutive group of 5 concrete


cubes shall not be less than 7 MPa at 7 days. In addition, the compressive
strength of any individual concrete cube shall not be less than 5.5 MPa at 7
days.

• Maximum aggregate to cement ratio: 14:1 for OPC and 12:1 for PPC/PSC

• Minimum cementitious material content: 140 kg/m3.

• Increase cemetitious material content if desired strength is not met.


• Optimum water content to be determined for achieving full compaction under rollers.

• Make trial mixes with water content 5-7% by weight of total material.

• Compaction should be done in three layers using a vibratory hammer.

• Moisture-density curves to be drawn.

• While laying 1% higher moisture content may be adopted to compensate for loss due to
evaporation.

• To facilitate quick disposal of water that is likely to enter the subgrade, a drainage layer
(GSB) shall be provided below the sub-base throughout the road width.

• Subgrade to be compacted at minimum 97% of modified proctor density.


• Hydrostatic paver to be used for placing.

• Compaction and final finishing should be completed before 2 hours.

• Work shall not proceed if temperature of concrete > 30 0C

• Double Drum smooth-wheeled vibratory rollers of minimum 80 to


100 KN static weight are considered to be suitable for rolling dry lean
concrete.

• 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.
• Solve: Assume the cement to be OPC, find the quantity required for 5
cubes.

Aggregate Set 1 Aggregate Set 2 Aggregate Set 3 Aggregate Set 4

IS Sieve
Retained % Passing Retained % Passing Retained % Passing Retained % Passing
Designation

Sieve size Specified Grade Limit Mid Point


80 mm 0 0 0 0
63 mm 0 0 0 0
80 mm
40 mm 0 0 0 0
63 mm
26.5 62 0 0 0
40 mm
19 1961 0 0 0
26.5 100 100 100
10 mm 7264 24 0 0
19 75 95 85
4.75 mm 34 820 36 5
2.36 mm 156 48 3 10 mm 50 70 60

0.6 mm 0 255 69 4.75 mm 30 55 42.5


0.3 mm 0 129 112 2.36 mm 17 42 29.5
0.15 mm 0 27 85 0.6 mm 8 22 15
0.075 mm 0 4 24 0.3 mm 7 17 12
Pan 0 1 11 0.15 mm 2 12 7
Total 9321 1000 500 309 0.075 mm 0 10 5

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