Workability of concrete. The concrete mix proportions chosen shall be such that the concrete is of adequate workability for the placing conditions of the concrete and can be properly compacted. Following ranges of workability and slump of concrete, measured in accordance with IS: 1199, shall be broadly adopted: Placing conditions Degree of workability Slump (mm) * Mass concrete * Lightly reinforced section in slabs, beams, walls, and columns. * Floor *Footings Low 25-75 *Heavily reinforced sections in slabs, beams, walls, and columns. Medium 50-100 For canal lining, slumps range 50-65 mm is considered adequate. It can be increased unto 75mm, if considered necessary in particular situations for practical usage.
Workability of concrete. The proportions chosen shall be such that the concrete is of adequate workability for the conditions prevailing on the work in question, and shall be properly compacted. Water shall be added to the mixer to give the required workability. The water content of each batch shall be adjusted as necessary to maintain the required workability with simultaneous adjustment of cement concrete such that the water cement ratio is not changed. The workability tests shall be carried out in accordance with IS: 1199 – Latest, “Methods of sampling and analysis". Workability of concrete shall be controlled by direct measurement of water content, making allowance for any surface water in the fine and coarse aggregates. Allowance shall be made for surface water present in the aggregate when computing the water content. Surface water shall be determined by one of the field methods described in IS: 2386, Part III.
Workability of concrete. The concrete mix proportions chosen should be such that concrete is of adequate workability for the placing conditions of the concrete and can properly be compacted with the means available. The definitions of the ranges of "workability" of concrete as measured by either the slump or V-B tests (IS: 1199) and the range to be adopted for different kinds of work unless specified otherwise is given in Table - 2.9. TABLE - 2.9 WORKABILITY OF CONCRETE Placing conditions Degree of Workability Slump (mm) Values of Workability Vee-Bee Compacting Factor Blinding concrete; Shallow Sections' pavements using pavers Very Low 20-10 Secs. 0.75-0.80 Mass concrete; Lightly reinforced sections in slabs, beams, walls, columns, Floors, Hand placed, pavements, Canal ling, Strip footings Low 25 - 75 10-5 secs. 0.80 - 0.85 Heavily reinforced sections in slabs, beams, walls, columns, Slip form works, Pumped concrete. Medium 50-100 75-100 5-2 secs. 0.85- 0.92* Trench fill, in-situ pilling Termite concrete High Very High 100- 150 Workability to be decided by determination of flow Above 0.92** Above (IS-9103) 0.92** Note: For most of the placing conditions, internal vibrators (needle vibrators) are suitable. The diameter of the needle shall be determined based on the density and spacing of reinforcement bars and thickness of sections. For tremix concrete, vibrators are not required to be used.
