Concrete Workability for Different Conditions

The workability requirements for various concrete placement is explained below:

The prerequisites of concrete workability changes along with the range of assortments of construction. Workability of concrete is determined by highly skilled design engineers depending on the concrete strength necessities, the requirements of durability and the for the easiness of the construction at the site.

For the constructions with the utilization of greater percentage of reinforcement, where the space amongst the reinforcement is minimum and additionally, compaction could not be carried out effectively, highly workable concrete like the self-compacting concrete is suggested.

Because the workability of concrete is attained by the higher proportion of water, it diminishes the power of concrete. That is why it is better recommended to make utilization of workability augmenting blends like the air-entraining agents. But the utilization of admixtures might also have the impact on the strength of concrete. So, for vital materials of the building like the slab, columns, and beams, and for structures where the relative strength of concrete is very critical, the extent of workability suggested is not very high. For mass concrete and lightly reinforced concrete structures, the lower extent of workability can be utilized.

The extent or the degree of the workability is assessed with the process of slump test of the concrete while mixing. The slump value suggested for each degree or extent of workability for various positioning conditions of concrete is shown in the table below:

The degree of workability for various placing conditions

Placing Condition	Degree of concrete workability	Slump (mm)
Binding concrete, Shallow Sections Pavement using pavers	Very low	Use compacting factor test as per IS: 1199
Mass concrete, Lightly reinforced sections in slabs, beams, walls, columns, floors, hand placed pavements, canal linings, strip footings	Low	25-75
Heavily Reinforced sections in slabs, columns, walls, slip formwork, pumped concrete	Medium	50 – 100, 75 – 100
Trench fill, in-situ piling	High	100 – 150
Tensile concrete	Very high	Use determination of flow test as per IS: 9103