Factors Affecting the Workability of Concrete

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The water-cement ratio significantly affects the workability of concrete. A higher amount of water per cubic meter increases the fluidity of concrete, which is an important factor affecting workability.

According to Abran’s law, the strength of concrete is directly related to the water-cement ratio. Specifically, the amount of cement in concrete depends entirely on the water-cement ratio. In fresh concrete, water content increases relative to strength as voids decrease. As a result, lower water-cement ratio results in reduction of void volume and solid volume ratio, thereby yielding stronger hardened concrete.

The water-cement ratio essentially measures voids directly related to the amount of empty pore space in hardened concrete. Similarly, the amount of cement in fresh concrete is directly related to the amount of solid in hardened concrete. In the hardened state, the strength of concrete is inversely proportional to the water-cement ratio, as shown in the figure. In particular, the compressive strength of concrete does not strictly follow a hyperbolic curve at low water-cement ratios because while water is available for cement hydration, some amount of the cement paste remains unhydrated.