15314Water Cement Ratio and Abrams

Water/cement ratio is the most important factor influencing various kinds of concrete properties. The basic measure usually taken in making high-strength concrete is to reduce the w/c ratio from the values for normal-strength concrete of about 0.5 or higher to about 0.3 or less. This result can be inferred from Abrams' law:

where f is the compressive strength, A is an empirical constant (usually 14,000 psi), and B is a constant depending mostly on the properties of the cement (usually 4).

One of the major drawbacks of a lower w/c ratio is the loss of workability. However, this disadvantage can be overcome by the addition of admixtures. To recover the necessary workability, superplasticizers are usually added to the mix.

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