An Augmentation of Abrams’ Law: Correlate Compressive Strength with Water-binder Ratio of Concrete Containing Fly Ash

The study presents an augmented form of Abrams’ law that describes the relationship between the strength and water-binder ratio of concrete. This augmentation permits the prediction of the compressive strength of concrete containing fly ash regardless of the mass substitutions of cement by fly ash and the testing age within the ranges of 14-120 days.

In the modified Abrams’ law, the (apparent) water-binder ratio is replaced by the effective one in which the reactivity of fly ash is considered, and the substitution ratio of fly ash is included. The empirical parameters in the augmented formula have been determined with multi-linear regression analysis based on experimental data.

The goodness of the curve fitting to this renewed strength formula is excellent. The compressive strength predicted from the augmentation coincides with its measured counterpart in the literature.

Abrams’ law is augmented by introducing effective water-binder ratio and fly ash replacement rate, and verifies it through regression analysis of experimental and literature data. This topic has practical significance and contributes to the mixture design of sustainable concrete.

The Abrams’ formula is basically simple but has restricted limits of validity. The proposed augmentation improves the accuracy of the strength estimation of sustainable concrete mixtures batched with mineral admixtures such as fly ash.