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

Introduction/Objective 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. Methods 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. Results 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. Discussion 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. Conclusion 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.