Evaluation of Fly Ash as a Partial Replacement for Cement in Concrete: Effects on Strength and Durability

This article details a study that looked at the effects of 10%, 20%, and 30% fly ash substitution on the mechanical and durability qualities of concrete. Compressive, tensile, flexural, workability, heat of hydration, and water absorption tests were performed on the resulting mixtures after OPC was partially replaced with fly ash. The best compressive, tensile, and flexural strengths along with durability characteristics were found at the 20 % replacement. The workability increases with an increase in fly ash due to its lubricating effect, which decreased the heat of hydration up to 20 % replacement and then started to rise slightly at 30 % replacement. Water absorption is significantly reduced at 20% fly ash whereas increased at 30% as a result of excess porosity and voids. These observations indicate that 20% fly ash represents the optimum level of substitution in order to strike the balance between the performance under mechanical stress as well as durability, thus would be a sustainable replacement for the conventional cement