Strength Behavior of Mortar Using Fly Ash as Partial Replacement of Cement

This paper reports the results of an experimental investigation carried out to study the effects of fly ash on strength development of mortar and the optimum use of fly ash in mortar. Cement was partially replaced with six percentages (10%, 20%, 30%, 40%, 50% and 60%) of class F fly ash by weight. Ordinary Portland cement (OPC) mortar was also prepared as reference mortar. Compressive as well as tensile strengths of the mortar specimens were determined at 3, 7, 14, 28, 60 and 90 days. Test results show that strength increases with the increase of fly ash up to an optimum value, beyond which, strength values start decreasing with further addition of fly ash. Among the six fly ash mortars, the optimum amount of cement replacement in mortar is about 40%, which provides 14% higher compressive strength and 8% higher tensile strength as compared to OPC mortar.