Optimization of Cement Replacement by Fly Ash in Compressive Strength of Portland Cement Concrete

Abstract

The production of cement has been known for its additive role in environmental pollution. As a measure of abatement of pollution effort, scientist have evoked the concept of diluting cement with various pozzolanic additive like fly ash, blast furnace slag etc. Many of these additives were found to be acceptable for cement replacement, but their exact role and efficacy remains elusive. In the present study, fly ash was added as a partial replacement of cement, followed by the measurement of compressive strength after curing for periods of 7, 14, 21, 28 and 56 days. The above experiment was conducted after determining the compressive strength of concrete (without fly ash) for periods of 7, 14, 21, 28 and 56 days for comparison purpose. The main findings of the work are: the 28 day compressive strength of concrete up to 30% replacement level (with fly ash) is higher than OPC concrete. However, the compressive strength of concrete above 30% replacement level is lower than OPC concrete. The seven-day compressive strength of concrete at all replacement levels has been found to be lower as compared to concrete without any replacement.