Performance and life cycle of Portland limestone cement mixes admixed with gypsum

Abstract

In this study, the life cycle and performance of normal concrete containing 35% limestone and 2% gypsum made in different ratios of water to binder (w/b) were examined. Its cost and CO2 emissions were found to be 13% and 35% lower compared to the control concrete. However, because of the greater replacement of cement with limestone filler, there is a reduction in its workability, the development of heat and strength, and the penetration resistance of water and chloride ions, especially in the early ages. The addition of gypsum marginally improved these concrete properties, but its quantity should be limited to 2% by weight of the binder. The use of gypsum beyond this limit led to a significant decrease in the properties of concrete. Anorthite, a calcium aluminosilicate mineral, was found in this concrete, and its fractured morphology was found to be more occupied with unreacted angular limestone particles. This low-carbon concrete showed an improvement in compressive strength with decreasing w/b ratios. The limestone reserve in India is abundant and spread evenly across its length and depth, and its use as the main replacement for cement in normal strength mixes would greatly reduce the impact of CO2 on the environment.