Optimisation of mix proportions of LC3 binders with African clays, based on compressive strength of mortars, and associated hydration aspects

Abstract

A fundamental challenge in the cement industry is related to mitigating its impact on climate change. Emissions of CO2 are becoming more tightly regulated and taxed. There is also the high cost of cement production due to energy consumption. A viable strategy for lowering costs and environmental impact of cement is the partial substitution of cement clinker by additions of calcined kaolinite clay and limestone. In this study, the performance of LC3 mortars with clays from selected deposits in Africa and with a large range of binder combinations is examined based on the compressive strength of mortars and the characterisation of hydration products. LC3 mixes with clinker contents between 40 % to 70 % were selected using the mixture design 3-factors approach. The findings indicate that for optimum performance, for these specific clays, the optimum clinker content is 55 % at which the calcined clay and limestone contents are 35 % and 10 %, respectively.