Development of an Optimum Limestone Calcined Clay Cement (LC3)

Abstract

This thesis presents innovation to make a combined substitution of cement with calcined clay and limestone powder in order to prepare the Limestone Calcined Clay Cement (LC3). The aim was to overall assess the performance of these new binders having higher levels of clinker substitution. This substitution of cement will not only reduce the carbon footprint of these blends but will also utilize the locally available abundant and cheap supplementary cementitious materials (SCMs). The optimum blended mix was developed by studying the effect of the amount of clinker replacement, the ratio of the calcined clay to limestone powder, and the mineralogical composition of the clay system based on fresh properties, microstructural analysis, physical characteristics, and mechanical properties of these blends was evaluated. Scanning electron microscopy (SEM) with Energy-dispersive X-ray (EDX) and X-Ray diffraction (XRD) spectroscopies were also employed to see the morphological and mineralogical structure of the material. The replacement of cement ranged from as low as 30% to as high as 80% with variation in calcined clay to limestone powder ratio from 1:1, 2:1, and 3:1. Loss in strength and physical performance is observed when the replacement of clinker is increased beyond 50%. The thesis also studies the variation of carbon footprint and energy consumption of each blend to determine the blend with highest reduction in carbon emissions.