To Study the Mechanical Properties of Limestone Calcined Clay Cement Concrete (LC3-Concrete) at Elevated Temperatures

Abstract

Carbon dioxide (CO2) is a byproduct of a chemical conversion process limestone (CaCO3) is converted to lime (CaO) to produce clinker, causing global warming. As per a report in the year 2018, 4 billion tons of cement is made for construction purposes annually which results in 8% of the worldwide CO2 emissions. A percentage of cement clinker should be replaced by some other cementitious material to lower CO2 emissions for example Fly ash, Silica Fumes, and Slag. The sources of these SCMs may be compromised in near future, as the world is moving toward renewable energy production, so coal power stations are being replaced by environment-friendly processes. Around 74% of the Earth’s crust is made up of clay having alumina and silicate minerals. There are over thirty types of clay, Major clay minerals include kaolinite and bentonite. The kaolinite can be converted into metakaolin by calcination. Metakaolin has an amorphous structure, smaller particle size, and increased specific surface area. So, it will result in more pozzolanic metakaolin. Clay is used to substitute cement in concrete after calcination in combination with limestone and it acts as pozzolanic material in concrete. At room temperature, concrete samples with low kaolinite clay show less strength as compared to control samples having no cement replacement. The samples with more clay proportion show less compressive and tensile strengths at room temperature. The rate of heat transfer in samples having more clay content is less as compared to samples having greater cement content. LC3-30 fails when the temperature rises above 600°C, and samples with more clay content fail earlier at high temperatures. The strength at a specific temperature decreases with the decrease in cement content in concrete. As we move toward high temperatures, the compressive and tensile strength of all clay samples decreases.