Investigation on Limestone Calcined Clay Cement System

Abstract

The use of supplementary cementitious materials (SCMs); fly ash and granulated BF slag, by lowering clinker content in cement is a viable strategy to bring down CO₂ emission during cement manufacture. Due to the large availability of clay and limestone all over the world, a new ternary cementitious cement system containing calcined clay and limestone could increase clinker substitution to about 50% without significantly influencing cement performance due to the synergy between aluminates from calcined clay and carbonates from limestone. In the present study, mechanical properties of different limestone calcined clay cement blends, prepared maintaining clinker substitution of 0.40, 0.45, 0.50, 0.55 and 0.60 was measured as per Indian standard IS:4031 and showed compressive strength comparable to the minimum strength requirements for blended cements as specified in Indian standard, in case of cement having clinker substitution rate of 0.50. Comparative evaluation of compressive strength of OPC and limestone calcined clay cement showed substantial increase in strength at later ages in case of limestone calcined clay cement as compared to OPC. The heat evolution of limestone calcined clay cement using isothermal calorimeter showed higher heat evolution with early attainment at all ages as compared to OPC. The limestone calcined clay cement showed its resistivity to different aggressive solutions such as seawater, sulfate and chloride solution salts along with lean water up to the period of 12 months.