22. Composite Cement: A Sustainable Binding Material for Real Time Construction Practice in India

The extraction of lime stone for the manufacturing of cement is a highly energy consuming process that demands high embodied energy. Consumption of supplementary cementitious materials (SCMs) like fly ash (FA) and granulated blast furnace slag (GBFS) results in reduction in energy and carbon emission. Ternary blended composite cement (CC), binary blended Portland slag cement (PSC) and Portland pozzolana cement (PPC) and reference Ordinary Portland Cement (OPC) are used in this study to prepare three grades of concrete viz. M20, M30 and M40 designed as per IS 10262:2019. The energy demand, carbon footprint and cost involved in the preparation are estimated and compared with OPC, PPC, PSC and CC concretes. At 28 days, PPC, PSC and CC concretes exhibited 11.48%, 8.43% and 15.6% lower compressive strength respectively compared to OPC concretes. With respect to M20 grade, PPC, PSC and CC concretes respectively consumed 14.64%, 24.11% and 27.52% less energy than OPC concrete for the same grade. The carbon emission intensity is estimated to be 14.63%, 27.93% and 28.9% less for PPC, PSC and CC concretes respectively compared to OPC. The cost of producing M20 grade of PPC, PSC and CC concretes is about 10.2%, 14.64% and 19.8% lower than OPC concrete production. This difference in energy, carbon emission and cost is found to reduce with increase in grade of concrete for all the blended cements. Composite cement concretes have proven to be energy efficient with less carbon emission and cost compared to OPC, PPC and PSC concretes.