Developing Low-Carbon Composite Cement Concretes (LC4) Using Continuous Particle Packing Approach

It is known that optimum packing of coarse and finer fractions in grading of aggregates has proved to improve the mechanical, durability and sustainable properties of concretes. In the present work, composite cement (CC) prepared by interblending of fly ash (FA) and granulated blast furnace slag (GBFS) with ordinary Portland cement (OPC) was used to prepare four grades of CC concretes, viz. M20, M30, M40 and M50, based on guidelines recommended by three international standards, viz. Indian Standard 10262:2019 (IS), American Concrete Institute 211.1-91:2000 (ACI), British Standard 8500-2:2015 (BS) and the reference modified Andreassen model (MAM) through ideal packing curves. The main aim of this study is to establish the influence of ideal gradation of total particulate matrix of concrete constituents on fresh, mechanical and sustainable properties of concretes. In the design of MAM-based concrete mixes, the total particulate matter comprising of coarse aggregates, fine aggregates, cement, FA and GBFS was optimized to match the ideal packing curves of MAM. The particle size distribution curves obtained for total particulate matrix of four grades of concretes designed as per IS, ACI and BS are compared with ideal packing curves of MAM. The concrete mixes designed as per MAM showed better sustainable properties and comparable mechanical properties with respect to concrete mixes designed using other international standards.