Next-generation cementitious binders for low-carbon concrete: Mechanisms, performance, and challenges

The construction industry works to reduce carbon emissions to achieve global climate-mitigation and net-zero objectives. It is under increasing pressure to develop low-carbon building materials. Cement production alone accounts for approximately 7–8% of all man-made CO2 emissions worldwide; thus, it is crucial to develop new generations of cementitious binders to enable low-carbon concrete construction. This lecture-note review provides a comprehensive overview of next-generation low-carbon binder systems from an engineering perspective. These include supplementary cementitious materials (SCM), limestone-calcined-clay cement (lc3), alkali-activated materials and geopolymers, as well as carbon-based technologies currently being developed. A critical examination of the binding mechanisms by which emissions can be reduced, the performance of fresh and hardened binder systems, the durability characteristics of these binder systems, and the implications of their use in structural designs are presented. The role of life-cycle assessment (LCA) in evaluating the true environmental sustainability of various low-carbon binder systems was also discussed, with a focus on the durability–carbon trade-offs that will influence long-term binder-system performance. The identification of key challenges associated with variability of binder materials, standardization, supply-chain constraints, and obtaining reliable long-term performance data, this review emphasized that achieving effective decarbonization of concrete will require an integrated approach that includes both material design and structural-performance assessment.