Enhancing CO₂-Cured cementitious binder with Mg-doped γ-C₂S from high-Mg limestone

This study explores the use of Mg-doped γ-C₂S, an alternative to conventional Portland cement, to address the environmental impact of the cement industry. γ-C₂S, known for low hydration activity, shows promise as a CO₂-cured binder. The research investigates Mg substitution in γ-C₂S synthesis, utilizing high-Mg limestone resources. Varying Mg/Ca ratios in γ-C₂S synthesis promoted bredigite and merwinite phases during calcination, enhancing specific surface area by over 40%. Optimal Mg doping significantly increased carbonation reactivity, resulting in a 20% strength boost (115 MPa) after 24h of CO₂ curing. This improvement is attributed to enhanced crystallinity in carbonation products, namely hydromagnesite, nesquehonite, aragonite, and magnesite, leading to microstructure densification. The findings highlight Mg-doping as a promising strategy to enhance the carbonation performance of γ-C₂S from high-Mg limestone, offering prospects for sustainable construction materials with reduced CO₂ emissions.