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

This study explores the use of Mg-doped gamma-C2S, an alternative to conventional Portland cement, to address the environmental impact of the cement industry. gamma-C2S, known for low hydration activity, shows promise as a CO2-cured binder. The research investigates Mg substitution in gamma-C2S synthesis, utilizing high-Mg limestone resources. Varying Mg/Ca ratios in gamma-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 gamma-C2S from high-Mg limestone, offering prospects for sustainable construction materials with reduced CO2 emissions.