Effects of curing regimes and binder designs on steel slag-based carbonated aerated concrete (CAC): Reaching a balance between pre-hydration and carbonation

Carbonated aerated concrete (CAC) is recognized as a low-energy alternative to conventional aerated concrete. In this study, the effects of curing methods and binder design on CAC performance, microstructure, and phase evolution are examined. A key contribution is the identification of the balance between pre-hydration and carbonation, a critical yet underexplored factor in strength development. It is demonstrated that insufficient pre-hydration retains excess moisture, hindering C₂S carbonation, while excessive pre-hydration restricts CO₂ diffusion. Two criteria are proposed for optimizing the pre-hydration: the reaction degree of C₂S reaching 40 % and the stabilization of the average pore size of the CAC matrix. Additionally, replacing 60 %–80 % of fly ash with steel slag in the binder mix has been shown to enhance carbonation efficiency and mechanical properties while maintaining a desirable dry density. These findings provide a practical framework for refining CAC mix design and curing strategies, facilitating broader application in sustainable construction.