Aluminum Doping and Carbonation Reactivity of γ‑Dicalcium Silicate: Insights from Density Functional Theory Calculations.

In order to achieve efficient carbon capture and recycle of steel slag, it is crucial to enhance its carbonation efficiency. As a key carbonation-active component in steel slag, the carbon capture capacity of dicalcium silicate (C2S) is significantly influenced by impure metal ions. This study systematically explored the influence of Al doping on the carbonation process of γ-C2S using density functional theory (DFT). The results showed that Al tends to occupy the Si sites, weakening the structural stability of the silicate framework and making it more prone to reaction. Subsequent adsorption simulations verified that Al doping activates the carbonation-related groups and the surface bonding environment, which facilitates the initial stage of carbonation. However, Al doping obstructs the adsorption tendency of key adsorbates and raises the energy barrier for hydration and carbonation reactions. At elevated temperatures, the carbonation reaction of Al-doped γ-C2S can still occur at a significant rate due to thermal activation. This study provides insights for promoting the low-carbon resource utilization of steel slag, thereby contributing to the sustainable development of civil engineering.