Investigation of curing behavior of γ-C2S and MgO under varying CO2 concentrations

The study investigated the mechanical properties and microstructure evolution of MgO-γ-C₂S solidified under 10 % and 100 % CO₂ concentrations. The results suggest that the carbonate phase exhibits enhanced compressive strength as the CO₂ concentration increases from 10 % to 100 %. The development of compressive strength in MgO-γ-C₂S samples is directly correlated with the carbonate content generated by carbonation. The compressive strength of samples carbonated for 8 h at a 10 % CO₂ concentration is equivalent to that of samples carbonated for 4 h at a 100 % CO₂ concentration, highlighting the potential of using lower concentrations. Additionally, CO₂ preferentially adsorbs on the surfaces of γ-C₂S (101) and MgO (010). A significant amount of charge transfer from surface Ca ions to the anti-bonding orbitals of CO₂ molecules is observed on the γ-C₂S (101) surface, revealing the carbonation behavior at the atomic scale. This study provides theoretical guidance for the application of industrial solid waste containing γ-C₂S and MgO, as well as industrial flue gas, in the building materials industry.