Comparison of magnesium oxysulfate (MOS) cement and reactive magnesia cement (RMC) under different curing conditions: Physical properties, mechanisms, and environmental impacts

The potential of MgO cement as a low-carbon alternative is widely acknowledged. However, there has been no systematic comparison of the physical properties, mechanism and environmental impact between reactive MgO cements (RMC) and MOS Cement. This study investigated the hydration and carbonization processes of RMC and MOS cement within the range of reactive MgO/MgSO4 molar ratio from 7 to 350. Results showed that different curing conditions had different impacts on RMC and MOS. Specifically, the density of both materials exhibited an increase, but the strength of RMC was enhanced while that of MOS decreased. Although the carbonate and 517 phases can coexist in MOS specimens under carbonization curing, their combination resulted in a notable strength decrease. Carbon footprint analysis showed that RMC cement had certain advantages in carbon emissions over the entire life cycle. Overall, these research outcomes provided valuable guidance for the design of RMC and MOS cement.