Carbonation performance and CO₂ sequestration potential of magnesium oxysulfate cement incorporating thermally activated MgO-rich industrial waste

The development of low-carbon cementitious binders using industrial byproducts offers a viable approach to minimising the ecological impact of the building sector. This research introduces an innovative magnesium oxysulfate cement (MOSC) derived from thermally activated, MgO-dominant industrial byproducts and assesses its mechanical properties, carbonation characteristics, microstructural development, and carbon capture capability under accelerated carbonation conditions. MOSC mortar was evaluated against ordinary Portland cement (OPC) mortar after exposure to 3% CO₂, 65% relative humidity, and 24°C for 56, 63, and 70 days. MOSC demonstrated significantly deeper carbonation than OPC, suggesting improved CO₂ reactivity. Carbonation enhanced the compressive strength and diminished the water absorption of both binders, with MOSC frequently surpassing OPC. Thermogravimetric analysis revealed that the mass loss associated with carbonates in MOSC increased from 1.34% to 3.10%, whereas OPC showed a slight increase from 2.01% to 2.39%, thereby confirming the enhanced carbonation capability of the waste-derived MOSC system. These results indicate that thermally treated MgO-dominant industrial byproducts can be efficiently converted into a sustainable MOSC binder, exhibiting superior carbonation performance, enhanced mechanical properties, and considerable promise for low-carbon building practices.