Influence of curing temperature on water resistance of clay solidified by magnesium oxychloride cement and NaHCO₃

Magnesium oxychloride cement (MOC) is an eco-friendly cementitious material whose strength and water resistance are highly sensitive to curing temperature, limiting its practical use. In this study, unconfined compressive strength (UCS) tests, water resistance tests, scanning electron microscopy (SEM), X-ray diffraction (XRD) and mercury intrusion porosimetry (MIP) were utilized to investigate the effects of curing temperature on the UCS and water resistance of clay solidified by MOC and NaHCO₃ with different MgO/MgCl₂ molar ratios. Results showed that a MgO/MgCl₂ molar ratio of 5:1 produced more hydration products, improving unconfined compressive strength and water resistance. Moreover, the curing temperature significantly influences the hydration reaction of MOC, thereby affecting the mechanical behavior of the solidified clay. The addition of NaHCO₃ contributes to the formation of water-insoluble magnesium carbonate, which significantly enhances the water resistance and reducing temperature sensitivity. This research has expanded the applicable maintenance temperature range of MOC and promoted its widespread application.