Magnesium Oxychloride Cement: A Low-Carbon Binder as an Alternative to Portland Cement

Magnesium oxychloride cement (MOC), produced from reactive MgO and MgCl₂, has re-emerged as a promising low-carbon binder due to its rapid setting and high early-age strength. Yet its limited resistance to moisture and immersion remains the principal barrier to broader construction deployment. This review synthesizes the MOC evidence base using a structured approach that combines PRISMA-informed study identification and screening with bibliometric mapping to contextualize research evolution and thematic development. The review follows a structured data extraction of mix design, curing conditions, characterization methods, and performance outcomes. The synthesis confirms that MOC performance is strongly system-dependent. MgO reactivity, MgCl₂ concentration, mixture ratios, and curing regime govern hydration products, microstructure, and durability, accounting for the apparent variation across studies. Comparative assessment shows that improvements in water resistance are most consistently reported for phosphate-based modification, SCM incorporation, and polymer/hybrid strategies. However, benefits are frequently accompanied by trade-offs in workability, setting, strength development, and cost, and reinforcement compatibility and corrosion risk remain insufficiently resolved for structural applications. The review highlights gaps in reporting and durability testing that currently limit cross-study comparability and translation, and it consolidates priority research directions toward standardized protocols, mechanism-based durability design, scale-up validation, and robust sustainability assessment.