Magnesium Cements as Sustainable Alternatives to Portland Cement: Carbonation Mechanisms, Mechanical Performance, and Environmental Benefits

The construction industry remains one of the major CO₂ emission sources globally because producing Portland cement contributes to about eight percent of total emissions. Sustainable alternatives need development to address climate change effects because limestone calcination produces substantial CO₂ emissions at high energy usage levels. Four types of magnesium cements which include Reactive Magnesia Cement (RMC) Magnesium Phosphate Cement (MPC) Magnesium Oxychloride Cement (MOC) and Magnesium Oxysulfate Cement (MOS) have proven viable alternatives due to their natural carbonation capacity that allows CO₂ absorption. These concrete substitutes deliver better mechanical performance with increased strength together with enhanced durability and fire safety characteristics and they help reduce carbon emissions. The CO₂ sequestration ability of Magnesium Cement increases tremendously through Accelerated Carbonation Curing (ACC) because the process enables formation of stable carbonates like magnesite and nesquehonite. The capture efficiency for CO₂ embodied in RMC reaches 92% while PC captures only 50% thus resulting in improved emissions reduction outcomes. Rapid-setting MPC finds common use for infrastructure repairs because of its exceptional early strength yet MPC and MOC and MOS show top performance as fire-resistant materials and thermal insulation components. MOC and limited large-scale adoption present challenges to full-scale implementation due to their water susceptibility issues. The paper conducts an extensive examination of MC carbonation processes as well as their mechanical properties and environmental benefits while showcasing their viability as sustainable replacement for PC. Future investigations should work on enhancing carbonation process performance while improving water resistance and developing hybrid cement mixtures to quicken the shift toward environmentally sustainable building materials.