Is It Possible to Make Magnesia-Based Cement Environmentally Friendly?

Magnesia-based cement is recognized for its outstanding mechanical properties, but its environmental impact has not been thoroughly evaluated. This paper employs a comprehensive life cycle assessment methodology to systematically analyze the environmental effects of four kinds of MgO and 10 kinds of magnesia-based cements based on the data in the literature. The impacts include CO₂ emissions, fossil fuel depletion potential, and overall environmental impact indicators. The results indicate that using Salt Lake magnesium residue to prepare MgO, e.g., LB-MgO and DB-MgO, can reduce over 60% of CO₂ emissions, compared with traditional MgO (e.g., L-MgO and D-MgO) prepared with magnesite. Utilizing supplementary cementitious materials (e.g., fly ash and ground granulated blast-furnace slag) as substitutes for clinker in basic sulfate magnesium cement (BMSC) and magnesium phosphate potassium cement (MKPC) can also reduce approximately 16 and 45% of carbon emissions, respectively. In addition, carbonation-reactive magnesium cement (CRMC), which involves carbonation curing and replacing traditional MgO with Salt Lake magnesium residue, is the most environmentally friendly magnesia-based cement with an overall environmental impact indicator of 0.00078.