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 CO 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 CO 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.