Magnesium cements and their carbonation curing: a state-of-the-art review

The Portland cement (PC) production industry is a key contributor of CO₂ emission. The demand of cement is mounting day by day due to the rapid infrastructure development in the world. Consequently, CO₂ discharge from the construction sector is continuously increasing and accounts for about 8% of the total CO₂ emission, which becomes a global concern nowadays. Wide applications of eco-friendly cements can significantly reduce the CO₂ release. Therefore, use of magnesium cements (MCs) might be a promising solution to ease such concern. As a rapid hardening cement, MCs can be characterized as low-carbon due to their lower embodied energy and carbon storage ability during the service. This review mainly summarizes the findings of previous studies related to the carbonation performances of PC blended with magnesia and MCs products, and particularly, the influence of Accelerated carbonation curing (ACC) process on the properties of MCs and corresponding CO₂ sequestration performance. The effects of ACC on mechanical strength, hydration and mineral carbonation mechanisms, pore structures, pore solution pH and thermal properties are discussed. The limitations of existing research are also discussed, which may provide the directions for future research and development of MC material products.