Long-term mechanical performance of reactive magnesia cements incorporating fly ash

In this research, after producing reactive magnesia (RM) directly from the calcination of magnesite, reactive magnesia cement (RMC) specimens with fly ash were prepared and cured in two different environments to investigate their long-term mechanical performance after carbonation. To investigate the effect of carbonation on microstructure, X-ray diffraction profiles of the RMC samples were obtained and analysed. It was found that the strength of the RMCs was highly affected by the dosage of RM and the curing regime. In spite of the presence of nesquehonite (MgCO₃.3H₂O) in RMCs having no Portland cement (PC), no type of magnesium carbonate crystal was found for the cements with PC after carbon dioxide curing. The strength increase in the RMCs could be due to the incorporation of Mg²⁺ ions in calcite crystals.