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

Abstract

In this research, after producing reactive magnesia directly from calcination of magnesite, reactive magnesia specimens with fly ash were prepared and cured in two different environments to investigate their long-term mechanical performance by carbonation. To investigate the effect on their microstructures of carbonation, the XRD profiles of the samples were also obtained and investigated. It is found that the strength of reactive magnesia samples is highly affected by the addition rate of reactive magnesia and the curing regime. In spite of the presence of the nesquehonite (MgCO3.3H2O) in the reactive magnesia cements having no portland cement, any type of magnesium carbonate crystal was not found for the cements with portland cement in carbon dioxide curing. The strength increase in reactive magnesia cements can be due to the incorporation of Mg2+ ions to the calcite crystals.