Sustainable Calcination of Magnesium Hydroxide for Magnesium Oxychloride Cement Production

Effects of varying calcination conditions on the chemical and physical properties of magnesium oxide (MgO), an essential component of magnesium-based cement, were investigated using the more sustainable precursor material of magnesium hydroxide [Mg(OH)2]. Extremely pure and thus more reactive MgO was obtained using a 17.6% less-energy-intensive calcination regime compared with industrial-grade MgO obtained from the calcination of dolomitic lime. As a result, the magnesium oxychloride cement (MOC) that was produced from the sustainably sourced MgO obtained a 50% increase in flexural strength and 22% increase in compressive strength. This was mostly due to its homogenous microstructure, consisting predominantly of the phase-5 hydration product, verified visually using a scanning electron microscope (SEM) and crystallographically using X-ray diffraction (XRD). Based on these findings, it has been revealed that the calcination therapies currently used in industry are impractical for both economic and sustainability purposes; MgO can be manufactured in a more sustainable and thus more competitive means, as discovered in this study.