Sustainable Calcination of Magnesium Hydroxide for Magnesium Oxychloride Cement Production

Abstract

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)2Mg(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.