Thermal Stability and Kinetics of Formation of Magnesium Oxychloride Phase 3Mg(OH)2∙MgCl2∙8H2O.

In this paper, magnesium oxychloride cement with stoichiometry 3Mg(OH)2∙MgCl2∙8H2O (MOC 3-1-8) was prepared and characterized. The phase composition and kinetics of formation were studied by X-ray diffraction (XRD) and Rietveld analysis of obtained diffractograms. The chemical composition was analyzed using X-ray fluorescence (XRF) and energy dispersive spectroscopy (EDS). Furthermore, scanning electron microscopy (SEM) was used to study morphology, and Fourier Transform Infrared (FT-IR) spectroscopy was also used for the analysis of the prepared sample. In addition, thermal stability was tested using simultaneous thermal analysis (STA) combined with mass spectroscopy (MS). The obtained data gave evidence of the fast formation of MOC 3-1-8, which started to precipitate rapidly. As the length of the time of ripening increased, the amount of MgO decreased, while the amount of MOC 3-1-8 increased. The fast formation of the MOC 3-1-8 phase at an ambient temperature is important for its application in the production of low-energy construction materials, which corresponds with the challenges of a sustainable building industry.