Effect of Mixing on Properties and Microstructure of Magnesium Oxychloride Cement

This paper investigated the effect of mixing on the properties of magnesium oxychloride cement, such as apparent viscosity, setting time, compressive strength, and specific strength as well. The phase composition and crystallographic structure of the cement were determined by X-ray diffraction and scanning electron microscopy. The results indicate that the increases of stirring rate and mixing time change apparent viscosity distinctly, shorten setting time and enhance mechanical property. Magnesium oxychloride cement after mixing for 20 min exhibits the optimal mechanical performance. The effect of stirring rate on the phase composition of magnesium oxychloride cement dominates over the effect of mixing time. The increases of stirring rate and mixing time can increase the dispersion state and accelerate the neutralization, thus promoting the strength of magnesium oxychloride cement due to the formation of stable 5·1·8 phase, needle-like crystals and continuous crystalline structure in the whole cement matrix. The properties and microstructure of magnesium oxychloride cement at a stirring rate of 280 rpm are better than those at 140 rpm.