EFFECTS OF RAW MATERIAL RATIO, CURING TEMPERATURE AND MAGNESIUM OXIDE ACTIVITY ON THE HYDRATION OF BASIC MAGNESIUM SULFATE CEMENT

The heat of hydration release rate and cumulative heat release of basic magnesium sulfate cement (BMSC) were determined by isothermal calorimetry. SEM and XRD were used to analyze the microstructure and phase composition of the hydration products of BMSC. The effects of raw material ratio, temperature, and MgO activity on the hydration exotherm, microstructure, and phase composition of basic magnesium sulfate cement were studied. The results showed that the ratio of raw materials affected the exothermic rate and phase composition of hydrated BMSC. Low-temperature curing led to the poor crystallinity of the strengthening phase in BMSC. Under high-temperature curing, BMSC hydration was more likely to generate Mg(OH) 2 . The effect of magnesium oxide's activity on BMSC hydration was coupled with temperature, which influenceds the phase composition and the degree of crystallization of the strengthening phase.