Effects of different pH chemical additives on the hydration and hardening rules of basic magnesium sulfate cement

In this paper, based on the basic mechanical properties test and microstructure characterization of basic magnesium sulfate cement (BMSC), the effects of different pH chemical additives on the hydration and hardening rules of BMSC was studied, and its mechanism was analyzed. The results show that the chemical additives with acid pH value can inhibit the hydrolysing-bridging reaction of Mg2+ ions in liquid phase, and delay the hydration reaction of BMSC, which is beneficial to the growth and development of 5·1·7 phase and make it good crystallinity; the chemical additives with neutral and alkaline pH value can accelerate the hydrolysing-bridging reaction of Mg2+ ions in liquid phase, and promote the hydration reaction of BMSC, which is conducive to the crystallization and nucleation of 5·1·7 phase and increase the amount of its formation. Therefore, the performance of BMSC can be controlled to a certain extent through the selection of chemical additives.