Effect of Sodium Acetate Anhydrous on Hydration and Microstructure of Potassium Magnesium Phosphate Cement

The practical applications of potassium potassium phosphate cement (MKPC) are restricted by its rapid setting and hardening and concentrative hydration heat. It is difficult for the conventional retarders to significantly reduce the hydration rate and balance the effects of retarders on setting time and mechanical properties. Effects of sodium acetate anhydrous (SA) on hydration heat release characteristics, working perfor-mance and compressive strength were investigated. Moreover, effects of SA on solid phase components and morphology of hydration products and its mechanism were analyzed by XRD, TG-DSC and SEM. The results indicated that SA inhibited the dissolution of Mg2+ by adsorbing on the surface of MgO. It delayed the hydration rate of MgO and KH2PO4, and lowered the hydration temperature. Thus, as the content of SA increased, the setting time of MKPC was effectively prolonged, while the strength, especially the early strength, decreased. The main hydration products of MKPC with SA were MgKPO4•6H2O, but the quantity of products was reduced. With the increasing content of SA, prismatic or plate crystals were replaced by spherical crystals, and crystal grain size reduced. © 2020, Materials Review Magazine. All right reserved.