Research on Water Resistance of Magnesium Phosphate Cement

Effect of different curing conditions on the mechanical and shrinkage properties of magnesium phosphate cement(MPC),the water resistance of MPC with different ratio of n(MgO) to n(KH_2PO_4),the component and microstructure of the hydrated product were studied in this paper.The findings show that the strength of MPC loses greatly when cured in water for 28 d,which indicates that MPC has poor water resistance.The component of raw materials affects the water resistance greatly,and the amount of phosphate has the prominent influence.The primary reason is that some phosphate which has not reacted is dissolved when cured in water for days,it changes the pH value of the solution,so the main hydration product—MgKPO_4·6H_2O dissolves under acid environment resulting in the increasing of porosity and the decrease of strength.