Effect of Magnesium to Phosphorus Ratio on Properties of Magnesium Phosphate Cement

The effects of the ratio of magnesium to phosphorus (Mg/P) on the compressive strength, bond strength, drying shrinkage and pH value of magnesium phosphate cement (MPC) were investigated. The results show that the consistent effect of the ratio of Mg/P on compressive strength and bond strength, as the ratio increases, the strengths are both first increased and then decreased, and the best ratio is 3:1. For setting time and drying shrinkage, the effects of the ratio of Mg/P are both obvious. Mainly manifested as the increase of the ratio, all of them show a decreasing trend. And the setting time can be shortened by 78%, furthermore, 28d the maximum drying shrinkage rate can be reduced by 29%. The effect of the ratio of Mg/P on pH value is mainly that when the ratio increases, the time of the inflection point of pH value is obviously advanced, and their final pH value is close.