Effect of calcination temperature of magnesium silicate on the properties of magnesium phosphate cement

This study reports the use of magnesium silicate (M-S-H) for magnesium phosphate cement (MPC) formulation and aims to study the effect of calcination temperature of the magnesium silicate on mechanical properties and setting time of the MPC. Synthetic magnesium silicate was obtained by precipitation method using solutions of magnesium sulfate and sodium silicate with a molar ratio of Mg/Si = 1. MPC mortars were prepared with a mass ratio of magnesium silicate to potassium phosphate of M-S-H/KH 2 PO 4 = 1. Results showed that mortars prepared with magnesium silicate calcined at temperatures above 700 °C did not set into hardened cement. However, calcination of magnesium silicate at temperature below 700 °C and particularly at 600 and 650 °C enhances the mechanical performance of the cement due to improving the availability of magnesium from magnesium silicate powder to react with phosphate for cement phase formation (K-struvite). MPCs with an optimal compressive strength up to 39 MPa at 28 days were obtained with magnesium silicate calcined at 600 and 650 °C.