Investigation of the effect of phosphate on the physical and microstructural properties of synthetic calcium aluminate cement

The aim of this study was to investigate the synthesis of calcium aluminate cement with and without phosphate additive by combustion synthesis. After preparing the gel from a solution containing aluminum and calcium nitrates and glycine fuel and ammonium dihydrogen Phosphate, its combustion was performed at 400 ° C.  X-ray diffraction pattern and thermal analysis of the combustion sample showed that the sample contains an amorphous phase and requires heat treatment at temperatures to reach the crystalline phases. Calcination were performed at 900 ° C and 1100 ° C for one hour. The results showed that the sample without phosphorus additive contained the main phase CaAl2O4 and in the sample with phosphorus additive contained the main phases CaO.2Al2O3 and Ca3(PO4)2. Final setting time of  samples without phosphorus additive were 242 minutes and with phosphorus additive were 672 minutes.