Effect of sodium phosphate on properties and internal porosity of ceramsite prepared by sintering red mud

Using sodium phosphate as bubble stabilizer, the effect of weight ratio of sodium phosphate on properties of ceramisite, prepared mianly from sintering red mud, was investigated in the study. Subsequently, Main crystalline minerals were analyzed by XRD, and internal porosity uniform were observed by SEM. The results showed both bulk density and water absorption rate (WAR) were slightly affetced by sodium phosphate, while cylinder compressive strength (CCS) was significantly influenced. Under the weight ratio of 4% sodium phosphate, ceramisite with bulk density of 1.13g/cm³, WAR of 3.92% and CCS of 9.86MPa was obtained The internal porosity uniform of sintered ceramisites was obviously improved by sodium phosphate, but was damaged if excessive sodium phosphate was added to preparting materials, based on SEM. Crystalline phases in ceramisite mainly was gehlenite, and its formation was promoted by sodium phosphate based on XRD.