Effects of magnesium phosphate cement proportions on paste properties

Magnesium phosphate cement is a rapid-setting alternative cement typically used as a quick repair material. There is currently limited research on the properties of magnesium phosphate cement when varying the proportions of its main component ingredients. Setting times, compressive strengths, and flow values are strongly affected by mixture characteristics such as the magnesia to phosphate molar ratio, water to cementitious materials ratio, chosen phosphate component and replacement rates, set retarder type, set retarder dosage, fly ash type (class C or class F), and fly ash replacement rate. This study found that lower magnesia to phosphate molar ratio, higher water to cementitious materials ratio, higher set retarder dosages, and inclusion of class C fly ash provided longer setting times and higher flow values. Higher magnesia to phosphate molar ratio, lower water to cementitious materials ratio, lower set retarder dosages, and no addition of fly ash provided higher compressive strengths. Many of the examined parameters also affected the thixotropic nature of this material. This work should aid in future studies seeking to develop non-proprietary magnesium phosphate cement formulations.