Effect of raw materials and proportion on mechanical properties of magnesium phosphate cement

Abstract

Magnesium phosphate cement (MPC) cementitious material is a phosphate cement-based material with strength formed by a serious of acid-base neutralization reactions among magnesium oxide, phosphate retarder and water, which has a high early strength and a broad application prospect in the field of pavement rehabilitation. This review collects and organizes the latest progress in the field of research on the influencing factors of mechanical properties of magnesium phosphate cementitious materials worldwide in recent years, and discusses the possibilities of application in airport engineering.The type of phosphate has a great influence on the reaction products, and the strength of the reaction products of ammonium salt is higher. Borax is the most commonly used retarder, and the retarding effect is related to the ratio of boron to magnesium. However, borax retarders have an adverse effect on the strength of MPC. In terms of the influence of mineral admixtures on the properties of MPC, fly ash, silica fume and metakaolin, as common mineral admixtures, have a positive influence on the mechanical properties of MPC, but the mechanism and degree of the influence of the three materials on the strength of MPC are slightly different; Aggregates can also improve the volume stability and mechanical properties of MPC by forming skeleton structure and slowing down the exothermic reaction. In fiber reinforced MPC matrix, steel fiber is the most widely used and the bonding performance between special-shaped steel fiber and MPC matrix is higher than that of straight fiber; basalt fiber has also been proved to be used to improve the mechanical properties of MPC system.