Factors influencing properties of phosphate cement-based binder for rapid repair of concrete11This paper was originally submitted to Advanced Cement Based Materials. The paper was received at the Editorial Office of Cement and Concrete Research on 19 August 1998 and accepted in final form 2 December 1998.

Phosphate cement-based binders were prepared by mixing MgO powder (M) with NH4H2PO4 powder (P) and borax powder (B). Effects of various factors including the amount of retarder B, P/M ratio, fineness of M, and addition of fly ash and environment temperature on setting time and mechanical properties of magnesium phosphate cement-based binder (MPB) were investigated. Results showed that the setting time and early strength of MPB were mainly controlled by the amount of B, the fineness of M, and temperature, but that these factors had little influence on the final strength of the binder. It is interesting that MPB sets and hardens within 1 h, even at −10 °C. A setting and hardening mechanism on MPB is proposed.