Factors influencing properties of phosphate cement-based binder for rapid repair of concrete

Phosphate cement-based binders were prepared by mixing MgO powder (M) with NH4H2PO4 powder (P) and borax powder (B). Effects of various factors includ ing the amount of retarder B, P/M ratio, fineness of hi, and addition of fl y ash and environment temperature on setting time and mechanical properties of magnesium phosphate cement-based binder (MPB) were investigated. Result s showed that the setting time and early strength of MPB were mainly contro lled 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 in teresting that MPB sets and hardens within 1 h, even at -10 degrees C. A se tting and hardening mechanism on MPB is proposed. (C) 1999 Elsevier Science Ltd. All rights reserved.