An Experimental Investigation on the Effects of Limestone Fines in Manufactured Sands on the Performance of Magnesia Ammonium Phosphate Mortar

Magnesium ammonium phosphate cement (MAPC) prepared with dihydrogen (NH4H2PO4, ADP) and dead-burned oxide (MgO) is a new type of rapid patch repair material for concrete structures. In order to reduce the costs MAPC mortar, manufactured limestone sands, being more widely-available resource lower cost, was investigated in this study as an alternative quartz sands preparation mortar. The fines were found be key factor that influences properties mortar by causing bubbling volume expansion before hardening. As result, mechanical strength decreased increasing content due increased porosity. According microstructure analysis, mechanism these negative effects can inferred reaction between ADP gas generation CO2 NH3. This mainly occurred during short period setting while most remained unreactive hardened Based on above detailed experimental findings sand paper pointed out effective defoaming methods inhibiting utilization high performance