Preparation of Magnesium Ammonium Phosphate Mortar by Manufactured Limestone Sand Using Compound Defoaming Agents for Improved Strength and Impermeability

Magnesium ammonium phosphate cement (MAPC) mortar has recently risen up as high performance rapid repair material for concrete structures. But costs of the raw materials limit its restoration and maintenance projects on a wide application range. This study proposes use manufactured limestone sand with lower cost wider range sources in replacement quartz fine aggregates to produce MAPC mortar. However, fines were initially found have negative effects mortar, causing significant blistering volume expansion decreased compressive strength interfacial bonding strength. To minimize these effects, polyether modified silicone (PMS) defoamer compound mineral admixtures Portland silica fume investigated effectiveness reducing improving other properties Results showed that PMS new defoaming formula effectively reduced from 7.92% 0.91%. The significantly improved by over 34% 60% respectively. Moreover, this improvements water-tight resistance chloride penetration. According mercury intrusion porosimetry (MIP) analysis, total porosity after treatment was about 40% pore structure also be finer harmful macropores. Overall, sands turned out feasible economic approach promoting filed