Luo Xuanzhang, Lai Zhenyu, Liu Zhi, Xiao Rui, Chen Jiawei, Lu Zhongyuan, Lv Shuzhen, Wang Jin
State Key Laboratory of Environmental-Friendly Energy Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China.
Materials (Basel). 2022 Dec 18;15(24):9047. doi: 10.3390/ma15249047.
As a rapid repair material, magnesium phosphate cement (MPC) can be used under various environmental temperature conditions, but different temperatures significantly impact its strength and working performance. In this study, based on the surface modification of magnesium oxide, the working and mechanical properties of samples were investigated at an ambient temperature of -5 °C, and the hydration properties and microstructure of MPC were investigated using X-ray diffraction (XRD), thermogravimetric analysis (TG), mercury-in-pressure (MIP), and scanning electron microscopy (SEM). The results show that the modified magnesium oxide at a negative temperature prolongs the setting time of MPC from 10 min to more than 30 min, and fluidity can still be maintained or increased after half an hour. From 1 d to 28 d, the compressive strength growth rate of the reference group was 257.0% compared to 723.8% for the 10 wt% water-glass-modified MgO sample. K-struvite transformed from a blocky growth to a needle-like growth with the modified sample filling the pores and cracks inside the matrix. Compared with the unmodified sample, MPC's porosity decreased from 9.62% to 9.23% for 10 wt% water-glass-modified MgO. Therefore, the surface modification of magnesium oxide not only prolonged the setting time but also further benefited mechanical performance, which provides the prerequisites for MPC construction in negative-temperature environments.
作为一种快速修复材料，磷酸镁水泥（MPC）可在各种环境温度条件下使用，但不同温度会对其强度和工作性能产生显著影响。本研究基于氧化镁的表面改性，在环境温度为-5°C的条件下研究了样品的工作性能和力学性能，并使用X射线衍射（XRD）、热重分析（TG）、压汞法（MIP）和扫描电子显微镜（SEM）研究了MPC的水化性能和微观结构。结果表明，负温下改性氧化镁使MPC的凝结时间从10分钟延长至30分钟以上，半小时后流动性仍可保持或增加。从1天到28天，参考组的抗压强度增长率为257.0%，而10wt%水玻璃改性MgO样品的抗压强度增长率为723.8%。K-鸟粪石从块状生长转变为针状生长，改性样品填充了基体内部的孔隙和裂缝。与未改性样品相比，10wt%水玻璃改性MgO使MPC的孔隙率从9.62%降至9.23%。因此，氧化镁的表面改性不仅延长了凝结时间，还进一步提升了力学性能，这为MPC在负温环境下施工提供了前提条件。
