This article investigated the influence of low-grade bauxite (LG-bauxite) on the properties of magnesium phosphate cement (MPC), which were explored by testing the properties of the fresh mixture (fluidity, setting time, and temperature evolution), measuring the strengths, analyzing the hydrates and observing the microstructure. With the successive additions of LG-bauxite, the fluidity continued to increase to a value of 267 mm, and the setting time was prolonged from 13 min to 26 min. The use of LG-bauxite also improved the mechanical properties of hardened MPC samples, and the group containing 10% LG-bauxite yielded the highest compressive strength of 91.2 MPa at 28 days. In addition, by the technique of X-ray diffraction (XRD), thermogravimetric analysis (DTA-TGA), scanning electron microscopy (SEM) and backscattered electron image (BSE) equipped with energy dispersive spectrometer (EDS), the micro-analyses for the MPC pastes was carried out. The obtained results all confirmed the pore-filling effect of LG-bauxite in MPC system and illustrated the formation of new phases, which was thought to be the alumina phosphate hydrate and some aluminosilicate gels. The fresh MPC slurry blended with LG-bauxite exhibited a lower exothermic reaction intensity and a slower hardening stage, which showed that it could be used as a kind of quick repair material.

本文研究了低品位铝土矿（LG-铝土矿）对磷酸镁水泥（MPC）性能的影响，通过测试新鲜混合物的性能（流动性，凝固时间和温度变化），并通过测量强度，分析水合物并观察微观结构。随着LG-铝土矿的连续添加，流动性继续增加至267mm的值，并且凝固时间从13分钟延长至26分钟。LG-铝土矿的使用还改善了硬化的MPC样品的机械性能，含有10％LG-铝土矿的组在28天时产生的最高抗压强度为91.2 MPa。此外，通过X射线衍射（XRD）技术，热重分析（DTA-TGA），扫描电子显微镜（SEM）和配备能量色散光谱仪（EDS）的背散射电子图像（BSE），对MPC浆料进行了微观分析。所得结果均证实了LG-铝土矿在MPC体系中的孔隙填充作用，并说明了新相的形成，该相被认为是水合磷酸铝和一些硅铝酸盐凝胶。与LG铝土矿共混的新鲜MPC浆料放热反应强度较低，硬化阶段较慢，表明可以用作快速修复材料。被认为是磷酸铝水合物和一些硅铝酸盐凝胶。与LG铝土矿共混的新鲜MPC浆料放热反应强度较低，硬化阶段较慢，表明可以用作快速修复材料。被认为是磷酸铝水合物和一些硅铝酸盐凝胶。掺有LG-铝土矿的新鲜MPC浆料放热反应强度较低，硬化阶段较慢，表明可以用作快速修复材料。