【摘要】 磷酸镁水泥（MPC）的镁质原料主要为重烧MgO,由于制备重烧MgO需要高温煅烧，其使用成本和碳排放量过高。氢氧化镁（Mg（OH）₂）的来源丰富，制取成本低廉且无污染、安全环保，如能大量采用对缓解使用成本和碳排放量过高这一问题具有重要意义。因此，本工作使用Mg（OH）₂代替部分重烧MgO,通过X射线衍射、热分析、扫描电镜和能谱分析等测试手段，研究其对MPC工作性能、水化过程、强度发展和微观结构的影响。结果表明，Mg（OH）₂的掺入加快了MPC的水化过程，浆体的流动度降低，凝结时间缩短，本工作通过水玻璃热处理改性等缓凝手段改善其工作性能。随着Mg（OH）₂的掺入，磷酸镁水泥的水化温度和pH值显著降低，水化28 d后的K-鸟粪石（K-struvite）结晶数量增多，抗压强度随Mg（OH）₂含量的增加而降低，当Mg（OH）₂掺量在50%以内时，其后期强度下降在15%的范围内，随Mg（OH）₂掺量增大，更多的水化产物是由Mg（OH）₂反应形成的，当Mg（OH）₂掺量为66.6%时，重烧MgO的反应率由平均值22%降低至7%。总而言之，采用大掺量Mg（OH）₂制备磷酸镁水泥具有可行性且能确保材料的后期力学性能满足工程应用的要求，对降低磷酸镁水泥使用成本和碳排放具有潜在的应用前景。更多还原

【Abstract】 The magnesium raw material for magnesium phosphate cement（MPC） is mainly dead-burned MgO. However, the high-temperature calcination required for producing dead-burned MgO results in high costs and excessive carbon emissions. magnesium hydroxide（Mg（OH）₂） is abundant, has low production costs, and is environmentally safe and pollution-free. Mg（OH）₂ is a rich source of low-cost, non-polluting, safe and environmentally friendly, which is of great significance to alleviate the problem of high cost of use and carbon emissions if it can be adopted in large quantities. Therefore, in this work, Mg（OH）₂ was used instead of partially dead-burned MgO, by means of tests such as X-ray diffraction, thermal analysis, scanning electron microscopy and energy spectrum analysis, the effects on workability, hydration process, strength development and microstructure were investigated. The results showed that the incorporation of Mg（OH）₂ accelerated the hydration process of MPC, the fluidity of the slurry was reduced and the setting time was shortened. In this paper, the working properties are improved by retardation means such as water glass heat treatment modification. The hydration temperature and pH of magnesium phosphate cement decreased significantly with the incorporation of Mg（OH）₂, increased number of K-struvite crystals in the later 28 d, compressive strength decreases with increasing Mg（OH）₂ content. When Mg（OH）₂ is doped within 50%, its late strength decreases in the range of 15%, with the increase of Mg（OH）₂ doping, more hydration products are formed by the reaction of Mg（OH）₂. When Mg（OH）₂ doping accounted for 66.6%, the reactivity of dead-burned MgO was reduced from an average value of 22% to 7%. In conclusion, the preparation of magnesium phosphate cement with large amount of Mg（OH）₂ is feasible and can ensure that the later mechanical properties of the material can meet the requirements of engineering applications. It has potential applications for reducing the cost of magnesium phosphate cement use and carbon emissions.更多还原