Abstract: To optimize the service performance of magnesium potassium phosphate cement,magnesium potassium phosphate cement was prepared by sintering magnesium oxide and potassium dihydrogen phosphate with composite retarder.The effects of different n(Mg)∶n(P)(2∶1,3∶1,4∶1) on the microstructure,hydration behavior and mechanical properties of magnesium potassium phosphate cement were systematically studied.The performance differences between magnesium potassium phosphate cement and ordinary Portland cement after high temperature heat treatment were compared and analyzed.The results show that when n(Mg)∶n(P) is 3∶1,the hydration reaction of potassium magnesium phosphate cement is the most sufficient,forming a dense matrix structure,and the compressive strength at room temperature is increased to 44.6 MPa.After heat treatment at a lower temperature,the strength of magnesium potassium phosphate cement is significantly reduced due to the decomposition of potassium struvite,the hydration product of magnesium potassium phosphate cement.After high temperature heat treatment at 1000 ℃,magnesium potassium phosphate cement is sintered to form a dense matrix structure,and its high temperature residual compressive strength tends to be stable.The strength retention rate of residual strength is higher than that of Portland cement,showing better high temperature stability.

Key words: Magnesium potassium phosphate cement, Portland cement, Magnesium phosphorus ratio, High temperature residual strength

摘要： 为优化磷酸钾镁水泥的服役性能,采用复合缓凝剂,烧结氧化镁与磷酸二氢钾制备磷酸钾镁水泥,系统研究了不同n(Mg)∶n(P)(为2∶1、3∶1、4∶1)对磷酸钾镁水泥显微结构、水化行为及力学性能的影响,对比分析了磷酸钾镁水泥与普通硅酸盐水泥高温热处理后性能差异。结果表明:当n(Mg)∶n(P)为3∶1时,磷酸钾镁水泥水化反应最为充分,形成较为致密的基体结构,常温耐压强度提升至44.6 MPa。在较低热处理温度下,由于磷酸钾镁水泥的水化产物钾鸟粪石分解导致强度显著降低,在1 000 ℃高温热处理后,磷酸钾镁水泥烧结形成较致密的基体结构,其常温耐压强度趋于稳定,强度保持率高于硅酸盐水泥的,表现出更优异的高温稳定性。

关键词: 磷酸钾镁水泥, 硅酸盐水泥, 镁磷比, 高温残余强度