四水硝酸钙对磷酸钾镁水泥水化硬化的影响

关键字：四水硝酸钙,磷酸钾镁,水泥,水化,硬化

（后勤工程学院 化学与材料工程系，重庆  401311）

    摘要：为了对磷酸钾镁水泥（MKPC）水化温升和凝结时间进行控制，将四水硝酸钙掺入其中，研究了四水硝酸钙对MKPC水化温升、凝结时间及力学性能的影响，并结合XRD、SEM和热分析等分析了四水硝酸钙在MKPC中的作用机理。结果表明：在早期水化过程中，四水硝酸钙将与硼砂反应生成硼酸钙，四水硝酸钙掺量较少时，硼酸钙的含量较少，缓凝效果不足，MKPC凝结时间略微缩短；继续增大四水硝酸钙的掺量，硼酸钙以膜层的方式覆盖在氧化镁表面，阻滞水化反应进行，凝结时间大幅度延长。硼酸钙的生成降低了浆体的流动度和水化产物的生成量，继而对MKPC的力学性能产生负面影响。综合考虑，四水硝酸钙的掺量应控制在4%左右。
    关键词：四水硝酸钙；MKPC；凝结时间；硼砂；硼酸钙
    中图分类号：TU528.31；TQ172.1        文献标识码：A        文章编号：1001-702X（2017）11-0091-05
 

Influence of Calcium Nitrate Terahydrate on magnesium phosphate cement hydration and hardening
ZHAO Sixie，YAN Hua，WANG Hongtao，LI Yuntao，ZHANG Hansong
（Dept. of Chemical and Material Engineering，LEU，Chongqing 401311，China）

    Abstract：In order to regulate hydration temperature rise and setting time of magnesium potassium phosphate cement（MKPC），Calcium Nitrate Terahydrate was added. The effect of Calcium Nitrate Terahydrate on hydration temperature rise，setting time and mechanical properties were investigated，and the influence mechanism of its was explored combining XRD，SEM and thermal analysis microcosmic analysis. The result showed：In early hydration stage，Calcium Nitrate Terahydrate would generate calcium borate by reacting with borax. When the content of Calcium Nitrate Terahydrate is little，the amount of calcium borate was little，causing retarding effect deficiency. So，setting time of MKPC would shorten slightly. Increase content of Calcium Nitrate Terahydrate，calcium borate covering on the surface of magnesia by way of membranous layer，reducing hydration reaction slow and prolonging setting time largely. At the same time，the generation of calcium borate diminish fluidity and amount of hydration products，which have negative impacts on mechanical properties of MKPC. Comprehensively considering，the content of Calcium Nitrate Terahydrate should be controlled within 4%.
    Key words：calcium nitrate terahydrate，magnesium potassium phosphate cement（MKPC），setting time，borax，calcium borate