偏高岭土改性磷酸镁水泥

Magnesium Phosphate Cement Modified by Metakaolin

磷酸镁水泥具有快硬早强特性,但使用缓凝剂延长凝结时间会导致早期强度下降。采用偏高岭土部分替代氧化镁对磷酸镁水泥进行改性,研究了偏高岭土取代量对磷酸镁水泥砂浆凝结时间、水化热、小时强度和粘结强度的影响,并采用扫描电镜对水化产物进行了分析。结果表明：偏高岭土部分取代氧化镁可显著延长磷酸镁水泥砂浆凝结时间,且大幅提高其1 h强度和粘结强度;偏高岭土中的活性Al2O3参与反应并形成AlH3（PO4）2·H2O和AlPO4等非晶态凝胶,有效改善了其力学性能。

Magnesium phosphate cement possesses（MPC） the characteristics of fast setting and high early strength. The addition of retarders can prolong the setting time in the case of reducing the early strength. MPC was modified by using metakaolin partially instead of magnesia. The effect of metakaolin replacement amount on the setting time, hydration heat and mechanical strength was investigated, and the hydration products were analyzed by scanning electron microscopy and X-ray diffraction. The results show that partially-replacement of metakaolin can prolong the setting time and improve the 1 h strength and bonding strength of magnesium phosphate cement. The microstructure indicates that active Al2O3 in metakaolin participates in the reaction and forms amorphous gel of AlH3（PO4）2·H2O and AlPO4, which can effectively improve the mechanical properties.