Huang Qing, Wang Su, Du Yongsheng, Yin Zhigang, Chen Bing, Zhang Jie, Zheng Weixin
School of Materials Science and Engineering, Shaanxi University of Technology, Hanzhong 723001, China.
National and Local Joint Engineering Laboratory for Slag Comprehensive Utilization and Environmental Technology, Shaanxi University of Technology, Hanzhong 723000, China.
Materials (Basel). 2024 Sep 30;17(19):4828. doi: 10.3390/ma17194828.
This study investigates the effects of phosphoric acid (HPO), potassium dihydrogen phosphate (KHPO) and sodium dihydrogen phosphate (NaHPO) admixtures on the setting time, compressive strength and water resistance of magnesium oxychloride cement (MOC). MOC samples incorporating different admixtures are prepared, and their hydration products and microstructures are studied via X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicate that the addition of HPO, KHPO and NaHPO reduces the initial and final setting times and decreases the compressive strength. However, the compressive strength of MOC is higher than 30.00 MPa with the addition of 2.0 wt.% phosphoric acid and its phosphate after 14 days of air curing. The water resistance of modified MOC slurries is significantly improved. The softening coefficient of MOC with 2.0 wt.% HPO is 1.2 after 14 days of water immersion, which is 3.44 times higher than that of the neat MOC. The enhancement in water resistance is attributed to the formation of amorphous gel facilitated by HPO, KHPO and NaHPO. Furthermore, the improvement in water resistance is manifested as HPO > KHPO > NaHPO.
本研究考察了磷酸（H₃PO₄）、磷酸二氢钾（KH₂PO₄）和磷酸二氢钠（NaH₂PO₄）外加剂对氯氧镁水泥（MOC）凝结时间、抗压强度和耐水性的影响。制备了掺入不同外加剂的MOC样品，并通过X射线衍射（XRD）和扫描电子显微镜（SEM）研究了它们的水化产物和微观结构。结果表明，添加H₃PO₄、KH₂PO₄和NaH₂PO₄会缩短初凝和终凝时间，并降低抗压强度。然而，在空气养护14天后，添加2.0 wt.%磷酸及其磷酸盐时，MOC的抗压强度高于30.00 MPa。改性MOC浆料的耐水性显著提高。浸泡14天后，含2.0 wt.% H₃PO₄的MOC的软化系数为1.2，是纯MOC的3.44倍。耐水性的提高归因于H₃PO₄、KH₂PO₄和NaH₂PO₄促进形成的无定形凝胶。此外，耐水性的提高表现为H₃PO₄＞KH₂PO₄＞NaH₂PO₄。
