Magnesium oxychloride cement (MOC) possesses some excellent characteristics, which can be used as oil well cement, to deal with the complex environmental conditions in oil and gas wells. However, the water resistance property of MOC is poor. In this study, a new type of magnesium oxychloride cement (MOC) with improved water resistance was developed by modifying the pore structure of pure MOC using hydrophobic admixtures. To assess the performance of the new MOC, a range of tests were performed, including compressive strength, softening coefficient, capillary water absorption, pore size distribution, mineral composition and microstructure analysis. The results showed that the pore size distribution of the MOC was altered from a large pore-dominant structure to a small pore-dominant one. The hydrophobic admixture and the gel substance formed on the strength-providing phases prevented them from water erosion, resulting in enhanced strength and water resistance. This new type of MOC has the potential to be used in challenging environments, such as oil and gas wells and underwater structures.

氯氧化镁水泥（MOC）具有一些优异的特性，可作为油井水泥，应对油气井复杂的环境条件。但MOC的耐水性能较差。在这项研究中，通过使用疏水性外加剂改变纯MOC的孔隙结构，开发了一种具有改进耐水性的新型氯氧化镁水泥（MOC）。为了评估新型 MOC 的性能，进行了一系列测试，包括抗压强度、软化系数、毛细管吸水率、孔径分布、矿物成分和微观结构分析。结果表明，MOC的孔径分布从以大孔为主的结构转变为以小孔为主的结构。疏水性混合物和在提供强度的相上形成的凝胶物质防止它们受到水的侵蚀，从而增强了强度和耐水性。这种新型 MOC 有潜力用于具有挑战性的环境，例如油气井和水下结构。