Chang Chenggong, An Lingyun, Zheng Weixin, Wen Jing, Dong Jinmei, Yan Fengyun, Xiao Xueying
State Key Laboratory of Advanced Processing and Recycling of Non-Ferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China.
Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lake, Chinese Academy of Sciences, Xining 810008, China.
Materials (Basel). 2021 Dec 20;14(24):7880. doi: 10.3390/ma14247880.
Aiming at the problem that ordinary cement concrete is subjected to damage in heavy saline soil areas in China, a new type of magnesium oxychloride cement concrete is prepared by using the gelling properties of magnesium oxychloride cement in this study, and the erosion resistance of the synthesized magnesium oxychloride cement concrete in concentrated brine of salt lakes is studied through the full immersion test. The effects of concentrated brine of salt lakes on the macroscopic, microscopic morphology, phase composition and mechanical properties of magnesium oxychloride cement concrete are investigated by means of macro-morphology, erosion depth, SEM, XRD and strength changes. The salt erosion resistance mechanism of magnesium oxychloride cement concrete is revealed. The results demonstrate that under the environment of full immersion in concentrated brine of salt lakes, there is no macroscopic phenomenon of concrete damage due to salt crystallization, and the main phase composition is basically unchanged. The microscopic morphology mostly changes from needle-rod-like to gel-like. Due to the formation of a new 5·1·8 phase on the surface layer and the increase in compactness, its compressive strength has a gradual increase trend. Based on the engineering application of magnesium oxychloride cement concrete, it is further confirmed that magnesium oxychloride cement concrete has excellent salt erosion resistance and good weather resistance, which provides theoretical support for future popularization and application.
针对我国重盐碱土地区普通水泥混凝土遭受破坏的问题，本研究利用氯氧镁水泥的胶凝性能制备了一种新型氯氧镁水泥混凝土，并通过全浸泡试验研究了合成的氯氧镁水泥混凝土在盐湖浓卤水中的抗侵蚀性能。借助宏观形貌、侵蚀深度、扫描电子显微镜（SEM）、X射线衍射仪（XRD）及强度变化等手段，研究了盐湖浓卤水对氯氧镁水泥混凝土宏观、微观形貌、物相组成及力学性能的影响。揭示了氯氧镁水泥混凝土的抗盐侵蚀机理。结果表明，在盐湖浓卤水全浸泡环境下，混凝土未出现因盐结晶而导致的宏观破坏现象，主要物相组成基本不变。微观形貌大多由针棒状变为凝胶状。由于表层形成了新的5·1·8相且密实度增加，其抗压强度呈逐渐上升趋势。基于氯氧镁水泥混凝土的工程应用，进一步证实了氯氧镁水泥混凝土具有优异的抗盐侵蚀性能和良好的耐候性，为今后的推广应用提供了理论支撑。
