Luo Zhiyuan, Yu Hongfa, Ma Haiyan, Tan Yongshan, Wu Chengyou, Sun Jingnan, Wang Xiaoming, Wu Peng
School of Civil Engineering, Qinghai University, Xining 810016, China.
College of Civil Aviation, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China.
Materials (Basel). 2025 Apr 12;18(8):1769. doi: 10.3390/ma18081769.
Salt lakes and the surrounding saline soils distributed across northwestern China and Inner Mongolia impose severe physicochemical corrosion on cement-based concrete. Understanding the corrosion products and mechanisms are crucial scientific and technological factors in ensuring the durability and service life of concrete structures in these regions. In this study, various analytical techniques-including X-ray diffraction, thermogravimetric-differential thermal analysis, X-ray fluorescence, and scanning electron microscopy coupled with energy-dispersive spectroscopy-were employed to systematically analyze the corrosion products of ordinary Portland cement (OPC) and high-performance concrete (HPC) specimens after eight years of field exposure in the Qarhan Salt Lake area of Qinghai. The study provided an in-depth understanding of the physicochemical corrosion mechanisms involved. The results showed that, after eight years of exposure, the corrosion products comprised both physical corrosion products (primarily sodium chloride crystals), and chemical corrosion products (associated with chloride, sulfate, and magnesium salt attacks). A strong correlation could be observed between the chemical corrosion products and the strength grade of the concrete. In C25 OPC, the detected corrosion products included gypsum, monosulfate-type calcium sulfoaluminate (AFm), Friedel's salt, chloro-ettringite, brucite, magnesium oxychloride hydrate 318, calcium carbonate, potassium chloride, and sodium chloride. In C60 HPC, the identified corrosion products included Kuzel's salt, Friedel's salt, chloro-ettringite, brucite, calcium carbonate, potassium chloride, and sodium chloride. Among them, sulfate-induced corrosion led to the formation of gypsum and AFm, whereas chloride-induced corrosion resulted in chloro-ettringite and Friedel's salt. Magnesium salt corrosion contributed to the formation of brucite and magnesium oxychloride hydrate 318, with Kuzel's salt emerging as a co-corrosion product of chloride and sulfate attacks. Furthermore, a conversion phenomenon was evident between the sulfate and chloride corrosion products, which was closely linked to the internal chloride ion concentration in the concrete. As the chloride ion concentration increased, the transformation sequence of sulfate corrosion products occurred in the following order: AFm → Kuzel's salt → Friedel's salt → chloro-ettringite. There was a gradual increase in chloride ion content within these corrosion products. This investigation into concrete durability in salt-lake ecosystems offers technological guidance for infrastructure development and material specification in hyper-saline environments.
分布于中国西北和内蒙古地区的盐湖及其周边盐碱土，对水泥基混凝土造成严重的物理化学腐蚀。了解腐蚀产物及机制是确保这些地区混凝土结构耐久性和使用寿命的关键科技因素。本研究采用多种分析技术，包括X射线衍射、热重-差热分析、X射线荧光以及扫描电子显微镜联用能谱分析，对青海察尔汗盐湖地区野外暴露8年后的普通硅酸盐水泥（OPC）和高性能混凝土（HPC）试件的腐蚀产物进行了系统分析。该研究深入了解了其中涉及的物理化学腐蚀机制。结果表明，暴露8年后，腐蚀产物既有物理腐蚀产物（主要为氯化钠晶体），也有化学腐蚀产物（与氯离子、硫酸根离子和镁盐侵蚀有关）。化学腐蚀产物与混凝土强度等级之间存在很强的相关性。在C25 OPC中，检测到的腐蚀产物包括石膏、单硫酸盐型硫铝酸钙（AFm）、Friedel盐、氯铝酸钙石、水镁石、水合氯氧化镁318、碳酸钙、氯化钾和氯化钠。在C60 HPC中，鉴定出的腐蚀产物包括Kuzel盐、Friedel盐、氯铝酸钙石、水镁石、碳酸钙、氯化钾和氯化钠。其中，硫酸根离子引起的腐蚀导致石膏和AFm的形成，而氯离子引起的腐蚀产生氯铝酸钙石和Friedel盐。镁盐腐蚀促使水镁石和水合氯氧化镁318的形成，Kuzel盐是氯离子和硫酸根离子共同侵蚀的产物。此外，硫酸根离子和氯离子腐蚀产物之间存在明显的转化现象，这与混凝土内部氯离子浓度密切相关。随着氯离子浓度增加，硫酸根离子腐蚀产物的转化顺序为：AFm→Kuzel盐→Friedel盐→氯铝酸钙石。这些腐蚀产物中的氯离子含量逐渐增加。这项对盐湖生态系统中混凝土耐久性的研究，为高盐环境下的基础设施建设和材料选型提供了技术指导。
