杂散电流对滨海钢筋混凝土结构的腐蚀机理及劣化模型研究

This research focuses on durability of reinforced concrete (RC) structure in coastal environment. Utilizing a self-designed bipolar power system for simulating stray current supply, the stray current induced RC corrosion mechanisms and the corresponding deterioration model will be studied. The aim of the project is to explore the transport behavior of chloride in concrete and to develop the transport model under action of stray current. Moreover, effects of both non-zero amplitude and alternating anodic and catholic reactions on the time dependent microstructure and chemical composition will be analyzed. Meanwhile, the depassivation mechanism is investigated with combining action both chloride ions and stray current. And, the range of chloride threshold concentration in the presence of stray current will be proposed. Furthermore, the model of corrosion efficient by stray current is established by considering the condition for anodic and catholic reaction. By combing the crucial factors mentioned above, the deterioration model for reinforced concrete under stray current is proposed. Through this project, the corrosion mechanism and degradation development of reinforced concrete under stray current can be investigated, and the scientific evidence for the safe operation of reinforced concrete structure in railway transportation can then be provided.

本项目以滨海钢筋混凝土结构的耐久性为背景，基于自行设计的双极性杂散电流模拟系统，研究滨海钢筋混凝土结构的杂散电流腐蚀机理及劣化模型。主要研究目标为阐明杂散电流作用下氯离子在混凝土中的迁移规律，并建立相应的氯离子电迁移模型；分析杂散电流非零均值以及阳极、阴极反应交替变换对钢筋-混凝土界面微观结构及化学组成的影响规律；探讨杂散电流和氯离子共同作用下混凝土中钢筋的脱钝机理，提出杂散电流工况下氯离子临界浓度的一般取值范围；分析各阳极、阴极反应的发生条件，建立杂散电流钢筋腐蚀效率计算模型；结合氯离子电迁移、钢筋-混凝土界面演变及钢筋腐蚀效率等关键因素，构建钢筋混凝土杂散电流腐蚀劣化模型。通过项目研究可充分揭示钢筋混凝土杂散电流腐蚀机理以及劣化发展规律，为保障轨道交通钢筋混凝土主体结构的安全服役提供科学依据。

本项目以滨海钢筋混凝土结构耐久性为背景，基于自行设计的双极性杂散电流模拟电源，对滨海钢筋混凝土结构杂散电流腐蚀机理及劣化模型进行了研究。获得的主要成果如下：1）设计了杂散氯离子电迁移装置SC-RCM和SC-ASTM，构建了杂散电流作用下的氯离子电迁移公式，并通过氯离子电迁移试验，获得了折减系数K经验取值；2）借助线性极化（LPR）、扫描电镜及能谱（SEM/EDS）和X射线衍射（XRD）等测试方法，阐述了杂散电流与氯离子共同作用下砂浆中钢筋的腐蚀机理，分析了钢筋-混凝土界面演变规律；3）采用XCT技术，研究了杂散电流作用下混凝土中钢筋锈蚀随时间的变化规律，建立了杂散电流场环境下混凝土结构钢筋的锈蚀量计算模型。该锈蚀量计算模型可用于杂散电流场中的混凝土结构钢筋锈蚀量的预测。项目研究成果初步揭示了钢筋混凝土杂散电流腐蚀机理以及劣化发展规律，可为保障轨道交通钢筋混凝土结构安全服役提供科学依据。