干湿交替区域混凝土中氯离子分布随高程的变化规律

Chloride ion distribution in concrete of dry-wet cycling region along elevated altitude

在干湿交替区域混凝土中氯离子的输运属于在孔隙非饱和状态下离子浓度扩散和对流耦合的渗透.传质机理分析表明,混凝土内部孔隙的饱和度、混凝土表面蒸发速率与干湿循环制度是影响非饱和状态下氯离子分布的主要因素;干湿交替区域混凝土中氯离子分布规律取决于不同海拔高度处环境因素的变化规律.实际工程检测结合基于机理分析的数值模拟结果表明,随高程增加,氯离子侵蚀程度呈先加剧后缓解的趋势,在某一高程处氯离子侵蚀达到极值,该区域应该作为混凝土结构耐久性设计和维护的关键部位.

The flow of chloride ions in the concrete of dry-wet cycling region is the combining of diffusion and advection. Mechanical analysis of mass transfer revealed that the saturation of pore solution in concrete, the evaporation rate of pore solution in concrete surface, and the dry-wet cycling regime are the main three factors affecting the unsaturated flow of chloride ion in concrete. The changing of environmental factors along elevated altitude above sea surface decides the distribution law of chloride ingress in the dry-wet cycling region. Results of both the detection and the numerical simulation based on mechanical analysis revealed that with the elevated altitude increases, the chloride ingress aggravates firstly and alleviates finally, and the peak value appears in a certain region which is the key region of durability design and maintenance of concrete structures.