氯离子侵蚀圆形截面钢筋混凝土结构耐久性分析

依据质传递原理并考虑混凝土对氯离子的结合能力,建立了氯离子在圆形截面混凝土中的扩散传质方程。通过该方程可以确定钢筋表面氯离子达到临界质量浓度所需的时间,以此确定钢筋锈蚀起始时间。利用有限差分法求解方程,对结果进行了分析,并与基于Fick第二定律的扩散方程的结果比较发现:圆形截面构件钢筋锈蚀开始时间与保护层厚度和截面半径的关系有关;耐久性设计与评估应充分考虑截面曲边效应的影响。

Durability Analysis of Reinforced Concrete Structure with Circular Section under Chlorine Anion Corrosion

An equation of diffusion mass transfer for chlorine anion in reinforced concrete structure with circular section was deduced according to the binding capacity of concrete to chloride ion as well as the principle of mass transfer. In terms of this equation, the time when the chlorine anion concentration on the surface of the reinforcement reaches its concentration threshold was obtained, and then the time of the initiation of chloride-induced reinforcement corrosion was got. The solution of presented equation was derived by the finite difference method, and a conclusion was drawn by analyzing the obtained result in comparison with the result produced from the diffusion equation based on Fick's second law: the initiate time of reinforcement corrosion in concrete structure with circular section is connected with the correlation between cover thickness and section radius. The effect of the section property should be considered during durability designing or evaluating.