Tavares Fabiano, Andrade Carmen
Department of Mechanics of Continuum Media and Structures, Polytechnical High School of Cordoba, Campus Rabanales, 14031 Cordoba, Spain.
International Center for Numerical Methods in Engineering (CIMNE), 28010 Madrid, Spain.
Materials (Basel). 2022 Feb 15;15(4):1426. doi: 10.3390/ma15041426.
The chloride penetration is usually modelled through the application of a solution of Fick's second law of diffusion, based on the assumption of semi-infinite boundary conditions. However, the presence of the bars, on whose surface the chlorides accumulate, makes this assumption incorrect. As the time progresses, the chlorides in the steel/concrete interface increase in concentration more than the chlorides overpassing the bar position without obstacles. This circumstance, although previously studied, has not been introduced in common practice, in spite of it supposes early reaching of the chloride threshold. The study in this paper shows a deterministic analysis of the chloride diffusion process by the finite element method (FEM) which numerically solves Fick's second law, taking into account the accumulation of the chlorides on the bar surface. Several examples are calculated and factors between the finite/semi-infinite solutions are given. These factors depend on the cover depth and the diffusion coefficient, and with less importance, on the diameter of the bar, which make it unfeasible to propose a general trend.
氯离子渗透通常是通过应用基于半无限边界条件假设的菲克第二扩散定律的解来建模的。然而，钢筋的存在会使氯化物在其表面积聚，这使得该假设不正确。随着时间的推移，钢筋/混凝土界面处的氯化物浓度增加得比越过无障碍物的钢筋位置的氯化物浓度更多。尽管此前已对此情况进行过研究，但尽管它意味着氯离子阈值的提前达到，却尚未在实际应用中引入。本文的研究通过有限元方法（FEM）对氯离子扩散过程进行了确定性分析，该方法通过数值求解菲克第二定律，同时考虑了氯化物在钢筋表面的积聚。计算了几个示例，并给出了有限/半无限解之间的系数。这些系数取决于保护层厚度和扩散系数，而钢筋直径的影响较小，这使得无法提出一个通用的趋势。
