Abstract

Practical observations demonstrate that the corrosion deterioration of numerous reinforced concrete structures is due to the combination of carbonation and chloride ingress. However, the comprehensive combined model developed directly based on the coupling mechanism of them is very complicated. This article presents a simplified model to describe the transport of chloride ions with carbonation by introducing the Stefan condition, which is mainly used for the mathematical modelling of boundary movement caused by phase transformation in thermodynamics. Meanwhile, the influence function of carbonation on the diffusion coefficient of chloride ion is also re-discussed. An empirical formula is fitted directly according to the mix proportions of concrete, which can greatly reduce the computational cost. Then, an intuitively expressed formula of chloride concentration distribution under the influence of carbonation can be solved. Ultimately, its prediction accuracy is verified by two experiments.

摘要

实际观察表明，许多钢筋混凝土结构的腐蚀恶化是由于碳化和氯化物侵入的结合。然而，直接基于它们的耦合机制开发的综合组合模型非常复杂。本文通过引入 Stefan 条件，提出了一个简化的模型来描述氯离子在碳酸化过程中的迁移，该条件主要用于热力学中相变引起的边界运动的数学建模。同时，也重新讨论了碳酸化作用对氯离子扩散系数的影响作用。直接根据混凝土配合比拟合经验公式，可大大降低计算成本。然后，可以得到一个直观表达的碳酸化作用下氯化物浓度分布的公式。最终通过两次实验验证了其预测的准确性。