Time/depth dependent diffusion and chemical reaction model of chloride transportation in concrete
Time/depth dependent diffusion and chemical reaction model of chloride transportation in concrete
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DOI：
10.1016/j.apm.2011.07.053
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发表时间：
2012-03
影响因子：
5
通讯作者：
Yung-Ming Sun;M. Liang;Ta-Peng Chang
中科院分区：
文献类型：
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作者：
Yung-Ming Sun;M. Liang;Ta-Peng Chang
本研究的重点是控制氯离子进入混凝土结构的物理和化学过程。本文提出了一个确定随时间和深度变化的氯离子扩散系数的扩散反应模型的解析解，该模型考虑了氯离子的扩散过程和结合机制同时发生。基于Fick扩散第二定律和不可逆一级化学反应的数学描述，建立了氯离子扩散过程的扩散-反应模型，精确描述了氯离子扩散过程的扩散机理。当考虑化学反应时，自由氯离子浓度缓慢降低，因为一些自由氯离子已经与水泥浆反应，使得扩散系数也同时降低。扩散-反应模型预测的使用寿命比不考虑氯化物扩散过程中化学反应影响的总氯化物扩散模型和自由氯化物扩散模型更长。
This study focuses on the physical and chemical processes that control the transport of chloride ions into concrete structures. An analytical solution of a diffusion reaction model is presented for determining the time/depth dependent chloride diffusivities considering both diffusion process and binding mechanism of chloride occur simultaneously. The diffusion-reaction model, which is based on the Fick’s second law of diffusion and a mathematical formulation for an irreversible first-order chemical reaction, is used to precisely describe the diffusion mechanism of chloride diffusion process. When the chemical reaction is considered, the free chloride concentration is slowly reduced since some of the free chloride ions have reacted with cement paste such that the diffusion coefficient is also reduced simultaneously. The diffusion-reaction model predicts a longer service life than the total and free chloride diffusion models that do not consider the effect of the chemical reaction during the chloride diffusion process.