Meso-scale modeling of chloride diffusion in concrete with consideration of effects of time and temperature
Meso-scale modeling of chloride diffusion in concrete with consideration of effects of time and temperature
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DOI：
10.3882/j.issn.1674-2370.2009.03.006
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发表时间：
2009-09
影响因子：
4
通讯作者：
Licheng Wang;T. Ueda
中科院分区：
文献类型：
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作者：
Licheng Wang;T. Ueda
摘要建立了一个细观桁架网络模型来预测氯离子在混凝土中的扩散。该模型将混凝土视为由砂浆基质、骨料以及砂浆基质和骨料之间的界面过渡区组成的三相复合材料。只需细集料的水灰比和体积分数，就可以解析地确定氯化物在砂浆和ITZ中的扩散系数。Fick扩散第二定律被用作氯离子在均匀介质(例如砂浆)中扩散的控制方程；它被离散化并应用于桁架网络模型。给出了基于扩散定律和混凝土细观组合结构的桁架网络模型的求解过程。此外，还考虑了氯离子在砂浆中的扩散系数和ITZ与暴露时间和温度的关系，以说明它们对氯离子扩散系数的影响。数值结果表明，暴露时间和环境温度对氯离子在混凝土中的扩散速率有重要影响。细观桁架网络模型可以应用于损伤(或裂缝)混凝土的氯离子运移分析。
Abstract A meso-scale truss network model was developed to predict chloride diffusion in concrete. The model regards concrete as a three-phase composite of mortar matrix, come aggregates, and the interfacial transition zone (ITZ) between the mortar matrix and the aggregates. The diffusion coefficient of chloride in the mortar and the ITZ can be analytically determined with only the water-to-cement ratio and volume fraction of fine aggregates. Fick's second law of diffusion was used as the governing equation for chloride diffusion in a homogenous medium (e.g., mortar); it was discretized and applied to the truss network model. The solution procedure of the truss network model based on the diffusion law and the meso-scale composite structure of concrete is outlined. Additionally, the dependence of the diffusion coefficient of chloride in the mortar and the ITZ on exposure duration and temperature is taken into account to illustrate their effect on chloride diffusion coefficient. The numerical results show that the exposure duration and environmental temperature play important roles in the diffusion rate of chloride ions in concrete. It is also concluded that the meso-scale truss network model can be applied to chloride transport analysis of damaged (or cracked) concrete.