Microscopic effects on chloride diffusivity of cement pastes - a scale-transition analysis
Microscopic effects on chloride diffusivity of cement pastes - a scale-transition analysis
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DOI：
10.1016/j.cemconres.2004.04.010
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发表时间：
2004-12-01
影响因子：
11.4
通讯作者：
Smith, D
中科院分区：
文献类型：
--
作者：
Pivonka, P;Hellmich, C;Smith, D
为了评估结构的耐久性，非常需要量化和模拟氯离子在混凝土中的扩散过程。为此，扩散池实验提供的氯离子扩散系数的水泥浆体与不同的水灰比（有关不同的微孔）进行了评估的尺度转换分析。对于表观氯离子扩散率的预测，水泥浆体可以建模的差分均匀化计划，涉及非扩散的球形夹杂物在扩散矩阵的装置。结果表明，水泥石的氯离子扩散系数是微孔隙率和氯离子在水泥浆中扩散系数的函数。值得注意的是，后者原来是一个数量级小于纯盐溶液系统中的氯化物扩散系数。扩散系数较小可能是由于水分子沿着水泥浆体孔隙表面结构化所致。(C)2004 Elsevier Ltd.保留所有权利。
For estimation of the durability of structures, it is highly desirable to quantify and simulate the chloride diffusion process in concrete. To this end, diffusion-cell experiments delivering the chloride diffusivity of cement pastes with different water-cement ratios (related to different microporosities) are evaluated in a scale-transition analysis. For prediction of the apparent chloride diffusivity, cement paste can be modelled by means of a differential homogenization scheme involving nondiffusive spherical inclusions in a diffusive matrix. As a result, chloride diffusivity of cement paste is obtained as a function of the microporosity and the chloride diffusivity in the micropore solution. Remarkably, the latter turns out to be one order of magnitude smaller than the chloride diffusivity in a pure salt solution system. The smaller diffusivity is probably caused by structuring of water molecules along the pore surface of cement paste. (C) 2004 Elsevier Ltd. All rights reserved.