Quantification of concrete chloride diffusion coefficient – A critical review
Quantification of concrete chloride diffusion coefficient – A critical review
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DOI：
10.1016/j.cemconcomp.2019.03.011
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发表时间：
2019-05
影响因子：
10.5
通讯作者：
M. Shafikhani;S. Chidiac
中科院分区：
文献类型：
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作者：
M. Shafikhani;S. Chidiac
大多数混凝土劣化机制是由传输特性驱动的，特别是氯化物扩散系数。因此，已经开发了实验和分析工具来量化氯化物扩散系数。本研究采用文献中报道的实验数据来严格评估所提出的用于量化混凝土氯离子扩散系数的分析模型的准确性和精密度。评估的模型范围从统计模型到混合模型，前者采用统计工具来拟合响应函数，后者结合材料科学、物理科学和数学工具来表征特性。测试数据包括两种标准测试方法，即体积扩散和迁移测试，并考虑以下混合物设计变量：水灰比、水泥类型和含量、辅助胶凝材料、骨料体积分数和空气含量。结果表明，与统计模型相比，混合模型更加准确和精确。我们发现“最佳”模型考虑了毛细管孔隙率、孔隙结构参数、固相扩散率、水泥浆扩散率、骨料体积分数和界面过渡区特性，从而产生了 0.86 和 0.97 的量化扩散系数的 ±95% 置信可预测性。所有模型中都缺少控制各种扩散系数比率的水泥浆厚度。
Most concrete deterioration mechanisms are driven by the transport properties, in particular the chloride diffusion coefficient. As such, experimental and analytical tools have been developed to quantify the chloride diffusion coefficient. This study employs the experimental data reported in the literature to critically assess the accuracy and precision of the proposed analytical models for quantifying the concrete chloride diffusion coefficient. The models assessed range in scope from statistical models to hybrid models with the former employing statistical tools to fit the response function and the latter combining material science, physical science and mathematical tools to characterize the property. The test data include two standard test methods, i.e. bulk diffusion and migration test, and consider the following mixture design variables: water to cement ratio, cement type and content, supplementary cementing material, aggregate volume fraction, and air content. The results revealed that hybrid models are more accurate and precise in comparison to the statistical model. The “best” model is found to account for the capillary porosity, pore structure parameters, solid phase diffusivity, cement paste diffusivity, aggregate volume fraction, and interfacial transition zone properties yielding a ±95% confidence predictability of 0.86 and 0.97 of the quantified diffusion coefficients. Cement paste thickness which controls the ratios of the various diffusion coefficients is found missing in all the models.