Engineered Cementitious Composites (ECC) are high-performance cementitious materials that exhibit multiple cracking and self-controlled width under uniaxial loading, which can lead to a low permeability. Quantifying the water flow behavior of an ECC crack is a precondition for its practical application. However, the lack of characterization for internal crack profiles and advanced modeling for water flow behavior leads to unsatisfactory permeation predictions. Focusing on these two shortages, this study characterized and reconstructed the inner 3D crack profiles based on X-CT technology and, in combination with lattice Boltzmann method (LBM), simulated the water flow behavior in an ECC crack. According to permeation test on an ECC crack, a width reduction factor of 0.67 should be adopted for permeation prediction of this particular ECC sample in the present experiments. By considering rough surfaces, numerous bridging fibers and fragmented matrix blocks in the simulation, good agreement between simulation and test results was achieved. Based on the proposed modeling approach, the impact of crack width on permeability was then discussed. Moreover, a quantitative investigation on the effect of these three geometric elements revealed that rough surfaces, fiber diameter and volume fraction are critical factors that cannot be ignored when determining the width reduction factor.

中文翻译：

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基于格子玻尔兹曼法和 X 射线计算机断层扫描研究裂纹 ECC 的透水行为

工程水泥基复合材料 （ECC） 是高性能水泥基材料，在单轴载荷下表现出多次开裂和自控宽度，这可能导致低渗透性。量化 ECC 裂纹的水流行为是其实际应用的先决条件。然而，缺乏对内部裂缝剖面的表征和对水流行为的高级建模，导致渗透预测不令人满意。针对这两个不足，本研究基于 X-CT 技术对内部 3D 裂纹剖面进行了表征和重建，并结合晶格玻尔兹曼法 （LBM） 模拟了 ECC 裂纹中的水流行为。根据对 ECC 裂纹的渗透测试，本实验中该特定 ECC 样品的渗透预测应采用 0.67 的宽度缩减因子。通过在模拟中考虑粗糙的表面、大量的桥接纤维和碎片化的基体块，实现了模拟和测试结果之间的良好一致性。基于所提出的建模方法，讨论了裂缝宽度对渗透率的影响。此外，对这三个几何元素影响的定量调查表明，粗糙表面、纤维直径和体积分数是确定宽度缩减因子时不能忽视的关键因素。