Studying water permeation behavior of cracked ECC based on lattice Boltzmann method and X-ray computed tomography

Abstract

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.