Meso-level pore structures of Strain-Hardening Cementitious Composites (SHCC): Correlation with matrix flowability and application in micromechanical modeling

The meso-level pore structure of Strain-Hardening/Engineered Cementitious Composites (SHCC/ECC) critically governs cracking strength distribution, and consequently the tensile performance. While pore distributions are typically attributed to matrix flowability, this relationship remains rarely quantified for SHCC. This study addresses this gap by linking material processing parameters, realistic pore structures, and tensile cracking behaviors of SHCC. Using X-ray computed tomography (X-CT), the 3D meso-level pore information (including porosity, size distribution, shape factors, and spatial distribution) of SHCC specimens was analyzed and correlated with matrix flowabilities. Mechanisms governing pore formation during mixing and casting were discussed. A statistically derived correlation between meso-level pore structures and matrix flowability was established and applied to predict cracking strength distributions. This correlation demonstrated improved agreement with experimental results over conventional methods. These findings advance the modeling and optimization of SHCC by providing a quantitative framework to account for matrix flowability effects. • Meso-level pore structures were correlated with matrix flowability in SHCC/ECC. • Maximum porosity occurs at medium flowability, counter to previous viscosity assumptions. • Pore shape and size are interdependent; flowable matrices produce rounder pores than viscous ones. • A statistical correlation between meso-level pore structures and matrix flowability was established. • Our predicted cracking strength distribution has improved agreement with experimental results.