Correlation of flaw structure and cracking behavior in SHCC with X-ray CT scanning technique

Abstract

Strain Hardening Cementitious Composites (SHCC) are materials featuring multiple cracking and strain hardening behavior. The variation of SHCC’s tensile performance, especially the tensile strain capacity, has long been a puzzle for civil engineers who seek broader infrastructural application of this advanced material. The tensile performance of SHCC is governed by the random distribution of flaw size and fiber content, but the correlation between them has not been comprehensively studied. The present work reconstructed the flaw structure of a number of SHCC specimens utilizing X-ray CT scanning technique and established the cracking strength distribution for each specimen based on a modified fracture mechanics model. The distribution was correlated with the bridging capacity of the cross-section with the least fibers and an index η indicating the fractions of cross-sections that can undergo cracking was proposed. The index was found to correlate well with the number of cracks in a tensile test and provides a new approach to evaluate SHCC’s potential to achieve saturated multiple cracking. Finally, artificial flaws in different sizes were added to tailor the flaw structure in order to facilitate the multiple cracking of SHCC, and design suggestions based on the above findings were provided.