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

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 eta 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.

Automated summary

This study utilized X-ray CT scanning technique to reconstruct the flaw structure of SHCC materials and explained its tensile performance through establishing cracking strength distribution. The study found that the potential of saturated multiple cracking in SHCC materials can be evaluated using an index called eta, which provides a new approach for further design optimization.