Evaluation of crack opening performance of a repair material with strain hardening behavior

One of the novel mechanical properties of strain hardening cementitious composites (SHCC) is that they exhibit multiple fine cracks and strain hardening in tension. This promotes the use of SHCC as an effective repair material, because penetration of substances through the fine cracks is greatly reduced. Most research on SHCC has focused on its behavior and results obtained from uniaxial tensile tests. However, the crack distribution of the repair material (SHCC) layer is more concentrated adjacent to an existing crack in a substrate. So the design procedure considering the crack opening, which represents the potential for localized fracture, should be established for appropriate material selection. In this paper, the performance of SHCC as a repair material was assessed through three tests: uniaxial tensile tests; zero-span tensile tests; and flexural tests of RC beams repaired with SHCC. Comparisons between crack opening performances and the observed crack patterns of the three tests were conducted. The crack opening and crack pattern obtained from the zero-span tensile tests were similar to those of the repaired beam specimens. According to the zero-span tensile tests, the performance of cracking behavior of the repair material on an existing crack can be estimated. On the other hand, the deformation capacity of SHCC obtained from the uniaxial tensile tests cannot be directly applied to the design of surface repair application.