Acoustic emission monitoring of fracture of fiber-reinforced concrete in tension

An attempt was made to experimentally investigate the fracture behavior of fiber-reinforced concrete (FRC) by acoustic emission (AE) characterization during direct uniaxial tensile loading. A previous investigation indicated that conventional concrete incorporating short fibers can produce FRC showing a strain-softening response or a strain-hardening response in tension. These two types ofFRCs were further investigated using AE techniques, and the results are reported in this paper. A recently developed uniaxial direct tensile test technique was used to conduct tensile tests on specimens without notches. AE monitoring was performed during the entire course of each tensile test. Analyses ofAE activities and source locations of AE events were then performed to study the damage initiation and propagation in the materials. Results show that nucleation of microcracks can be clearly observed for the FRC that shows a nonhardening response, similar to concrete without reinforcement. For FRC showing a hardening response, this phenomenon cannot be observed, which indicates that the fibers were effective in blunting the microcrack nucleation. Comment