An experimental study on fracture characteristics of high-performance fiber-reinforced cement composites through combined acoustic emission and digital image correlation

High-performance fiber-reinforced cement composites (HPFRCC) are regarded as advanced building materials due to high strength and toughness, and favored for the construction, repair, and reinforcement of critical structures. In this study, notched HPFRCC beams with steel fiber volume fractions of 0%, 1%, and 2% were subjected to three-point bending tests. The fracture characteristics and post-cracking behavior were analyzed through the application of digital image correlation (DIC) and acoustic emission (AE) methods. The experimental results demonstrate that fracture energy increases with fiber volume fraction, while the enhancement of fracture toughness through higher fiber content seems to be limited. The effective crack propagation of pure matrix undergoes two stages: rapid development at 5.9 mm/s and slow development at 0.9 mm/s, whereas the corresponding speeds for these two stages of fiber-reinforced matrix are reduced to 3.9 mm/s and 0.3 mm/s. In addition, significant differences in the AE responses in pure and fiber-reinforced matrix were observed, including AE energy, b-value, and damage localization. 1. Fracture performance and post-cracking behavior of HPFRCC was investigated. 2. Three-point bending tests were monitored by combined DIC and AE techniques. 3. Fracture energy increases with fiber content, but toughness plateaus near 1% fiber volume fraction. 4. Effective crack length shows rapid and slow development stages. 5. Steel fibers effectively expand damage zone and reduce crack velocity.