Assessment of fracture process of engineered cementitious composite (ECC) by time-frequency analysis of acoustic emission signals

Engineered cementitious composite (ECC), also known as strain-hardening cementitious composite, exhibits high ductility and high toughness. The high ductility and high toughness of ECC are associated with finely-tuned matrix cracking, fiber rupture, and fiber-matrix debonding. This study investigates the fracture process of ECC through a time-frequency analysis of acoustic emission (AE) signals. The frequency characteristics of individual AE hits were used to evaluate different types of damage throughout the fracture process. The evolution of damage was assessed, and the AE energy was calculated. The effects of matrix flaw and fiber content on the fracture process were investigated. The test results revealed that different damage stages featured different AE frequency characteristics, which were used to classify damage types. ECC showed high energy absorption along with the high toughness. This research enhances the understanding of the fracture process of ECC and advances the capability of assessing the damages.