Investigation of Ultrahigh-Performance Concrete Fracture Characteristics with Different Steel Fiber Fractions Based on Acoustic Emission
Qing Wang, Xiaoxiao Bao, Jian Yang, Gang Xu, Meng Zhang
Abstract
Three-point bending test and acoustic emission (AE) monitoring of notched beams with different volume fractions of steel fiber ultrahigh-performance concrete (UHPC) were carried out. The results show that the initiation toughness, unstable toughness, and fracture energy of UHPC notched beams increase at first and then decrease with the increase of fiber fraction. Based on the stress intensity factor theory, the simplified formulas for calculating initiation toughness and fracture energy were derived. The acoustic emission signal of the UHPC notched beam fracture process was analyzed, and the characteristics of the UHPC material fracture process were characterized by AE energy and cumulative count. Based on the excellent correlation between AE signal and fracture characteristics, it was found that there is an excellent linear relationship between AE energy and fracture energy, and the relationship between cumulative count and crack mouth opening displacement was established.