Analysis of the Crack Evolution Process in Crumb Rubber Concrete Based on Acoustic Emission Technology

In this study, the crack evolution process of crumb rubber concrete (CRC) in a four-point bending tensile test was monitored using the acoustic emission (AE) technique. The peak frequency, distribution characteristics of the AE source, and the damage process based on the AE ring count during the crack evolution were analyzed. The test results revealed that the addition of rubber particles decreased the brittleness of cracks and improved the ductility of the concrete during the macro-cracking process. The AE positioning method could effectively monitor the evolution process of micro-cracks inside the concrete. Additionally, based on the statistical results of the AE source events and energy distribution, the position of macroscopic cracks could be predicted, and the random distribution of micro-cracks could be characterized. By introducing the Weibull distribution to describe the random growth process of micro-cracks, the damage inside the concrete could be qualitatively predicted. As the rubber particle content increased, the inherent micro-cracks inside the concrete also increased. The damage inside the concrete was biased toward the crack nucleation stage.