Dynamic Splitting Tensile Damage Characteristics of Steel Fiber–Reinforced Fly Ash Concrete Based on Acoustic Emission Technology

This paper investigates the effects of steel fiber dosage, fly ash replacement rate, and loading rate on the dynamic splitting tensile mechanical properties and acoustic emission (AE) time-frequency characteristics of steel fiber–reinforced fly ash concrete (SFRFAC) in a dynamic splitting tensile loading system combined with AE technology. The Brazilian disc splitting test was performed and AE signals during loading were analyzed by AE time-frequency analysis to study the dynamic splitting tensile mechanical properties and damage characteristics of the SFRFAC. The results show that steel fiber improved the splitting tensile strength losses caused by fly ash, and the synergistic effect of steel fiber and fly ash significantly improved the splitting tensile strength of SFRFAC. The preferable steel fiber dosage was 1% and the preferable fly ash replacement rate was 10%. The peak displacement of SFRFAC increased with the increase of steel fiber, while it decreased with the increase of fly ash and loading rate. The results showed that the steel fiber and fly ash advanced the main time and increased the proportion of the main frequency in the 0–50 kHz frequency band. In contrast, the loading rate has no significant effect on the main time and main frequency of the AE signal of SFRFAC.