Influence of the Steel Fiber Content on the Flexural Fatigue Behavior of Recycled Aggregate Concrete

Steel fiber recycled aggregate concrete (SFRAC) is mainly used in roads, bridges, and railways that are subjected to bear wheel load. This paper presents a comparative experimental study on the flexural fatigue behavior of the SFRAC, the natural aggregate concrete (NAC), and the recycled aggregate concrete (RAC). The results show that, with the use of 1.0% volume fraction steel fiber, the flexural strength of SFRAC exceeds the flexural strength of NAC (around 0.3%), and the fatigue lives of RAC have been found to be lower by 19.9% and 53.4% compared to SFRAC at stress levels S = 0.9 and S = 0.7. The fatigue strain of SFRAC follows the three-stage law, and the fatigue strain of SFRAC develops more slowly than that of RAC at the same stress level. Two-parameter Weibull distribution is fitted to the test data to generate fatigue models at different survival probabilities, and fatigue life can be accurately predicted using the developed model. Therefore, it is feasible to replace the natural concrete with the recycled aggregate concrete with appropriate steel fiber content in some aspects, which is of great significance to green development.