Properties and mechanism on flexural fatigue of polypropylene fiber reinforced concrete containing slag

Properties and mechanism were investigated on flexural fatigue of concrete containing polypropylene fibers and ground granulated blast furnace slag(GGBFS). Four polypropylene fibers’ volume fractions and five slag proportions were considered. An experiment was conducted to obtain the fatigue lives at three stress levels in 20 Hz frequency and at a constant stress level of 0.59 in four frequency respectively. Mechanism and evaluation were investigated based on the experimental data. Fatigue life span models were established. The results show that the addition of polypropylene fibers improves the flexural fatigue cumulative strength and fatigue life span. It is proposed that the slag particles and hydrated products improve Interfacial Transition Zone (ITZ) structure and benefit flexural fatigue performance. A composite reinforce effect is found with the incorporation of slag and polypropylene fibers. The optimum mixture contents 55% slag with 0.6% polypropylene fiber for the cumulative fatigue stress. Fatigue properties are decreased as the stress level increasing, the higher frequency reduces the fatigue strength more than lower frequency at a constant stress level.