Influence of polyester microfiber reinforcement on flexural fatigue characteristics of concrete

The concrete with polyester microfiber is being investigated for the behaviour of flexural strength under static loading. But their behaviour under dynamic loading is unclear and hence there is a need for a comprehensive study. The fatigue performance of concrete with polyester microfiber (0.0, 0.9, 2.0, and 3.0 kg/m3 by volume of concrete) under flexural loading is studied. The cyclic loads are applied at constant maximum stress levels of 80, 85, and 90%, whereas the minimum stress level is fixed at 2% of the static flexural strength of the concrete. The stress level vs. fatigue life (S-N) curves are formulated to observe the effectiveness of microfiber on fatigue performance, follow the logarithmic relationship. Under all the stress levels, concrete with fibre dosage of 0.9 kg/m3 is shown pronouncing effect on fatigue lives compared to concrete with other fibre dosages. The fatigue results are in better agreement with two-parameter Weibull and lognormal distributions. The analysis of covariance (ANCOVA) indicated that the initial stiffness and stress levels are significant in affecting fatigue lives. The unified model is proposed for damage evolution, which can be satisfactorily used to describe the damage of concrete.