Fatigue strength evaluation of steel-fibre-reinforced pavement-quality geopolymer concrete using probabilistic approach

This aim of this study was to minimise the brittleness of geopolymer concrete mixes by adding steel fibre (SF) at different dosages by volume proportion of concrete, conforming to code requirements. A pavement-quality geopolymer concrete (PQGC) was produced after evaluating various trial mixes under ambient curing conditions. This investigation was primarily focused on the fatigue performance of SF-reinforced PQGC (SF-PQGC) under repeated loading at stress ratios of 0.7–0.9. Experimental fatigue life data were used to construct curves of stress ratio against number of cycles to failure, and the fatigue equation coefficients were evaluated for various values of the probability of survival (PoS) using the Weibull distribution method to predict the fatigue strength of PQGC and SF-PQGC with an intended PoS of 0.90. The observed fatigue strength at an endurance limit of PQGC mix was enhanced significantly at around 21% with the incorporation of 0.5% dosage of SFs; this was attributed to the SFs bridging cracks, pull-out and fracture of bridged SFs, which led to delayed failure under repeated loading conditions. By demonstrating the benefits of using SFs in PQGC, the results of this study pave the way for the wider adoption of PQGC in pavement construction.