Flexural Fatigue Performance of Pavement-Grade Low-Carbon Concrete Containing Waste Clay Bricks

This study investigated the flexural fatigue performance of pavement-grade geopolymer concrete (GPC) developed using low-carbon binders containing waste clay bricks (WCB), slag, and fly ash. Concrete was developed using two types of binders, one with a ternary blend of WCB, slag, and fly ash and one with only slag and fly ash as a full replacement for ordinary portland cement (OPC). Test specimens were subjected to flexural fatigue by four-point bending under three levels of stress which are equivalent to 75%, 80%, and 85% of the maximum static flexural strength. A two-parameter Weibull distribution was considered in the probabilistic analysis of fatigue life data, which corresponds to the number of cycles until failure. At all stress levels, GPC showed better fatigue performance compared to OPC concrete. At lower stress levels, the performance of GPC with WCB in the binder was better than the performance of conventional GPC with only slag and fly ash. However, GPC with WCB shows reduced performance at higher stress ratios. Survival probability of all concrete types (i.e., GPC and OPC concrete) decreased with increasing stress level. At a selected stress level, the fatigue life of all concrete types increased with the decrease of survival probability. The ultimate fatigue strength of GPC was higher than the OPC concrete. GPC with WCB binders showed an ultimate fatigue strength of more than 68% considering 107 repeated loading cycles.