Improving Stress-Strain Behavior of Waste Aggregate Concrete Using Affordable Glass Fiber Reinforced Polymer (GFRP) Composites

Several studies have highlighted the potential of crushed brick aggregates in non-structural concrete. This is because crushed brick aggregates offer substandard mechanical properties in comparison to natural stone aggregates. Synthetic Fiber Reinforced Polymer (FRP) sheets have been known to overcome this issue. However, enormous costs associated with synthetic FRPs may limit their use in several low-budget applications. This study recognizes this issue and propose a cost-effective solution in the form of low-cost glass fiber (LC-GFRP) sheets. Two types of brick aggregates (i.e., solid-clay and hollow-clay brick aggregates) were used to fabricate concrete by replacing 50% of natural aggregates. Experimental results of 32 non-circular specimens were reported in this study. To overcome the substandard mechanical properties of recycled brick aggregate concrete (RBAC), specimens were strengthened with 2, 4, and 6 layers of LC-GFRP sheets. Noticeable improvements in ultimate compressive stress and corresponding strain were observed and were found to correlate positively with the number of LC-GFRP sheets. It was found that 4 and 6 layers of LC-GFRP sheets imparted significant axial ductility irrespective of the brick aggregate type and inherent concrete strength. Several existing stress-strain models for confined concrete were considered to predict ultimate confined compressive stress and corresponding strain. Accuracy of existing models was assessed by mean of the ratio of analytical to experimental values and associated standard deviations. For ultimate stress predictions, the lowest mean value of the ratio of analytical to experimental ultimate compressive stress was 1.07 with a standard deviation of 0.10. However, none of the considered models was able to provide good estimates of ultimate strains.