Structural Efficacy and Economic Viability of RC Beams Retrofitted with Hybrid Glass-Jute FRP Composites: An Experimental Study

The progressive deterioration of reinforced concrete (RC) structures due to aging, overloading, and environmental exposure necessitates efficient retrofitting strategies. While conventional synthetic Fiber Reinforced Polymer (FRP) systems provide high strength, they are often limited by high material costs and environmental impact. This study investigates the flexural response of RC beams strengthened with a sustainable Glass-Jute Hybrid Fiber Reinforced Polymer (HFRP) composite, aimed at balancing structural performance, cost-efficiency, and environmental sustainability. The experimental program involved twelve (12) RC beams (100 mm x 150 mm x 1200 mm) cast using M25 grade concrete and Fe550 steel. A hybrid laminate with a [Glass/Jute/Glass] stacking sequence was developed, yielding a tensile strength of 510 MPa. Three wrapping configurations—Bottom Wrap (Type B), Side Wrap (Type C), and U-Wrap (Type D)—were tested under four-point bending and compared against unstrengthened control specimens. The results demonstrate a substantial improvement in structural capacity across all retrofitted specimens. The U-Wrap configuration (Type D) exhibited the highest performance, increasing the moment of resistance by 62.8% and significantly improving crack control. The Side (Type C) and Bottom (Type B) configurations provided increases of 52.7% and 30.1%, respectively. Beyond strength gains, the HFRP shifted the failure mode from brittle shear failure in control beams to a more ductile flexural-compression failure. A comprehensive cost-benefit analysis revealed that while the U-Wrap offered maximum strength, the Bottom Wrap was the most economically efficient, providing a 12.0% strength gain per ₹100 spent. These findings provide evidence that Glass-Jute HFRP laminates serve as a technically viable, cost-effective, and sustainable alternative for structural retrofitting, offering a foundation for the development of hybrid composite design guidelines.