Experimental Study on Flexural Behavior of High Strength Concrete Beams with Hybrid Fibers

Abstract

High-strength concrete (HSC) exhibits excellent compressive strength but suffers from brittle failure under flexural loading, limiting its ductility and crack resistance. The incorporation of hybrid fibers has emerged as an effective strategy to overcome these limitations by enhancing post-cracking behavior and energy absorption capacity. This study investigates the flexural performance of HSC beams reinforced with different combinations of steel fibers, polypropylene fibers, and basalt fibers. A systematic experimental program was conducted on reinforced concrete beams with varying fiber dosages and hybrid ratios. The parameters studied include first crack load, ultimate load, load–deflection response, crack propagation, ductility index, stiffness degradation, and flexural toughness. Comparative analysis with control specimens highlights the significant role of hybrid fibers in improving structural performance. The results indicate that beams with optimal hybrid fiber content demonstrated enhanced load-carrying capacity, reduced crack widths, and superior ductility compared to mono-fiber or plain HSC beams. Microstructural analysis through Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) confirmed improved fiber–matrix bonding and crack bridging mechanisms. The study concludes that hybrid fiber reinforcement provides a cost-effective and sustainable solution for improving the flexural behavior of high-strength concrete in structural applications.