Hybrid Rebars with Polymer Fibers

Abstract Corrosion of steel reinforcement in concrete structures drives global infrastructure deterioration, necessitating durable alternatives such as fiber-reinforced polymer (FRP) rebars, which provide superior tensile strength-to-weight ratios and chemical resistance. While glass FRP (GFRP) rebars offer cost-effective corrosion immunity, their moderate stiffness and inherent brittleness are perceived as limitations to their widespread adoption; carbon FRP (CFRP) rebars deliver exceptional performance but at a prohibitive unit cost. Hybrid rebars incorporating polymer fibers (HRIPFs) are known for their potential to address these limitations through synergistic fiber architectures balancing cost, reduced density, ductility, and circularity. This study investigates load-differentiated mechanical responses of carbon/glass FRP rebars hybridized with ultrahigh-molecular-weight polyethylene or high-tenacity (HT) polyethylene terephthalate (PET) fibers, identifying performance signatures and optimization pathways. All hybrid formulations achieved density gains of approximately 20%–35% relative to conventional GFRP rebars, confirming the primary advantage of polymer-fiber hybridization in reducing self-weight. Five industrial-scale pultruded HRIPF prototypes were subjected to quasi-static tensile, flexural, and shear testing, as well as accelerated stepped isostress method creep testing. CPE (carbon/polyethylene fiber hybrid) and GPE (glass/polyethylene fiber hybrid) rebars exhibited more than 200% higher shear strain energy density than GFRP references, reflecting enhanced postpeak deformability in shear. Beyond this finding, CPE showed mechanical performance close to or compatible with CFRP rebar design provisions, while glass–PET demonstrated the feasibility of integrating recyclable or recycled thermoplastic fiber, albeit at the cost of reduced elastic properties. Other loading modes showed more modest gains. Scanning electron microscopy correlated these differences with microstructural morphologies, revealing enhanced fiber packing and interfacial characteristics responsible for the superior shear response of CPE and GPE.