Water absorption and long-term thermal and mechanical properties of carbon/glass hybrid rod for bridge cable

Fiber reinforced polymer (FRP) composites rod has been used as cable in long-span bridge structure owing to the light weight, high strength and corrosion resistance. The hygrothermal aging will degrade the service performances of FRP cable significantly. In the present study, the accelerated aging experiment of carbon/glass fiber reinforced hybrid rod is conducted through the immersion in deionized water at 40 °C, 60 °C and 80 °C for 403 days. The water absorption and diffusion behavior, evolution of fiber-matrix interfacial strength and dynamic thermo-mechanical property are investigated experimentally. Furthermore, the microstructure characterization is conducted to reveal the degradation mechanism. The results show that the water absorption and diffusion behavior of hybrid rod conforms to a two-stage model, the resin relaxation and interfacial debonding bring about more diffusion path for water molecules at second stage. The resin plasticization and interfacial debonding are the prominte factors lead to the degradation of interfacial strength and glass transition temperature. Furthermore, it is found that the plasticization effect is reversible with the removal of bonding water after drying, while the interfacial debonding is permanent. The long-term life evaluation shows that interface shear strength of hybrid rod shell has a fast degradation rate and reaches to a stable level of 62 %, which provides the key design parameter for bridge structures.