Degradation of GFRP Bars in Reinforced Concrete Exposed to Marine Environments

This project studies the degradation of glass fibre-reinforced polymer (GFRP) bars for reinforced concrete structures after exposure to marine environments. Both resin and GFRP samples were evaluated to shed light on the performance of the individual constituents-fibre and matrix-as well as the FRP system, considering the interactions at the fiber-matrix interfaces. Accelerated ageing conditions were adopted with an elevated temperature at 50 °C and direct immersion in a saline solution comprising sodium chloride (NaCl) and sodium sulfate (Na2SO4). Resin samples were studied in tension (ASTM D638) and short beam shear testing according to ASTM D2344. GFRP bars were evaluated in transverse and interlaminar shear in accordance with ASTM D7617 and D4475 respectively. Both resin and GFRP samples were tested after 15 and 30 days of exposure. Moisture uptake readings of resin samples were regularly taken to correlate diffusivity with mechanical degradation. The study showed a steeper degradation rate in the tensile strength of resin samples and the interlaminar shear strength (ILSS) of the FRP bars at initial exposure times, reflecting the rate of moisture uptake. The transverse shear strength (TSS) in GFRP bars and the resin shear strength degradation varied linearly with exposure time. The findings suggest a correlation between the degradation of resin and matrix dominated properties in GFRP bars. These findings provide valuable insights into the establishment of a test protocol for the durability performance of FRP bars in marine environments.