Assessment of bond durability between GFRP bars and concrete produced with seawater under seawater exposure at different temperatures

The growing interest in the use of Glass Fiber Reinforced Polymer (GFRP) bars to reinforce concrete structures, mainly due to their non-corrosion characteristics, allows for the development of more sustainable solutions in the production of reinforced concrete structures, such as using seawater instead of freshwater directly in the concrete composition. Through direct pullout tests (DPT), this work evaluated the bond durability of GFRP bars to concrete produced with seawater (SW) and freshwater (FW) after being subjected to seawater exposure at different temperatures, namely 20 °C, 40 °C and 60 °C, over two years. Unconditioned (reference) air-cured specimens were also tested for comparison. The mechanical properties of the constituent materials in the study, i.e., concrete and GFRP bars, and their influence on bond strength were also analyzed. Finally, the accuracy of existing formulations to predict the bond strength was assessed. The use of SW instead of FW resulted in a reduction in bond strength of approximately 43 % in unconditioned specimens, whereas only a 13 % reduction was observed in specimens conditioned for two years (SW versus FW). Additionally, exposure conditions did not cause significant changes in the failure modes nor with increasing temperature or time. Furthermore, the ACI provisions accurately predicted the bond strength of the two compositions studied. • Comparison of concrete produced with fresh and sea water. • Bond durability between GFRP bars and seawater concrete. • Mechanical properties of fresh and seawater concrete tend to be similar over time. • Durability performance is not compromised with seawater concrete. • ACI provisions accurately predicted the bond strength of the studied concrete.