Synergistic effect of acidic environmental exposure and fatigue loads on FRP tendons

Abstract The synergistic effect of acidic environmental exposure and fatigue loads on fiber-reinforced polymer (FRP) tendons was investigated in this study. The fatigue behavior of basalt FRP tendons under cyclic loads and exposed to air, water, and acid was evaluated. Three types of fatigue tests, that is, air, water spraying, and acid spraying tests, were performed at 40 °C. Another set of preconditioned specimens was prepared by immersing in an acid solution without stress for a designated period. Fatigue stresses of 25%fu–65%fu (where fu is the tensile strength) were applied at a stress ratio of 0.5. The failure mechanism was analyzed at macroscopic and microscopic scales. The results showed that water spraying had the most negligible impact on fatigue behavior, and the acid spraying specimens exhibited 58% faster degradation than the water spraying specimens. Moreover, the synergistic effect of the acid and cyclic stress facilitated the failure process of the acid spraying specimens by 43% compared to the preconditioned specimens. The internal pressure generated by the ingress liquid accelerated resin cracking and fiber–matrix interface debonding. Furthermore, the synergistic effect of the acid and fatigue loads accelerated degradation, owing to the combined effect of internal pressure and chemical corrosion.