Fatigue behavior of basalt fiber-reinforced polymer tendons under a marine environment

• Hydrolyzation dominates fatigue strength degradation of BFRP in marine environment.
• Higher aging temperature leads to larger fatigue strength decrease of BFRP tendon.
• The impact of salt corrosion to the fatigue behavior is limited below 0.08 fu.

Due to their advantageous mechanical behaviors and anti-salt properties, basalt fiber-reinforced polymer (BFRP) tendons are a promising prestressing component under a marine environment. However, the degradation law of fatigue behavior of BFRP tendons under a marine environment is still unclear. This paper studies the fatigue behavior of BFRP tendons after aging in a salt solution by temperature-accelerated experiments. The degradation mechanism of fatigue behavior is clarified based on previous studies and analysis of the failure mode. The effect of aging temperature on fatigue strength degradation is analyzed using both experimental data and scanning electron microscopy (SEM) images. Moreover, the fatigue strength degradation of BFRP tendons at different local temperatures was predicted according to the Arrhenius equation. The results show that the fatigue strength degradation of BFRP tendons is governed by the weakened fiber-matrix interface resulting from the hydrolyzation of Si–O–Si chemical bonds in salt solution. SEM showed that specimens aged at 55 °C for 63 days demonstrate increased corrosion than those in other groups. Through the Arrhenius equation, the fatigue strengths of BFRP tendons are predicted to be 0.41, 0.43 and 0.45 fu, respectively, at three representative northern latitudes after 100 years of aging in marine environments. The results provide guidance for fatigue design of BFRP tendons in a marine environment.