Bond durability between GFRP bars and seawater sea sand concrete in marine environments

The combination of fibre reinforced polymer (FRP) bars and seawater sea-sand concrete (SSC) has significant potential for application in marine environments. However, centre pull-out specimens employed in previous research may not align with actual engineering conditions. In this study, traditional pull-out specimens were modified to account for actual concrete cover thickness and avoid direct exposure of bond interfaces. This innovative design was more suitable for durability tests. The influence of marine environments on the bond performance between GFRP bars and SSC was evaluated using 65 pull-out specimens. The research parameters included exposure time, ambient temperature, seawater salinity, and concrete cover thickness. Experimental results showed that previous research might overestimate the bond durability between FRP bars and concrete in marine environments by neglecting the effect of concrete cover thickness. A refined method for predicting longterm bond strength, considering design life, ambient temperature, and relative humidity, was proposed. This method could guide the design of long-term anchorage length. Additionally, the effect of marine environments was further incorporated into mBPE model.