Effect of seawater on bond performance between BFRP bars and seawater sea-sand concrete

Abstract

This paper investigates the bond behaviors of BFRP bars with seawater sea-sand concrete (SSC) under seawater conditions. Eighteen experimental cases were established by considering BFRP bar's surface, seawater temperature, and the duration of specimen exposure in seawater as study factors. The BPE and CMR analytical models were calibrated utilizing the test results. Additionally, the bond strength was predicted utilizing the guidelines proposed in FIB Bulletin (40), and the anchorage lengths of deep-ribbed and sand-coated BFRP bars were calibrated. The findings illustrated that all specimens experienced interlaminar shear failure of the bars after immersion in seawater. Although deep-ribbed BFRP bars exhibited the highest initial bond strength, they exhibited greater degradation in the seawater immersion environment. Following 120 days in a 40 °C seawater solution, the bond strength of deep-ribbed BFRP bars was 5.4%, 20.6% lower than that of shallow-ribbed and sand-coated BFRP bars, respectively. The correlation coefficients between the BPE and CMR models and the experimental data were mostly above 0.95. Predicted 50-year results showed that sand-coated BFRP bars would retain between 62.6% and 88.7% bond strength in various conditions. In moisture-saturated environments at different temperatures, it is recommended that the anchorage length for deep-ribbed BFRP bars should range from 32 to 51 times the bar diameter. For sand-coated BFRP bars, the recommended anchorage length is 20 times the bar diameter.