Bond durability of BFRP bars embedded in concrete under seawater conditions and the long-term bond strength prediction

This paper presents a bond durability test for the basalt fiber-reinforced polymer (BFRP) bar to concrete immersed in seawater. Glass fiber-reinforced polymer (GFRP) bars, carbon fiber-reinforced polymer (CFRP) bars and steel bars are tested for comparison. Test parameters include the fiber type, the resin type, the temperature and the surface treatment. 114 cube specimens are constructed and tested in direct pullout conditions, and 99 of them are immersed in seawater for different durations and at different temperatures. Scanning electron microscope is used for microstructural observation. Moreover, a long-term bond strength prediction is conducted on the BFRP bar to concrete. Test results show that the maximum bond strength of the basalt-vinyl ester (BV) bar and the glass-vinyl ester (GV) bar to concrete experiences degradation, while the value of the basalt-epoxy (BE) bar to concrete remains essentially unchanged. The value of the carbon-epoxy (CE) bar to concrete shows increasing trend. Sand-coating the ribbed BFRP bar reduces the short-term bond strength but improves the long-term bond durability. The prediction results indicate that the bond strength retention of the BV bar in a chloride environment would be above 93%, 78% and 47% after 50 years' service in dry, moist and moisture saturated environment, respectively. (C) 2015 Published by Elsevier Ltd.