Effects of sea water soaking on the bonding properties of FRP bars-coral concrete

The experimental study on the bond properties of glass fiber reinforced polymer (GFRP) bars and coral concrete, carbon fiber reinforced plomer (CFRP) bars and coral concrete under sea water immersion at 30℃ was carried out. The characteristics of bond slip curves, failure modes and bond strength of fiber reinforced polymer(FRP) bars-coral concrete were analyzed. The results show that the mechanical properties and adhesive properties of FRP bars decrease in different degrees after immersion in seawater. With the increase of soaking time, the porosity between surface resin and fiber increases evidently, the phenomenon of debonding occurrs gradually, and the fiber itself is that of GFRP bars. The ultimate bond strength of FRP bars-coral concrete shows a trend to increase at first and then decreases and the later falling rate gradually becomes smaller. The failure modes of some GFRP bars-coral concrete specimens gradually change into bar fracture from pull-out. Increasing the cover thickness of coral concrete could reduce the erosion of the sea water to the FRP bars effectively, and helps to maintain the bond performance of the GFRP bars-coral concrete.