Experimental study on the bond performance between BFRP bars and coral concrete

To study of the bond performance between BFRP bars and coral concrete, pull-out tests were carried out for 24 anchorage specimens with FRP bars of different diameters (d=8 mm and d=12 mm), different bonding lengths (2.5 d, 5.0 d and 7.5 d) and different curing conditions (standard curing room and artificial seawater immersion with the temperature of 20±2℃). The results show that all the specimens fail due to the pull-out of the BFRP bars from the concrete except the specimens with 12 mm diameter bars and a bonding length of 7.5 d, which is identified by splitting failure of the concrete. The failure mode is similar to that between BFRP bars and ordinary concrete, but the splitting failure occurs more easily for the bond between BFRP bars and coral concrete. The bond-slip curve can be divided into five stages, i.e., micro slip stage, sliding stage, stripping stage, declining stage and residual stage. With the increase of the diameter and bond length, the maximum average bond stress decreases markedly. Moreover, the bond strength of the specimens under standard curing conditions is apparently larger than that of specimens immersed in 20±2℃ artificial seawater.