Abstract: Experiments were carried out to study the basic mechanical property of seawater coral concrete and the bond performance between coral concrete and BFRP bars under different marine curing environment (tidal zone immersion and seawater immersion), different bonding lengths (2.5d, 5.0d and 7.5d), different diameters (d=8 mm and d=12 mm), and different curing periods (30 d, 60 d and 90 d). The test results show that the compressive strength, axial compressive strength, flexural strength and elastic modulus of coral concrete show a trend of increase first and then decrease with the increase of the curing age, the specimens with a bond length of 2.5d and 5d fail due to the pull-out of the BFRP bars from the concrete, while the specimens with a bond length of 7.5d fail due to the split of the coral concrete or the BFRP bar. The bond-slip curve can be divided into five stages, which include micro slip stage, sliding stage, stripping stage, declining stage and residual stage. Under the same condition, the maximum average bond stress decreases with the increase of the bond length and the diameter, while the residual bond stress decreases with the increase of bond length, the maximum average bond stress in seawater zone is higher than that in tidal zone. With the growth of the curing age, the maximum average bond stress value of the specimens for diameter of 8 mm show an upward trend, and that of the specimens for diameter of 12 mm show a trend of increasing first and then decreasing. The residual bond stress in the seawater immersion environment shows a trend of increasing first and then decreasing, and it shows a trend of decreasing gradually in the seawater tidal environment.

Key words: BFRP bar, coral concrete, marine environment, bond performance, failure mode, diameter, curing period, curing environment, composites