Experimental study on the effects of glass fibres and expansive agent on the bond behaviour of glass/basalt FRP bars in seawater sea-sand concrete

Abstract

In seawater sea-sand concrete (SSSC), to avoid steel corrosion, the use of fibre-reinforced polymer (FRP) bars as reinforcement has been proposed. However, FRP bars do not have strong ribs for bonding, and thus, may have weaker bonds compared to steel reinforcing bars. To overcome this problem, the addition of fibres and expansive agent to concrete to induce gripping stresses on FRP bars may be a feasible solution. In this research, the effects of glass fibres and expansive agent on the bond behaviour of glass/basalt FRP bars cast in SSSC were studied by conducting pull-out tests with varying fibre content, fibre length, and expansive agent content. The results revealed that although the addition of glass fibres and/or the expansive agent significantly increases the bond stiffness, it only marginally increases the bond strength of the FRP bars. Overall, the addition of both fibres and the expansive agent offers certain synergistic effects; however, improving the bond strength is still difficult owing to the premature failure of the FRP bars. Finally, constitutive models to simulate the bond behaviour of FRP bars in SSSC were proposed.