Behavior of flax frp tube confined coir fibre reinforced concrete column: Bond effect

This study investigated the effect of flax fibre reinforced polymer (FFRP) and concrete bond on the compressive behaviour of FFRP tube confined coir fibre reinforced concrete (CFRC). Two types of bond were considered, i.e. concrete confined by (i) FFRP tube and (ii) FFRP tube with internal holes. They were termed as naturally and mechanically bonded specimens, respectively. The test results indicated that the two FFRP confinements increased the ultimate strength and ductility of the concrete significantly compared to the unconfined concrete. It was found that the type of FFRP and concrete bond had a significant effect on the ultimate strength and axial strain of the confined cylinders. The naturally bonded composite cylinder offered a larger ultimate compressive strength compared with the mechanically bonded cylinder. In the cases of FFRP confined CFRC, the coir fibre inclusion reduced the numbers and widths of the cracks in the concrete compared with the FFRP tube confined plain concrete.