Natural flax frp tube encased coir fibre reinforced concrete column: experimental

This study investigated the compressive and flexural behavior of FFRP tube confined plain concrete (PC) and coir fibre reinforced concrete (CFRC) composite columns. The mass content of coir fibre considered was 1% of cement. Eighteen cylinders were tested under uniaxial compression and 12 beams were tested under four-point bending. In axial compression, two types of FFRP and concrete bond were considered, i.e. concrete confined by (i) FFRP tube and (2) by FFRP wrappings. They were termed as naturally and mechanically bonded, respectively. Effect of coir fibre inclusion and FFRP confinement on the stress-strain relationship, confinement effectiveness, and load bearing capacity, deflection, and failure mode were studied. Test results show that in compression, both FFRP tube and FFRP wrapping confinements enhance the axial compressive strength and ultimate strain of concrete significantly. In flexure, the FFRP tube can increase the lateral load carrying capacity and the deflection several times larger than the unconfined concrete columns. The flexural behavior of FFRP tube confined CFRC is highly dependent on the tube thickness. Additionally, coir fiber inclusion reduced the numbers and widths of the cracks in the concrete, thus significantly affect the failure mode of FFRP tube confined CFRC in flexure.