Flexural behaviour of flax FRP double tube confined coconut fibre reinforced concrete beams with interlocking interface

This paper focuses on the flexural performance of flax fibre reinforced polymer (FFRP) tubes confined coconut fibre reinforced concrete (CFRC) composites. In total, six 520 mm long cylindrical specimens with a mechanical bond between CFRC and FFRP tube were constructed. Two configurations were considered: 1). CFRC core confined by a single outer FFRP tube; 2). CFRC filled double FFRP tubes, and the inner tube was placed along the centre line of the cylinder beam. In the third point bending test, the maximum load, flexural deformation and outer tube strains in the longitudinal and hoop directions were measured. It was found that the double tube specimens possessed excellent flexural characteristics, in comparison to the single tube specimens.