Compressive behaviour of flax FRP double tube confined coconut fibre reinforced concrete

The use of natural fibre reinforcement in polymer and concrete composites has in recent years attracted significant research interest. When coconut fibre reinforced concrete (CFRC) is confined by flax fibre reinforced polymer (FFRP), the strength of FFRP-CFRC composite is significantly enhanced. While researchers have studied the effect of FFRP confinement on compressive strength, their work has mainly focussed on the outside confinement of CFRC. In contrast, this study considers a double confinement, i.e. CFRC is confined respectively by large and small FFRP tubes both externally and internally. The experimental results show that in comparison with single confinement, double confinement enhances the axial compressive strength and strain of the FFRP-CFRC composite, even though less concrete is used.