EFFECT OF INTERFACIAL BOND ON PERFORMANCE OF NATURAL FLAX FRP CONFINED COIR FIBRE REINFORCED CONCRETE

Extensive studies showed that the effect of glass/carbon FRP and concrete interfacial bond has an effect on the structural performance of FRP confined concrete structure since the load transfer from FRP to concrete is via the interface. This study experimentally investigated the effect of interfacial bond between flax FRP(FFRP) tubeand coir fibre reinforced concrete (CFRC) on the axial compressive and flexural behavior of FFRP tube encased CFRC (FFRP-CFRC) composite structure. The types of FFRP/CFRC interfacial conditions considered were that the CFRC was confined by (i) normal FFRP tube and (ii) FFRP tube with FFRP/CFRC interlocking, which were termed as normally and interlocked bonded conditions between FFRP and CFRC, respectively. Experimental results show that in both types of bond conditions, the confinement provided by the outer FFRP tube lead to a remarkable increase in ultimate compressive strength, ultimate axial strain and energy absorption capabilities of the concrete. However, the ultimate compressive strength and strain of normal bonded specimen is larger than those in interlocked specimen. The use of interlocking did not reduce the lateral load carrying capability compared with the normal bonded specimen but eliminated the slippage between FFRP and CFRC effectively.