Experimental study and numerical simulation on bond between FFRP and CFRC components

Natural flax fabric-reinforced polymer (FFRP) tube encased coir fibre-reinforced concrete (CFRC) structure (termed as FFRP-CFRC) is steel-free hybrid structure that has shown its potential as axial, flexural and earthquake-resistant structural members. An FFRP plate with a CFRC overlay has great potential to be light and environmentally friendly wall panelor pedestrian bridge deck. The overall structural performance of this panel or deck is highly dependent on the bond at the FFRP and CFRC interface. Therefore, this study proposed a novel interlocking at their interface to improve the bond and thus the composite action of the hybrid structures composed of FFRP and CFRC components. This interlocking was generated by creating numbers of perforations on the FFRP component (tube and plate) surface. To evaluate the effectiveness of using this interlocking on the bond behaviour between FFRP and CFRC, two stages experimental studies were conducted. In the first stage, 18 FFRP-CFRC cylindrical specimens were constructed and tested under push-out bond, bending and axial compression. In the second stage, 30 FFRP plate and CFRC sandwich block specimens were constructed and tested under push-out bond considering different experimental parameters, i.e. depth, diameter and number of perforations. Additionally, numerical simulation was performed to verify the failure modes of FFRP plate and CFRC sandwich blocks under push-out. This study revealed that the presence of interlocking is an effective way to improve the interfacial bond and composite action between FFRP (either tube or plate) and CFRC components.