Axial behavior of concrete confined with flax fiber-reinforced polymers

Objective: This research was carried out to investigate the axial behaviour of low-strength concrete which is confined with unidirectional flax fiber reinforced polymer (FFRP) alone or in the hybrid form with glass FRP (GFRP) and carbon FRP (CFRP). Material and Methods: In this research, the type of confinement (using single material or hybrid) and number of confining layers constitute the main testing parameters. The FRP materials were wrapped around the concrete cylinder specimens with epoxy resin using the hand lay-up method and thus confinement is provided. The confined concrete specimens were tested under monotonic axial compression. Results: A total number of 23 concrete cylindrical specimens were tested within this study. The results demonstrate that strength and ultimate strain capacity of the concrete specimen increase significantly even for the specimens confined only with the FFRP. In the hybrid form, a higher enhancement in the axial behavior could be achieved.