Compression behavior of concrete cylinders externally confined by flax fiber reinforced polymer sheets

In this article, a bi-directional flax fiber fabric with room temperature curable epoxy was used to confine concrete cylinders. The compression performances of the confined cylinders were tested on the compressive behaviors. For comparison, unidirectional basalt fiber fabric reinforced polymer (BFRP) confined cylinders were also tested. Compared to the BFRP wet layups, the flax fiber reinforced polymer (FFRP) composite exhibits nonlinear in tension, and relatively lower tensile strength and modulus, but higher elongation. FFRP in weft direction exhibits higher strength and modulus but lower elongation than that that in warp direction. The compressive test results of confined concrete cylinders indicate that FFRPs improved the ultimate strain and stress of the confined cylinders, remarkably. The coefficients of confinement of FFRP on the ultimate compression stress are slightly higher than that of BFRP. The confined cylinders with FFRP showed much higher ultimate axial strain than those with BFRP.