Hybrid basalt/flax fibers reinforced polymer composites and their use in confinement of concrete cylinders

Flax fiber-reinforced polymer composites were determined to be effective in confinement of concrete cylinders. Flax fibers exhibit strong intrinsic hydrophilic properties and relatively inferior mechanical properties; therefore, combining them with mineral-based natural fiber (i.e. basalt fibers) was proposed. In the present study, unidirectional flax-basalt hybrid fiber reinforced polymer plates and tubes were prepared using a filament-winding process. The mechanical properties of the fiber-reinforced polymer plates and compressive properties of the concrete-filled fiber-reinforced polymer tubes were studied. Compared to those of flax fiber-reinforced polymer, hybrid fiber-reinforced polymers exhibited linear rather than bilinear stress-strain curves and enhanced tensile properties. The lateral-axial relationship of the hybrid fiber reinforced polymer-confined concrete cylinders can be well predicted by the classic model for glass- or carbon-based fiber-reinforced polymer-confined concrete cylinders, however, the axial stress-strain cannot. In addition, the lateral-axial relationship of the hybrid fiber reinforced polymer-confined cylinders depends on the arrangement of the fiber layers.