Axial behavior of concrete confined with flax fiber-reinforced polymers

Abstract In recent years, the use of synthetic fiber-reinforced polymer (FRP) composites has gained significant popularity in structural engineering. The confinement of concrete to improve its axial behavior has been one of the most encountered applications of such FRP materials. However, these synthetic materials are far from being friendly to the environment due to their significant carbon release during production. Besides, their high cost is still a major issue for the applications, especially in developing countries. Recently, research projects on the use of composite materials made of natural fibers have emerged in specific fields, such as the automotive and aircraft industries, due to environmental policies. The previous attempts of using natural materials for column confinement mostly rely on the use of conventional woven fabrics made of natural fibers. In this study, the FRP’s which include unidirectionally aligned flax fibers were used for the confinement of low-strength concrete. This composite material was either utilized alone or accompanied by glass or carbon FRP’s in the hybrid form. The results demonstrate that a considerable increase in strength and ultimate strain capacity is possible even for the specimens confined with only flax FRP. A higher enhancement was possible for hybrid forms.