Strengthening of plain concrete cylinders with hybrid composites based on basalt and sisal fiber systems

Abstract

Strengthening and rehabilitation of concrete structures are becoming popular in the construction industry using synthetic fiber reinforced polymers (FRP). However, it has a major drawback due to their economic and environmental impacts. The study focuses on investigation of strength and ductile behavior of concentrically loaded hybrid sisal basalt FRP (HSBFRP) confined concrete structures. A combination of natural sisal and basalt fibers were proposed as the hybrid system. Confined concrete cylinders with different layers of hybrid FRP systems were subjected to various strength tests and test results proved that hybrid FRP confinement intensify the axial load-carrying capacity compared to unconfined specimens. A relative performance analysis of hybrid sisal-basalt FRP confinement with basalt and sisal individual FRP confinements was performed. From the test results it was noticed that the ultimate load carrying capacity increased by 63% along with a fracture energy of 23.17 MPa when the cylinders were confined with 5 layers of hybrid confinement. When compared with unconfined specimens the ductility index attained a maximum value of 4.31 when confined with multiple layers of sisal and basalt FRP wraps. It was proved that with the concept of hybridization in confinement, there was a significant enhancement in fracture energy and ductility index for concrete, thus preventing catastrophic failure.