Behavior of concrete confined with epoxy bonded fiber ropes under axial load

Abstract

In the past, several experimental and theoretical studies investigated the axial compressive strength and strain of plain concrete (PC) externally confined with natural and synthetic fiber reinforced polymer (FRP) composites. Typical types of synthetic FRP(s) are aramid, glass, carbon, PEN (polyethylene naphthalates) and PET (polyethylene terephthalate), whereas natural FRP(s) include flax, sisal, hemp and jute. In this article, the performance of a novel, low-cost and sustainable strengthening technique i.e., fiber rope reinforced polymer (FRRP) composites to enhance the axial compressive strength, strain and deformability of concrete specimens through external wrapping is explored. The outstanding benefits of the newly proposed FRRP composites are low-cost, wide availability, easy application and more environmentally friendly. In this research, 39 circular plain concrete (PC) cylinders were tested to failure under uniaxial compression. The research parameters covered fiber rope type (such as hemp, cotton and polyester) and number of FRRP layers. Experimental results proved that external confinement by using FRRP is very effective to enhance ultimate strength, strain and deformability of the concrete. Further, based on the test results, the implementation of the existing ultimate compressive strength and strain models established for the synthetic and natural FRP(s) is evaluated to assess their application to the newly proposed FRRP confinement. It is found that more or less all considered models do not accurately predict the tested ultimate compressive strength and strain of the FRRP-confined concrete. In the end, new ultimate strength and strain models are proposed to accurately predict the ultimate compressive strength and strain of concrete specimens confined with fiber rope reinforced polymer composites. The predicted ultimate compressive strength and strain values compare favorably with the experimental results of the present study. © 2020 Elsevier Ltd