Strengthening of Recycled Aggregate Concrete with Novel Natural Banana Fiber Rope Confinement

Abstract

This study investigates the effectiveness of banana rope confinement, a biodegradable and low-cost natural fiber technique, in enhancing the compressive behavior and seismic performance of concrete incorporating recycled materials. An experimental program was conducted on cylindrical specimens (150 mm × 300 mm) comprising natural aggregate concrete, rubberized concrete, recycled concrete aggregate (RCA) concrete, and recycled brick aggregate (RBA) concrete. Specimens were confined using one to three layers of banana rope applied through a wet lay-up technique with epoxy bonding and tested under axial compression. In addition, more than 50 existing analytical confinement models were evaluated for their applicability to banana rope-confined concrete. The results indicate that banana rope confinement does not influence the initial stiffness due to its passive nature, but significantly enhances compressive strength and ductility. Strength improvements reached 35.06% and 30.39% for natural and rubberized concretes, respectively, while RCA and RBA concretes exhibited substantially higher gains of 100.57% and 130.16%. Ultimate strain and dissipation increased markedly, particularly for recycled aggregate concretes, demonstrating superior ductility. Analytical evaluation revealed that existing models reasonably predict the strength of natural and rubberized concretes but significantly underestimate the behavior of recycled aggregate concretes.