Using carbon nanotubes to improve strengthening efficiency of carbon fiber/epoxy composites confined RC columns

The effectiveness of using carbon nanotubes (CNTs) to enhance the strengthening efficiency of carbon fiber/epoxy composites confined reinforced concrete (RC) columns was investigated. A total of fourteen large scale rectangular RC columns were prepared and tested under concentric axial loading. The incorporation of CNTs within the carbon fiber/epoxy composites was achieved by modifying the epoxy resin using CNTs and/or coating the carbon fiber with CNTs enriched sizing agent. The failure modes, axial load-displacement responses, and microstructures of unwrapped, fully wrapped, and partially wrapped specimens were analyzed. Experimental results showed that using CNTs modified epoxy or CNTs enriched sizing agent improved the load carrying capacity and toughness of RC columns confined with carbon fiber/epoxy composites. Scanning electron microscopy (SEM) characterization showed that CNTs could improve the adhesion at the carbon fiber/epoxy interface and concrete/epoxy interface leading to improvement in the load transfer and load carrying capacity. (C) 2015 Elsevier Ltd. All rights reserved.