Effects of carbon nanotube enrichment of epoxy resins on hybrid FRP-FR confinement of concrete

The present research study is focused on the tensile testing and mechanical characterization of three different epoxy resins, reinforced with different concentrations of Multi-Walled Carbon Nanotubes (MWCNTs). The resins are used in crack repair of concrete members as well as in FRP sheet wrapping. The CNT reinforced polymers (CNTRP) showed a remarkable enhancement of their tensile strength (2.25 times over the host matrix) and deformation at failure (3.27 times over the host matrix). The CNTRP with the highest viscosity were used in a structural application, to impregnate glass FRP sheets to confine concrete cylinders. Then the specimens were wrapped with non-impregnated polypropylene fiber ropes (PPFR). The comparative results between specimens confined by the hybrid system, including glass sheets impregnated with epoxy resin or with resin reinforced by CNTs (CNTRP), are discussed. The specimen with CNT reinforced polymer showed 7.5% higher bearing load of the concrete until failure of the glass sheet, over the column with non-reinforced polymer. The gradual, smooth failure of the glass fiber CNTRP jacket took place at higher load levels than GFRP. Moreover, it presented half temporary load loss after the fracture of the glass sheet than the GFRP strengthened column. Finally, it indicated an earlier stabilization and regaining of the bearing load (27% earlier in terms of axial strain). (c) 2013 Elsevier Ltd. All rights reserved.