Enhancing bonding behavior between basalt fiber-reinforced polymer sheets and concrete using resin pre-coating method and multi-wall carbon nanotubes

Abstract

There is a crucial problem of premature debonding failure in fiber-reinforced polymer (FRP) sheet external bonding reinforcement for concrete structures. Using anhydrous ethanol as solvent instead of acetone, the effect of resin pre-coating (RPC) technique with neat resin-ethanol solution and multi-wall carbon nanotubes (MWCNTs)-resin-ethanol solution on the bonding behavior of the FRP-concrete joints was investigated by single-shear tests. Experimental results indicated that RPC technique significantly enhanced the bonding properties, especially when the pre-coating was MWCNTs-resin-ethanol solution. In the case of using neat epoxy resin as adhesive, compared with the control specimens without RPC treatment, the ultimate bearing capacity, ultimate global slip, maximum bond stress and interface fracture energy of the basalt fiber-reinforced polymer (BFRP)-concrete joints using RPC treatment with MWCNTs-resin-ethanol solution increased by 32.6 %, 48.4 %, 68.3 % and 88.8 %, respectively. MWCNTs could be seen in scanning electron microscopy (SEM) images of the fracture surface, which indicated that they could penetrate into the concrete and the crack bridging and pull-out of MWCNTs could enhance the interfacial adhesion of the FRP-concrete joints. Compared with the RPC treatment using the restricted acetone, the RPC treatment with MWCNTs-resin-ethanol solution can more significantly enhance the bond properties of the interface between concrete and FRP sheet, and it is suitable for large-scale practical engineering applications on site. This study demonstrated the great promise of the RPC technique with MWCNTs-resin-ethanol solution toward practical engineering application in reinforcement and repair of concrete structures.