Effect of using carbon nanotube modified epoxy on bond–slip behavior between concrete and FRP sheets

Abstract

The influence of carbon nanotubes (CNTs) on the bond–slip behavior between concrete surfaces and fiber-reinforced polymer (FRP) sheets was investigated. A total of 30 concrete prisms were casted, reinforced with FRP sheets, and tested under double-shear test. Carbon or glass FRP sheet strips with different lengths and widths were externally bonded to the concrete prisms using either neat or CNT modified epoxy. The effects of epoxy type, fiber sheet type, FRP bond length, and FRP bond width on the bond behavior were investigated through the failure mode, bond stress versus slip curves, and scanning electron microscopy (SEM) imaging. Experimental results showed that using CNT modified epoxy resin enhanced the bond strength and ultimate slippage of the tested specimens. The enhancement was highly dependent on the type of epoxy and fiber sheet. The bond behavior between concrete surface and FRP was affected by bond length and width. Scanning electron microscope images 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 bond strength.