Effect of glass fiber sheet in adhesive on the bond and galvanic corrosion behaviours of CFRP-Steel bonded system

Abstract

Steel structures strengthened with CFRP composite may have potential galvanic corrosion issue. It was recommended that a layer of glass fiber sheet (GFS) be embedded in the adhesive layer to protect the CFRP-steel bonded system against galvanic corrosion. But the inclusion of GFS in the adhesive may negatively affect the bond behaviour between steel and CFRP. This paper investigated the effects of GFS on the corrosion behaviour and bond characteristics between steel and CFRP. Three types of experimental testing on CFRP-steel double strap joints with/without GFS were conducted, including accelerated corrosion testing, static and fatigue testing. Accelerated corrosion testing was carried out to justify the effectiveness of GFS in preventing galvanic corrosion of CFRP-steel bonded system. Static tension testing and fatigue testing were carried out to quantify the effect of GFS on the static and fatigue bond behaviour between steel and CFRP. The effects of GFS on the corrosion rate, failure mode, joint capacity and fatigue life were reported. Experimental results suggested that GFS may reduce the fatigue performance of the bond between steel and CFRP, although GFS may slightly improve the static bond behaviour. It is recommended that GFS can be included in the adhesive layer as an additional protection against the galvanic corrosion hazard in the CFRP-steel bonded system, provided that the system has no concern of fatigue loading.