Bond behavior between CFRP and corroded steel plate associations with surface treatments

This study focused on the interfacial bond behavior of steel-CFRP (carbon fiber-reinforced polymer) adhesion joint associations with different steel surface treatments through typical pull-off and shear tests. The specimens were fabricated based on wet layup laminating CFRP and clean/corroded steel plates. Four types of surface treatments and two kinds of pre-coating processes were investigated to optimize the interfacial bond behavior. Meanwhile, the conventional rust removal methods were also studied by clarifying the physical and chemical characteristics of steel surfaces. Test results evaluated the topography, microstructure, and surface composition of clean and corroded steel specimens, and qualitatively established their relation to bonding behaviors and failure modes. A strong correlation existed between the surface geometry properties and the tensile/shear strength, however, for clean and corroded steel surfaces their fracture mechanisms differ. Various physical property parameters of the corroded surface related to surface treatment will further affect the bond performance. The corresponding adhesion mechanisms were mathematically demonstrated based on the surface energy principle. The present experimental results provide new insights into the interfacial bond mechanism between corroded steel structures and adhesive or CFRP composites. • Corroded steel-CFRP strengthening technique was optimized by multiscale analysis of the interfacial bond behavior. • Effects of four de-rusting methods on the physical and chemical characteristics of steel surfaces were evaluated. • Relationship between steel surface topography and tensile/shear bonding properties were qualitatively established. • Steel-CFRP interfacial bond mechanisms of the clean and corroded cases were investigated and compared.