Abstract
External bonding of steel plates to structural concrete members has widely gained popularity in recent years, particularly for repairing and strengthening reinforced concrete beams. The success of this bonding technique depends on the effectiveness of the surface preparation of the steel and concrete beams. Studies have shown that most of the beams strengthened using this technique usually fail prematurely by debonding. In this study, concrete beams with different types of surface preparations were investigated, such as no surface preparation (NSP), wire brushing (WB), scabbling (SC) and hand chipping (HC). The quality of the surface preparation established was measured based on the flexural performance of the externally strengthened steel-concrete beams. Eight (8), 250x450x3600 mm reinforced concrete beams were prepared and strengthened with glued steel plates on their soffits. All the specimens were tested under two-point static loading and failure modes were observed. The results showed that beams with rougher surface preparation have a high bond strength as compared to smoother surface preparations. The increase in the average capacity of strengthened beams with the surface prepared by hand-chipping, scabbling, wire brushing was found to be 75.3%, 67.5% and 46.9% respectively, compared to the capacity of the beam strengthened without surface preparation.