Global bond behavior of enamel-coated rebar in concrete beams with spliced reinforcement

This paper presents an experimental study of vitreous enamel coating effects on the bond strength between deformed rebar and normal strength concrete. A total of 24 beam splice beam specimens were tested under 4-point loading with four parameters investigated: rebar size, lap splice length, coating and confinement conditions. As the splice length increases, the ratio of bond strength between coated rebar and black rebar was found to increase from 1.0 to a maximum value of 1.44 and decrease to 1.0. The maximum bond strength ratio corresponds to a splice length over rebar diameter ratio of 20–35 when the maximum elastic stress is developed in enamel-coated rebar. For a splice length over rebar diameter ratio of less than 20, an average of 10% bond strength increase was observed due to confinement provided by transverse stirrups. ncrete beams reinforced with enamel-coated rebar have a greater number of smaller flexural cracks than those containing black rebar since the enamel coated rebar can more effectively receives stress from the concrete.