Strength and Deformational Characteristics of Concrete Beams Reinforced with Steel Bars Locally Produced from Recycled Metal Scrap in Ghana

Abstract

This study was conducted to examine the structural behavior of concrete beams reinforced with local steel bars available in Ghana. The concrete was prepared from conventional materials of ordinary Portland-limestone cement, pit sand and granitic stones. Steel bars of sizes 12mm, 10mm, and 8mm from different millers used to reinforce the concrete beams were tested to study the stress-strain relationship of the bars. The main reinforcing steel bars in the concrete beams comprised 12mm high tensile and 12mm mild steel bars produced by four different companies. The four companies from which these steel bars were obtained are Ferro Fabric Limited (FFL), United Steel Company (USC), Sentuo Steel Limited (STS) and Fabrimetal (FAB). The specific objectives of this study were to determine the actual strength and sizes of steel bars used to reinforce concrete (steel bars of nominal sizes 12mm, 10mm and 8mm from different millers), to study the stress- strain relationship of the bars, to study the ultimate limit state characteristics of beams reinforced with different bars and to investigate the deformational behaviour of concrete beams reinforced with different bars (i.e., cracking, deflection).  Data collected were analyzed using theoretical and experimental approaches. The experimental results confirmed theoretical analysis that indicated that governing failure loads of the beams were due to steel yielding first with the exception of one beam in which the governing failure load was by shear. On average the experimental cracking and failure loads in the beams reinforced with high-yield steel bars were slightly higher than the theoretical loads, while they were observed to be slightly lower in the beams reinforced with mild steel bars. With regard to cracking, the beam reinforced with FFL ribbed mild steel developed the highest number of cracks at failure which represent a very good bonding between steel and concrete as compared to the other companies. Beams reinforced with FAB high-yield steel had the highest failure load as compared to the other steels. It is important to ensure standardization of the rebars in the Ghanaian market such as the size of the bar, the rib spacing, and the rib height through the dissemination of information to stakeholders including structural and material engineering manufacturing companies and contractors.