Assessment of the quality of reinforcing bars in the Ghanaian market a case study of the Western Region

Abstract

Building materials are the main component of the construction industry hence its quality and characteristic are essential. It is expected that building professionals select materials with adequate properties that are fit for purpose and meet acceptable local and international specifications. A study in a Nigeria ranked substandard building materials as the second leading causes of building collapse in Lagos. Hence this study seeks to assess the quality of the mechanical properties of local and foreign reinforcement bars (12mm 16mm and 20mm diameter) in the opening market of Sekondi-Takoradi. Samples were sourced from three major retail companies namely K. Ofori, B5 Company and Sethi Takoradi Limited. Samples were cut to a length of 500mm and tested for their tensile properties at the mechanical laboratory of Ghana Standard Authority in Accra. The result indicated that, the average yield strength for mild steel rods was 318N/mm² which was greater than the minimum provision. All 16mm and 20mm diameter high tensile steel bars exceeded the minimum yield strength; however 12mm did not meet the required yield strength. Both mild steel and high tensile steel samples recorded ultimate tensile steel values greater than the BS 4449 & GS 788-2 minimum provision. Similarly both mild steel and high tensile steel samples recorded an average elongation of 29% and 25% respectively. Mild steel samples recorded ductility of 1.24 while high tensile steel recorded a ductility of 1.44. 12mm and 20mm diameter samples were approximate to the standard nominal size provided by the BS 4449 & GS 788-2 specification. Meanwhile all the high tensile steel samples were below the nominal diameter provision of area of steel. The research conclude that mild steel rods may not be the causes of building collapse, while high tensile steel bars results suggest inconsistent qualities standard. All high tensile steel samples did not meet the required nominal area of steel and may partly be responsible for the collapse of buildings.