Strength, Ductility and Chemical Properties of Reinforcing Steel Bars in Ghana’s Building Construction Industry

Abstract

The steel manufacturing industry in Ghana has grown rapidly in the last decade. Local steel milling companies are taking advantage of the readily available scrap metals as raw material to produce reinforcing bars. Major steel importers also continue to import reinforcing bars into the country to fill the gap between production and demand of steel reinforcing bars in Ghana. The question of whether these locally milled and imported reinforcing bars meet internationally accepted standards remains unanswered. This original research investigated the mechanical and chemical properties of reinforcing bars available in the Ghanaian market. A total of 700 samples of 12mm-25mm nominal diameter reinforcing steel bars were collected from three major steel bar distributors and construction sites in Accra. The reinforcing bars sampled represented steel bars from four local milling companies and imported steel from Ukraine. Yield strength and maximum tensile strength of mild steel reinforcing bars milled in Ghana ranged from 328.26 N/mm2 to 487.41 N/mm2 and 487.41 N/mm2 to 598.42 N/mm2 respectively. Moreover, the high yield reinforcing bars recorded yield strength ranging from 341.93 N/mm2 to 702.83 N/mm2 and tensile strength ranging from 497.36 N/mm2 to 815.67 N/mm2. All the reinforcing bars recorded carbon contents higher than the maximum requirement of 0.24% and 0.22 - 0.32% in the British and Ghana specifications, respectively. The local milling companies need to improve on the milling process to remove excess carbon from the steel bars in order to improve on ductility.