Evaluation of surface geometries and physical properties of concrete reinforcement steel rods rolled in Nigeria

Abstract

The objective of this research was to evaluate the surface geometries and physical properties of locally-rolled steel rods made from billets that are produced from locally-sourced scraps and three available imported rebars in Nigeria. The database of test results obtained were compared with specifications in NIS 117:2004 (local) and BS 4449:2005 and ISO 6935-2: 2007 (international) standards. There are 26 indigenous rolled samples that are available in Nigeria of which two samples were from imported billets but rolled locally, five (5) were Thermo-Mechanically Treated (TMT) and the remaining 19 were ordinary rods (without any form of heat treatment). The average measurements of fifteen samples selected at random from each brand were taken. Their measurements were taken and computed for full length, nominal diameter, cross-sectional area, mass per length, rib height, transverse rib inclination, rib spacing, rib flank inclination, relative area, longitudinal height and rib base width. These data were systematically documented to study their qualities. Findings showed that none of brands fully conformed to the three standards in terms of diameter and cross-section area. Out of the ordinary locally-rolled rods, Brands 7, 10, 16 and 18 were the best in terms of conformity. Among the TMTs, Brand 6 B was the best in performance. The two selected rods, Brands 20 B and 21 (locally-rolled from imported billets) performed well by meeting four (4) of the specifications for surface geometries and physical properties. Among the imported steel rods, Brand 24 gave the best performance in specifications for surface geometries and physical properties. Keywords: Surface geometries, Thermo-Mechanically Treated, Scraps, Billets