Comparative Evaluation of the Mechanical Properties and Chemical Composition of Reinforcing Steel Bars Produced by Libyan Mills

Abstract

The quality of reinforcing steel largely determines the safety and durability of reinforced-concrete structures, yet the increasing number of private rolling mills in Libya has raised questions about consistency with accepted specifications. This study evaluates and compares 12 mm reinforcing bars from two Libyan producers, Sidi Al-Sayeh (SS) and Misurata Iron and Steel (MR). Hardness, tensile behaviour (three specimens per mill), dye-penetrant inspection, radiography and handheld X-ray fluorescence (XRF) analysis were carried out. Hardness was 114 HB (SS) and 124 HB (MR). Mean yield strength was 389 ± 4 MPa (SS) and 338 ± 29 MPa (MR), and mean tensile strength was 565 ± 8 MPa and 495 ± 40 MPa, respectively; both fall inside the indicative ranges for normal-strength bars (250–400 MPa and 400–600 MPa). Elongation, however, was only 7.4 % (SS) and 5.4 % (MR), well below the 12 % minimum, and the SS hardness lies slightly below the 120 HB lower bound. Dye penetrant revealed small surface indications in both bars (more pronounced in SS), while radiography showed no internal flaws. The XRF analyses indicated 98.02 % (SS) and 98.77 % (MR) iron with minor differences in Mn, Cr and Co; carbon and sulphur could not be quantified. Both products therefore satisfy the strength criteria but show limited ductility. Larger sampling, full chemical analysis by optical emission spectrometry and testing of unmodified bar diameters are recommended.