Characterization and Variability of Bending and Fatigue Properties in Reinforcing Steel Bars Made From Scrap

Abstract

The variability of mechanical properties of reinforcing steel bars manufactured from scrap metals by local manufacturers in Kenya was investigated in this research. The key properties were bending and fatigue. Information available on Kenyan rebar behaviour so far has been scant and inadequate. Such information could be used for optimizing concrete structural design and possibly avoiding the frequent collapse of structures in Kenya. The bars tested were purchased from two local rolling mills. Laboratory tensile tests, bend/rebend test, chemical composition analyses, microstructure examination and hardness tests were carried out on a set of bar specimens. The results were compared with the existing set standards for speci ed class of reinforcing steel bars and non-conforming variability discussed. Bars from one rolling mill were seen to fail outright in the tensile test. All bars passed the bend/rebend test, with 0% CoV. Toughness was established by nding the area under the tensile test curve. Most of the tested properties had a coe cient of variation under 10% except for percentage elongation and toughness whose CoV rose to over 30%. In view of the source A bars that failed the tensile strength test, it is recommended for the rolling mills to add the grain re ning alloying elements vanadium and nickel.