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.
