Effects of Source of Reinforcement on Microstructure and Strength Characteristics of Reinforced Concrete Beams

Abstract

This paper is a report of investigations carried out on reinforcing bars obtained from six sources, to determine their strength adequacy for structural applications, with a view to curbing the incidence of structural failures attributable to the use of substandard reinforcement. The parameters investigated are the: micro-structural analysis, tensile strength properties, and their flexural performance in beams. The chemical analysis of the samples was carried out using Optical Emission Spectrometer (OES). The micrographic analysis was carried out using metallurgical research microscope. 600mm length specimens of reinforcing bars of the six different steel was used for the tensile strength using tensile machine. For the flexural strength, 150 mm x 150mm x 750mm beam specimens was used. The beam specimens were reinforced with the six different reinforcing steel. The results revealed that only two of the locally sourced steel and all the foreign-based steel met the requirement for use as high steel, but none of the foreign-based steel met the minimum requirements of elongation. Also none of the steel tested fully complied with the chemical and metallurgical standard in terms of carbon content and carbon equivalent value. However, all the foreign-based steel specimens tested displayed a superior load-deflection characteristic compared to the locally-sourced steel samples. From the results of this investigation, it can thus be concluded that all reinforcing steel designated as high yield should be subjected to further testing before use so as to ensure compliance with the prevailing codes.