QUALITATIVE ANALYSIS OF STEEL REINFORCEMENT BARS AVAILABLE IN THE CONSTRUCTION MARKET IN NIGERIA

Abstract

Construction industries requires steel (reinforcement bar) materials for a vast range of uses. These steel materials must satisfy the strength, stiffness and durability requirements specified by the standards and codes. The use of inferior quality and substandard steel reinforcement bars such as yield Strength, lesser nominal diameters, lesser elongation are among the causes of construction collapse and failures, hence the attempt to examine the quality of engineering materials used for locally produced normal / high strength steel and imported steel reinforcement bars. This research examined five different local manufacturers of ordinary/normal and Thermal Mechanically Treated (TMT) steel reinforcement bars sizes varying from (10, 12, 16 and 25) mm and (16 and 25) mm. Reinforcement bars imported from Ukraine are also available in the construction markets in Nigeria, these could be witness from all construction sites in Akure metropolis, the study Area. Digital Vernier calipers were used to validate various sizes of reinforcement bar. Specimen identified were cut and subjected to tensile test in accordance with BS4449 / 8110:1997, using Intron Universal Testing Machine. The mechanical properties such as yield stress (Py), the ultimate stress (Pu), the percentage of elongation, were identified and determined from the tensile tests. These results showed that they are in compliance with the BS 8110, Euro and NIS code. Also the chemical composition analysis indicated 98% iron content. These results show that 100% of all locally produced (Normal and TMT) steel reinforcement have manufacturer’s abbreviation and their names boldly written on all at least, one meter intervals, 98% of it has its yield strength fy > 500 N/mm2, accurate actual diameter, elongation >12, better ultimate to yield tensile ratio > 1.15, they all appear to be cheaper prices and they are all in compliance with both Nigeria industrial standard (NIS) fy = 500 N/mm 2 , Euro code fy = 500 N/mm 2 and British standard (B.S) fy = 460 N/mm 2 as against previous results obtained by (Arum 2008) where yield strength fy < 410 N/mm 2 , lesser actual diameter, percentage elongation 12%, ultimate tensile strength is 540 x 106 N/mm 2 , ultimate to yield tensile ratio < 1.15. This indicates that there are better quality and standard steel bars in Nigerian construction markets now than what it was used to be years ago. This study has equally created awareness of availability of locally produced high strength steel (HSS) TMT bars with fy > 600 N/mm2, with higher performance than the normal strength steel in Nigeria industries. Though relatively expensive than the normal strength steel but greatly cheaper than the imported steel which is a normal strength steel.