Mechanical properties and microstructural analysis of reinforcement steel bars in Osun State construction industry

Abstract

Steel bars are crucial components in structural engineering. The frequent incidents of building collapse in Nigeria highlight the importance of carefully analysing the characteristics of reinforcement steel bars available in the local market. A study was conducted in Osun State to evaluate the compliance of locally available steel bars with essential standards, addressing concerns related to building integrity. The study examined the mechanical properties of reinforcement steel rods with diameters of 7, 9, 12, and 14 mm, procured from four prominent dealers in the Osun State market. Standard procedures were employed to determine hardness values, yield strength, and ultimate tensile strength, utilizing an Instron Satec Series 600DX universal testing machine. Additionally, Scanning Electron Microscopy (SEM) was employed to investigate microstructural properties at the metallurgy laboratory of SARD and the Department of Materials Science and Engineering, Obafemi Awolowo University, Ile-Ife, Osun State. The findings showed that certain steel bars exceeded the hardness values, yield strengths, and ultimate tensile strengths set by BS4449, ISO, NIS, and ASTM A706. However, the studied steel bar samples showed commendable ductility. A strong correlation was established between microstructure and mechanical properties. It is noteworthy that the samples contained obvious levels of impurities. In conclusion, while the samples demonstrated satisfactory ductility, it is important to take into consideration the presence of impurities.