Mechanical Characteristics Test of Concrete Steel Bars Available in Côte d’Ivoire

Abstract

Buildings collapse has now become a recurrent phenomenon in C ô te d’Ivoire. Therefore, this study was conducted to find out the reasons for these disasters, and check in particular to the extent, and concrete steel bars produced in C ô te d’Ivoire and used in buildings’ structures are involved. Samples having 6, 8, 10 and 12 mm in diameter steel taken from the five (5) major manufacturers or suppliers of the Ivorian market were subjected to physical, chemical and mechanical tests to determine their performance. A comparison of these results with the NF EN 10080 and NF A35 080-1 standards made it possible to calculate the probability to have out-of-standard products in a structure. Pieces having 60 cm were cut from three bars of the same thickness and then subjected to tests. These are the chemical test by optical emission spectrometer, physical tests by caliper measurements of diameter, height of bolts and ribs and calculation of linear mass, and tensile tests with the help of hydraulic press. These tests made it possible to determine the characteristics of the steel bars. Then, these characteristics were compared with standards NF EN 10080 and NF A35 080-1, in order to judge their conformity for construction. Finally, the likelihood of having non-standard steel bars in a structure is calculated. These tests indicate that the relative surfaces of the bolts of the various bars HA6, HA8, HA10 and HA12 vary from 0.146 to 0.323 respectively; 0.120 to 0.312; 0.101 to 0, 297 and 0.142 to 0.482. Likewise, their calculated linear masses of these bars are respectively between 28.3 mm 2 and 222 g/m; 50.3 mm 2 and 395 g/m; 78.5 mm 2 and 617 g/m; and 113 mm 2 and 888 g/m. In addition, their yield strengths and elongations at break vary from 344 MPa to 582 MPa and from 0.2% to 15% respectively. According to analysis of these results, 100% of steel bars would lead to a steel-concrete adhesion that complies with standard requirements and 100% have a linear mass or density lower than the standard. Similarly, on the mechanical aspect, 70% of steel bars have a yield strength lower than 400 MPa and 95% have an inappropriate ductility. Non-compliance with cross-sections, inadequate performance and non-compliance with the chemical composition of steel bars expose buildings to low durability and even sudden collapse of their structural elements. Concrete steel bars contribute a great deal to failures found in buildings.