Articles

Contribution to the Study of the Chemical and Microstructural Quality of Reinforcing Bars in DR. Congo “Case of the City of Lubumbashi”

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: This research highlights the contribution to the study of the microstructural quality of reinforcing bars on the Lubumbashi market including bars imported from South Africa (FA), Zambia (FZ) and those produced locally ( FC) by the only steel industry, in the former province of Katanga, the iron processing company SOTRAFER, in acronym.

The samples of the locally produced reinforcement bars (FC) were collected at SOTRAFER at the end of production, while the samples of the FA and FZ reinforcement bars were taken randomly on the Lushois market in a hardware store specializing in sales to avoid errors.Microstructural analysis of all bars revealed a similar microstructure consisting of a ferrite (light areas) and pearlite (dark areas) matrix and a ferrito-pearlitic structure. This microstructure, as predicted by the Fe-C equilibrium diagram, could be justified by the carbon content (lower than the eutectoid point content); the results prove that all bars are hypoeutectoid steels (%C ≤ 0.77). They can also be assimilated to the category of mild steels (0.1 ≤ %C ≤ 0.25). This also shows that all the bars have not undergone a particular heat treatment and have been cooled very slowly in order to allow the diffusion of atoms and reach equilibrium conditions. The results obtained from the variance analyses of different materials of dimensions of 10, 12 and 16 mm revealed that at the level of chemical and mechanical analyses, there was no significant difference on all the parameters studied and that all the reinforcement bars could perfectly be used in construction. Finally, the survey reveals that FA is reputed to be of better quality among consumers, for several reasons including the psychological one although its price is lower than that produced locally.

Evaluation of the Quality of Reinforcing Bars on the Market in the City of Lubumbashi in DR Congo

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This research highlights the evaluation of the chemical and mechanical quality of reinforcing bars on the Lubumbashi market including bars imported from South Africa (FA), Zambia (FZ) and those produced locally (FC ) by the only steel industry, in the former province of Katanga, the iron processing company SOTRAFER, in acronym.

Indeed, this iron production sector is unexplored in the Democratic Republic of Congo while we are in the era of its reconstruction. Consequently, this sector leads us to an almost total dependence on imported iron (steel) because the latter is known throughout the world as the engine of development of modern societies. The samples of the locally produced reinforcing bars (FC) were collected at SOTRAFER at the end of production, while the samples of the FA and FZ reinforcing bars were taken randomly on the Lushois market in a hardware store specializing in sales to avoid errors.

The chemical characterization showed that the three natures of the reinforcing bars are similar with all the elements in the ISO 9001 standards which are Fe, Mn, Cu, Si, C, Cr, Ni, Mo, P, S, Nb, Co, Ti, V and Al except three chemical elements such as Mo, Ni and Cu. This difference is, however, attenuated by the equivalent carbon content. The mechanical characterization showed that all the different materials studied comply with the ISO 6898 standard. The high values ​​of the elastic limit resistances of 16, 12 and 10mm in diameter are observed respectively in the FC samples (436N/mm²); FA (450N/mm²); FC (475 N/mm²). These behaviors are also observed in the plastic phase.