This article presents the study of the behaviour of reinforced concrete steels, used in constructions in Senegal, under the effect of corrosion. The study is carried out on locally manufactured steels from three (03) companies located in Senegal and on control bars imported from France. Type 1 (E1), Type 2 (E2) and Type 3 (E3) steels are locally manufactured and Type 4 (E4) steels come from France. For each type of steel, samples with diameters of 8 mm, 10 mm and 12 mm were used. Mass losses were evaluated after immersion of these samples in a corrosive solution. For each type of steel and for all the diameters studied, the corrosion rate that initiates cracking of the asphalt concrete was evaluated from the actual diameter of the bars and the thickness of the nominal coating. From the mass lost over time, correlations between duration and mass loss were established for all diameters of the different types of steel. These relationships made it possible to calculate the time required to reach the corrosion rate that initiates concrete cracking. The results indicate that 66.67% of the steels studied, of local manufacture, have a corrosion time that initiates cracking of concrete lower than that of the control bars imported from France. Type E1 steels with a diameter of 8 mm have a duration to reach the corrosion rate that causes cracking of concrete, equal to 49.71% of the duration of type E4 steels. These results indicate that the steels used in construction in Senegal do not have the same behaviour vis-à-vis corrosion.

The main object of this study is to optimize the use of crushed sand from basalt aggregates and sand dune in hydraulic concrete. In this sense, we have studied a series of tests, of partial and/or total substitution of sand dune by crushed basalt sand, with a W/C ratio (water/cement) of 0.49. The study consists to assess the rheological and mechanical properties of the concretes (C1, C2, C3, C4, C5, and C6) with respective substitution rates of (0%, 20%, 40%, 60%, 80% and 100%). The results are then compared and discussed. The best workability is given by sand dune concrete (C1). The mechanical resistance of C6 is superior to that of C1, on the other hand the workability of C1 is greater than that of C6. The mixes based on partially substituted aggregates give the best compressive strength performance compared to those based on fully substituted aggregates (C1 or C6). Maximum compression is obtained at 20%.

The behavior of Fe500-3 iron was studied in the interstitial solution of mortar concrete, formulated from sand, cement, water, admixtures and in the presence of a clay (attapulgite) added as corrosion inhibitor. Indeed, in most cases in Senegal, mixing water and sand used in concrete formulations for buildings are subject to no treatment. The study solution was synthesized from these concretes at the 3rd, 7th and 28th day of wet cure. Fe500-3 iron corrosion tests in the interstitial concrete solution were carried out by monitoring the free corrosion potential, Tafel polarization curves and electrochemical impedance spectroscopy measurement. The protective power of attapulgite was also evaluated by electrochemical methods with different levels of inhibitor (0 to 20%). The measurements reveal a probable attack of Fe500-3 iron at the 3rd and 7th day of cure in the absence of inhibitor and the protective effect of the interstitial solution of the concretes without inhibitor at the 28th day of cure by the formation of a protective layer on the iron surface. The results also showed the corrosion inhibition effect of the clay on the 3rd and 7th day of cure by the formation of a protective film on the surface of the metal. The layer thickness increases with the content of the clay. A maximum average inhibitory efficiency of about 87.8% was obtained at the 7th day of cure at the 20% clay content.

Senegal has at its disposal a lot of mineral deposits among which the clay. This material is usable mostly in the production of pottery, the manufacture of bricks or tiles. Nevertheless, the increasing use of some natural aggregates in construction, more accurately gravels like basalt as well as limestone, could expose them to depletion. It is within this framework that our research, which is about the thermo-mechanical study of clay gravel-based concrete, has been developed. It consists of replacing common gravels with expanded clay aggregates. To that end, we have tested the clay of Thicky, which the SOFAMAC factory uses to manufacture its building materials. We used different methods to get expanded clay aggregates at different temperatures. We also did the characterization of these expanded clay aggregate as well as that of clay concrete. The results obtained from the gravels have been compared with those from common concretes. They indicate that the use of these gravels bring satisfactory results when they undergo an adequate transformation.