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%.

This paper is a contribution to the valuation of the millet stalk fiber as insulation material in building. To do this, the millet stem is crushed in two sizes and each size obtained is mixed with different Arabic gum content, which acts as a binder. Arabic gum is an effusion of sap from a trunk of acacias from Senegal. This material is still unusable largely because a big quantity is thrown in the nature. The influence of millet stem size and Arabic gum content on mechanical and thermal properties was evaluated. As for the resistance in flexion, we found a null value for all the samples. The compression resistance of samples varies from 0.8 to 1.5 MPa with a percentage of the binder evolving from 3 to 11.27 %. These values of the mechanical resistance are in strong proportionality with the binder dosages. The thermal conductivity varies from 0.113 to 0.914 W. m-1. K-1 with an effusivity going from 228 to 183 J.m-2. °C-1.s-1/2. The results showed that the conductivity and the effusivity increase with the content by linking of the material.

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.