In Senegal, as in most Sahelian countries, the majority of pavement beds are of lateritic or basaltic gravelly material. These types of materials become scarce, become more expensive and lose their mechanical performance year after year. The possibility of using the silexite material, from the residues of the phosphates exploitation of the Chemical Industry of Senegal which are available in quantity remains a favorable asset if it respects the technical specifications for a road material all the more as Senegal is currently planning major road infrastructure projects. Thus, in this study, it was proposed to carry out extensive research on the geotechnical performance of this silexite material in the form of a severe 0 / 31.5 crushed material in order to deduce its suitability for use as a base course. First the material coming from the heap is tested first according to an experimental study of complete identification of the material. It turns out that the results were not satisfactory considering the value of the IP 41.5 plasticity index. very high, a very low CBR index of 16.67, a high methylene blue value of 2.6 and a granulometric curve coming out of the acceptance zone. The results did not meet the technical requirements and specifications expected because they are very contaminated by other foreign bodies. Nevertheless, a study to improve the cement material is discussed at 1%, 2%, 2.5% and 3%. The CBR indices found are respectively 127.60, 287.92, 298.77 and 373.46 with plasticity indices that vary between 27.65 and 34.35%. The characteristics of the material have improved significantly in terms of CBR and a decrease in the IP is noted that passes from 41.5 to 27.65 while being out of tolerance. The study is continued using granular fractions from industrial crushing to reconstitute crushed gravel 0 / 31.5. The results were conclusive as the particle size curve fits perfectly into the acceptance zone. An IP value of 19.99% is obtained certifying a good possibility to use the material in foundation layer but not in base layer. A CBR index of 149.27 and a density of 2.01 meeting the specifications required for its use in bedding.