Kocouvi Agapi HOUANOU^1,, Koutchika Roger DANVI¹, Kpomagbé Serge DOSSOU¹, Emmanuel OLODO¹

Faced with the growing shortage of conventional materials in road construction in South Benin, this study explores the valorization of the silty sand of Tohouè, an abundant local resource but unsuitable for the raw state because of its low lift and its sensitivity to water. The general objective is to evaluate the effectiveness of mechanical stabilization by adding Dan's 0/31.5 granite crusher to allow its use in road construction. The methodology consisted in formulating eight mixtures with crushed contents ranging from 10% to 45%, characterized by standardized geotechnical tests: particle size analysis, Atterberg limits, methylene blue value, modified Proctor and CBR index after immersion. The results demonstrate a gradual improvement in mechanical properties. The mixture with 20% crushed material already shows a marked improvement with a CBR of 58.4% and a density of 1.99 g/cm³, meeting the CEBTP standard. However, it is the 25% blend that constitutes the technical optimum, achieving a CBR of 63.65% and a density of 1.995 g/cm³, fully meeting the requirements of international standards for foundation layers. Therefore, stabilization with 25% granite crushed represents the optimal formulation, offering the best compromise between mechanical performance and economic viability. This solution allows a 75% saving on the use of noble materials while valuing an abundant local resource, thus constituting a sustainable alternative for road construction in Benin.

silty sand, crushed granite, geotechnical tests, foundation layers, stabilization