Papa Sanou Faye^1,, Adama Dione², Issa Ndoye², Saliou Pene¹, Fatou Samb³, Ibrahima Khalil Cissé⁴

Lateritic gravels (LG) constitute a strategic material for road construction in Senegal. This study aims to map and perform a geotechnical characterization of lateritic borrow pits from the Dakar and Thiès regions, in order to assess their suitability for use in sub-base and base layers of road pavements. Physical and mechanical tests were carried out on laterites from nine sites in their natural state, and after stabilization with 1%, 2%, and 3% cement. The results show that most laterites from the Dakar and Thiès regions except those from the Ngoundiane and Lam-Lam quarries, which exhibit excessive plasticity (PI > 25%) are suitable for use as sub-base materials (CBR > 30%). However, most of them do not meet the CEBTP and AGEROUTE standards for base course applications. After cement stabilization at 1%, 2%, and 3%, the CBR values range between 54% and 374.53%. Laterites from Toglou 1, Sindia, and Tchicky can be used as base course materials (CBR at 95% > 80%, and in some cases > 160%) starting from 2% cement content, while all laterites become suitable from 3% cement, except Lam-Lam, which meets specifications only at 4% cement content. Unconfined compressive strength (UCS) tests on cement treated laterites (1%, 2%, and 3%) yielded results that comply with CEBTP (1984) standards (1.8 < Rc < 3.0 MPa). In terms of tensile strength, only the Sindia, Toglou, Yeba, and Tchicky quarries met the CEBTP criterion (Rt > 0.3 MPa) after 3% cement treatment.

Geotechnical mapping, lateritic gravels, CBR, base course, sub-base, borrow pits, Dakar, Thiès, Senegal