Geotechnical Characterization of Subgrade Soils along the Baneah-Donkeah Road Section for Pavement Design

Résumé fourni par la source

Road infrastructure is essential to economic development, yet many road sections in Guinea deteriorate prematurely because of insufficient geotechnical characterisation of subgrade soils, particularly in tropical lateritic contexts. This study assesses the geotechnical suitability of the subgrade soils of the Baneah-Donkeah road section, which provides access to the Banéah and Donkéah hydroelectric plants in Kindia Prefecture, Republic of Guinea. Five hand-dug test pits and dynamic cone penetrometer soundings were carried out along the 10 km section. Soil samples were tested for natural water content, specific gravity, particle-size distribution, Atterberg limits, modified Proctor compaction and soaked California Bearing Ratio (CBR). Soils were classified predominantly as GTR classes B4 and B6, with plasticity indices between 12% and 25%. Modified Proctor maximum dry density ranged from 2.10 to 2.146 t/m³. CBR values exceeded 60% for most samples (subgrade class PF4), except sample PM3-E2 (CBR 38%, class PF3). The subgrade soils of the Baneah-Donkeah section are, overall, geotechnically suitable for road construction, although their high fines content requires strict moisture control, adequate compaction, and, for the most plastic sample, lime treatment.