Geotechnical properties of Qoz soils

Qoz Soils are wind blown deposits of fine silty sands which cover large areas in Mid-Western Sudan. The soils vary mainly in their silt content (7 to 25%). Several important infrastructure projects, such as the Continental Western Salvation Road, are under active development in Mid-Western Sudan. These important Structures will be supported on the relatively unfamiliar Qoz soils. This paper summarizes the basic properties of Qoz soils such as compaction properties, strength, compressibility and potential for collapse. Qoz soils attain relatively high dry densities when compacted. The maximum dry density increases linearly with silt content. The California Bearing Ratio CBR vary from 10 to 28% depending on the percentage of fines. The initial moisture content and silt content significantly affect the compressibility and collapse potential of these soils. The collapse potential may be rated as low to moderate.