Mechanical and Geotechnical Behaviour of Improved Sandy Clay Soil for Road Pavements in Offshore Sedimentary Basins

Road projects require a lot of earthworks.  Sometimes, the soil in place has an insufficient bearing capacity; hence, the need to look for soil with required specifications. When a material is too far from the construction site, its transportation costful and time spending to the project. In offshore sedimentary basins, materials mostly available are sandy clay soils. This paper focuses on the improvement of the bearing capacity of sandy clay soil for different road pavements. Two solutions were investigated: lithostabilisation of sandy clay soil with volcanic rocks and cement stabilisation at different percentage in various curing conditions.  Physical, geotechnical and mechanical properties were assessed on samples. It was found that, at 25% mix with volcanic gravel, sandy clayed soils are useable for the T2-T3 subbase layer and at 35% the mix can be stabilised with cement for the T2-T3 base and T4-T5 subbase layers. 4% cement dosage is the optimum for the three pavement layers. This dosage can be reduced to 2% for the T2-T3 subbase, if the negative impacts from environmental waters are counteracted. With a close look on the respect of prescribed procedures, sandy clayed soils in offshore sedimentary basins are useable for the construction of pavement layers.