Durability of Chemically Treated Plastic Soil for Unpaved Roads

Unpaved roads are subject to rapid deterioration and large deformations under mechanical and environmental stresses that can render them impassable. Prior work has shown that plastic soils can be mixed with a polymeric chemical admixture to create a hydrophobic material and potentially minimize these issues. The purpose of this work is to assess the durability of a low plasticity clay soil treated with a chemical admixture by evaluating changes in physical and mechanical behavior when subjected to alternating cycles of wetting and drying. Volumetric change, water content change, and mass loss were measured at the completion of each one of up to twelve wetting and drying cycles. Unconfined compression tests were performed after select cycles to assess changes in mechanical properties. Tests were also performed on specimens stabilized with Type I/II portland cement for comparison. It was found that the specimens with chemical admixture treatment survived a full twelve cycles of wetting and drying. The volume changes of the specimens were small (±2 %) and there was no apparent reduction in strength. The chemically stabilized soil retained its physical and mechanical properties in a manner comparable to cement stabilization of the same soil. These results suggest that the CAT produces a sufficiently stable material when subjected to alternating wetting and drying conditions and has potential applications in improving long-term performance of unpaved roads.