Lime stabilization is a widely used technique to improve weak subgrades; however, its effectiveness under freeze-thaw cycles remains a critical challenge. This study investigates the incorporation of cementitious materials to enhance the mechanical properties and environmental resistance of lime-stabilized soils under such conditions. Two types of soils, gray shale (plasticity index of 37.8) and clay soil (plasticity index of 19.0) from Nebraska, were used. Stabilization mixtures included lime dosages of 0%, 3%, and 6% by weight, combined with either 10% fly ash or 3% and 6% cement by weight. The experimental program comprised three stages: characterization of physical properties, preparation of composite specimens for unconfined compressive strength (UCS) testing, and evaluation of environmental resistance through freeze-thaw cycles (7 cycles after 14 days of curing and 12 cycles after 28 days of curing). Results showed that lime and fly ash significantly reduced the plasticity index of gray shale, with less pronounced effects on clay soil. Cement-lime stabilization demonstrated superior UCS retention and resistance to freeze-thaw cycles for both soil types, outperforming lime alone and lime-fly ash treatments. These findings highlight the importance of incorporating cementitious materials to enhance the durability and performance of lime-stabilized soils under harsh environmental conditions.
