A Comparative Study on the Performance of Freeze-Thaw Cycled Alluvial Soils Stabilized with Lime and Fly Ash

This paper presents a comparison of the stabilization of alluvial soils using lime and fly ash. It aims to draw basic inferences for these soils based on the test results obtained. In this regard, lime and fly ash were added to silty alluvial soil at different rates, and the s1amples were subjected to different curing periods. The cured samples underwent 0 and 1 freeze-thaw cycles in a closed-system cabinet by maintaining the specimens at -24°C and +24°C for 24 hours each, to evaluate the influence of temperature changes. Based on the undrained shear strength values obtained from the unconsolidated-undrained triaxial tests, the most prominent finding is that stabilization with fly ash performed better than with lime, as the alluvial soil was rich in silts. The optimal stabilization period was determined as 28 days for both stabilizers. The increased curing time was influenced by mechanisms potentially arising from the use of calcium-based stabilizers in a sulfate-containing environment, which was most evident in lime stabilization. While the most effective lime stabilization was achieved between 3% and 6%, this range increased to as much as 20% for fly ash. Although fly ash stabilization yielded better results in terms of undrained shear strength, lime stabilization demonstrated better performance against freeze-thaw cycles.