Effects of Cyclic Freeze and Thaw on Engineering Properties of Compacted Loess and Lime-Stabilized Loess

Abstract

Loess is a problematic soil, which is often characterized with loose structure and high potential for collapse by water or external loads. In cold regions, the challenge of loess is further compounded by the seasonally frozen weather as the cyclic freeze-thaw action can disrupt the structure of natural loess, resulting in increased compressibility and decreased strength of the loess. A common practice to improve loess properties is to compact loess or chemically stabilize loess using cement, lime, or other binders. Although extensive studies have been conducted on the influence of freeze-and-thaw (F-T) cycles on engineering properties of soils, limited work has been done on freeze-thaw effects on loess and even less work has been concerned about lime-stabilized loess affected by cyclic freeze and thaw. This paper aims to fill such a research gap by performing a comprehensive laboratory study in a closed system to evaluate the impact of cyclic freeze and thaw on engineering properties of compacted loess and lime-stabilized loess, including changes in volume, moisture content, Atterberg limits, stress-strain relationships, modulus, and strength. The test results show that freeze-thaw cycles resulted in increase in soil volume, decrease in moisture content, but negligible change in Atterberg limits. The elastic modulus and peak shear strength of lime-stabilized loess were decreased to the lowest by approximately 15%–25% after three freeze-thaw cycles and the decreasing rate was more significant at a lower confining pressure. However, both the modulus and strength recovered and even exceeded the initial values after 11 F-T cycles.