Constitutive Modeling of Cement-Based Foamed Lightweight Soil under Freeze-Thaw-Induced Stiffness and Strength Degradation

Foamed lightweight soil (FLS) demonstrates exceptional thermal insulation and mechanical properties, making it as a highly promising material for subgrade construction in seasonally frozen regions. Its application aims to alleviate deformation and structural damage caused by freeze-thaw cycles, thereby significantly enhancing the durability of subgrades. This study aims to comprehensively elucidate the mechanical properties and stress-strain behavior of cement-based FLS when subjected to repeated freeze-thaw cycles through unconfined compressive strength (UCS) tests and stress-strain analysis. Experimental findings indicate that the UCS of FLS exhibits a consistent decline as the number of freeze-thaw cycles increases. Moreover, the resistance of FLS specimens to freeze-thaw cycle degradation decreases with higher clay content, while it is significantly enhanced with an increase in wet density. To analyze the stress-strain relationships in greater detail, a hyperbolic model was adopted for normalization and applied to specimens exposed to varying freeze-thaw cycles and differing clay contents. This methodology enabled the accurate prediction of stress-strain curves, with the predicted values showing a high correlation with experimentally measured data, thus validating the predictive model' s high accuracy. These results highlight the potential of cement-based FLS as a durable and adaptive material for road infrastructure in cold climates, providing critical insights into its performance deterioration under cyclic freezing and thawing conditions. This research establishes a reliable predictive framework for assessing the mechanical behavior of cement-based FLS, offering valuable guidance for its practical implementation to improve the long-term stability and resilience of subgrades in seasonally frozen regions.