Fatigue Performance of Cemented Aeolian Sands: Linking Material Structural Characteristics to Long-Term Subgrade Durability

In arid and semi-arid regions, subgrades often consist of loose aeolian sands with insufficient bearing capacity, making effective stabilization essential. Among various techniques, soil–cement columns present a viable solution; however, their long-term performance under cyclic loading is frequently neglected in design considerations. This study investigated the fatigue behavior of cement-treated aeolian sands, representative of soil–cement column materials, subjected to uniaxial cyclic compressive loading, focusing on the effects of cement content and dry density. Cylindrical specimens were prepared with cement contents of 2%, 3%, and 4% (by dry weight) and two dry densities corresponding to relative densities of 10% and 70% in uncemented sand. Cyclic tests were conducted under sinusoidal loading with stress levels ranging from 70% to 98% of the monotonic strength. Fatigue life as well as axial strains were measured, while Scanning Electron Microscopy (SEM) was employed to examine the microstructural features. The results demonstrated that increasing both cement content and density significantly enhances fatigue life. Microstructural analyses revealed that, beyond the quantity of bonds, the spatial distribution and morphology of interparticle bonds critically influence fatigue resistance. Additionally, the evolution and accumulation of dissipated energy were found to be closely associated with fatigue life and applied stress levels. A predictive model was proposed based on total cumulative dissipated energy and the porosity/cement index, providing a practical tool for assessing the durability of stabilized sands. These findings contribute to a deeper understanding of fatigue mechanisms in cemented aeolian sands and support the design of more resilient subgrades in dry regions.