Resilient Properties of Unbound Road Materials during Seasonal Frost Conditions

TLDR

Research has focused on the resilient properties of unbound road materials, yet the impact of cold‑region climates on these properties remains underexplored. The paper develops equations to predict resilient modulus under varying freeze‑thaw conditions. Coarse and fine‑grained subgrade soils were tested in a triaxial cell from room temperature to −10 °C and back, eliminating handling disturbances. Freeze‑thaw cycling markedly reduced resilient modulus in all soils, produced pronounced hysteresis in clay, and the resulting equations can inform resilient modulus selection in design.

Abstract

During recent decades, a considerable amount of research has been devoted to the resilient properties of unbound road materials. However, the severe effects of cold region climates on resilient behavior have been less exhaustibly investigated. In this study, the results from extensive resilient modulus laboratory tests during full freeze-thaw cycling are presented. Various coarse and fine-grained subgrade soils were tested at selected temperatures from room temperature down to −10°C and back to room temperature. The soils are frozen and thawed inside a triaxial cell, thus eliminating external disturbances due to handling. The results indicate that all the soils exhibited a substantially reduced resilient modulus after the freeze-thaw cycle. A significant hysteresis for the clay soil in warming and cooling was also observed. This paper presents equations for different conditions. The equations may be used for selecting the appropriate resilient modulus value in current and future evaluation and design methods.