Why does frost action damage roads and buildings in cold regions?

Frost action damages infrastructure in cold regions through the cyclic freezing and thawing of moisture within the ground. This process creates two primary mechanical threats to roads and buildings:1

• Frost Heaving: During winter, the freezing of ground moisture causes an upward displacement of the soil, which can physically lift and crack foundations or pavement.12
• Loss of Bearing Strength: In the summer, the excess moisture that accumulated during the freezing process remains in the ground as it thaws. This creates a saturated, unstable layer with significantly reduced bearing strength, leading to the subsidence or structural failure of roads and buildings.13

These issues are particularly severe in areas with fine-grained sediments, such as silt or silty clay, and are often exacerbated by the presence of permafrost, which prevents proper drainage. To mitigate this, engineers often use thick gravel pads to restrict seasonal freezing and thawing to the fill material itself, thereby protecting the underlying ground from these destabilizing cycles.1