Passive Subsurface Thermal Buffer Systems for Freeze–Thaw Infrastructure Protection

Freeze–thaw cycles represent one of the primary mechanisms of degradation in civil infrastructure across temperate and cold climates. Repeated crossings of the water phase boundary induce volumetric expansion within porous materials, generating microfractures that accumulate over time and lead to structural failure in pavement, foundations, and bridge decks. This disclosure describes a passive subsurface thermal buffering system designed to reduce the frequency and severity of freeze–thaw cycles in infrastructure materials. The system incorporates phase-change materials embedded within structural or subsurface layers to damp temperature oscillations near the water phase boundary. By absorbing and releasing latent heat during thermal transitions, the system suppresses rapid temperature fluctuations and reduces the number of freeze–thaw crossings experienced by the surrounding infrastructure. The architecture can be implemented in roadbeds, sidewalks, bridge decks, rail beds, airport runways, and other built environments exposed to seasonal freezing conditions. The approach offers a passive, low-energy strategy for extending infrastructure service life and reducing maintenance costs.