Freezethaw

Freezethaw, also known as freeze-thaw cycling, is a weathering process driven by the freezing and thawing of water within pores, cracks, and voids of rocks, soils, and man-made materials. When water freezes, it expands by about 9% in volume, generating tensile stresses that can exceed the strength of the surrounding material, leading to cracking, spalling, and progressive deterioration. These cycles occur in climates where temperatures repeatedly fall below and rise above the freezing point.

In geology and geomorphology, freeze-thaw contributes to frost action. Water migrates to freezing fronts in soils, freezes expanding and pushing grains apart; repeated events cause frost heave, ground deformation, and rock breakage via frost wedging. In mountainous or periglacial environments, this drives rock fragmentation and soil movement; in pavements, it causes damage at joints and edges.

In construction, freeze-thaw durability is a key factor for concrete, masonry, and asphalt. Problems arise when materials are saturated with water or have high porosity and low air voids. Repeated cycles produce microcracking, scaling, and loss of strength. Mitigation includes controlling water ingress, improving drainage, using air-entraining admixtures in concrete, selecting frost-resistant aggregates, and avoiding or limiting de-icing salts, or using sealants. Materials testing, such as accelerated freeze-thaw cycling tests, assesses durability.

Climate change and urban environments can intensify freeze-thaw effects by altering moisture availability and salt use. Understanding freezethaw is important for engineering design, maintenance, and geotechnical assessment. Related topics include frost wedging and frost heave.