Frost can damage pavements and building structures in two ways: heaving of the frozen ground, caused by ice lenses forming in the soil, and collapse of the ground, caused by the thaw of these same ice lenses. The amount of frost heave can be tremendous. In one case, a seven-story building heaved 2 to 3 inches. Vertical ground movements of 4 to 8 inches are common and as much as 24 inches have been reported. Variations in the amount of heave, due to different soil and water conditions, can crack structures easily. Walls, slabs, footings, and pavements all can be damaged.
THREE CONDITIONS REQUIRED FOR FROST HEAVE
For frost heave to occur, three things must be present: freezing temperatures, water, and frost-susceptible soil.
THREE WAYS OF PREVENTING FROST HEAVE
Because of heat loss to the surrounding soil, heated buildings rarely suffer frost heave damage. Frost heave also is avoided by extending footings below the frost line. Pavements, driveways, sidewalks, and floor slabs of unheated buildings are not supported by footings, however. To protect these structures, you must eliminate or minimize at least one of the three conditions that lead to frost heave: reduce frost penetration; keep water out of the freezing zone; or make sure soil in the freezing zone is not susceptible to frost.