Frost heaving

Frost heave (including frost heave ) refers to the raising of the ground by ice formation at ground frost in a frost-susceptible soil. The approximately nine percent increase in volume of freezing water is not, as is often wrongly believed the ultimate cause. The decisive factor for frost heave is rather that is displaced by thermodynamic processes in conjunction with capillary effects, the pore water of the soil toward the freezing front - ie generally upward - and collects in deep-frozen state, usually in the form of ice lenses or Kammeis. That is not the increase in volume of freezing water for this effect is crucial, has been demonstrated by Stephen Taber (1882-1963), Director of the Geological Institute of the University of South Carolina. He devoted himself since the late 1920s this phenomenon and demonstrated that frost heave occurs in a soaked with benzene soil, ie by a substance whose volume decreases during freezing.

If the freezing front does not propagate parallel to the ground surface, this effect can also act laterally, then being spoken of frost thrust. In the soil with frost heave ice forming which exceeds the pore volume is referred to as Segregationseis. Repeated freezing and thawing frost heave can cause greater located objects in the ground, so for example stones, are transported to the soil surface. This effect is called freezing-.

Frost heave is favored by a high water table, a low applied load, a slow rate of freezing and frost susceptibility of the soil. Frost -prone soils are typically fine-pored and have a high permeability.