Shrink–swell capacity

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The shrink–swell capacity of clay refers to the extent to which a clay will expand when wet and retract when dry. Soil that is problematic due to high capacity is known as shrink–swell soil, or expansive soil.


Due to the physical and chemical properties of some clays[1] (such as the Lias Group) large swelling occurs when water is absorbed. Conversely when the water dries up these clays contract (shrink).


Clay groups with a high shrink–swell capacity tend to damage crops during dry spells, as the soil contracts, pulling roots apart.[1] Additionally in wet periods expansion of the clay can lead to ground heave, which can damage the foundations of buildings.[2]


  1. ^ a b Nagel, David. "Soil Science for Vegetable Producers." MSU: Coordinated Access to the Research and Extension System. 2001. Mississippi State U. 6 July 2008
  2. ^ British Geological Survey