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.

Description[edit]

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).

Problems[edit]

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]

References[edit]

  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 http://msucares.com/pubs/publications/p1977.htm.
  2. ^ British Geological Survey http://www.bgs.ac.uk/science/landUseAndDevelopment/shallow_geohazards/shrinking_and_swelling_clays.html