Expansive clay

<p>Expansive clay, also called expansive soil, is a <a href="/facts/Clay/xnwouEkB">clay</a> <a href="/facts/Soil/5Ddpr3QM">soil</a> prone to large volume changes (swelling and shrinking) directly related to changes in <a href="/facts/Water_content/N0MlAYmb">water content</a>. Soils with a high content of expansive minerals can form deep cracks in drier seasons or years; such soils are called <a href="/facts/Vertisol/aRQTrfrs">vertisols</a>. Soils with <a href="/facts/Smectite/A1Sod7Hp">smectite</a> <a href="/facts/Clay_minerals/A1Sod7Hp">clay minerals</a>, including <a href="/facts/Montmorillonite/PxKtefgA">montmorillonite</a>, kaolinite, <a href="/facts/Bentonite/N9Hb8lX9">bentonite</a>, and illite group minerals, have the most dramatic <a href="/facts/Shrink%E2%80%93swell_capacity/PVRfoewX">shrink-swell capacity</a>.
</p><p>The mineral make-up of this type of soil is responsible for the moisture retaining capabilities. All clays consist of mineral sheets packaged into layers, and can be classified as either 1:1 or 2:1. These ratios refer to the proportion of tetrahedral sheets to octahedral sheets. Octahedral sheets are sandwiched between two tetrahedral sheets in 2:1 clays, while 1:1 clays have sheets in matched pairs. Expansive clays have an expanding crystal lattice in a 2:1 ratio; however, there are 2:1 non-expansive clays.
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Expansive clay open-in-new

Expansive clay