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Soil is placed into the metal cup (Casagrande cup) portion of the device and a groove is made down at its center with a standardized tool of 2 millimetres (0.079 in) width. The cup is repeatedly dropped 10 mm onto a hard rubber base at a rate of 120 blows per minute, during which the groove closes up gradually as a result of the impact.
A COLE value of 0.06 means that 100 inches of soil will expand by 6 inches when wet. [2] Soils with this shrink-swell capacity fall under the soil order of Vertisols . [ 6 ] As these soils dry, deep cracks can form on the surface, which then allows water to penetrate to deeper levels of the soil. [ 7 ]
Clay is a type of fine-grained natural soil material containing clay minerals [1] (hydrous aluminium phyllosilicates, e.g. kaolinite, Al 2 Si 2 O 5 4). Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impurities, such as a reddish or brownish colour from small amounts of iron oxide .
For example, a sandy loam soil with 20% gravel would be called gravelly sandy loam. When the organic component of a soil is substantial, the soil is called organic soil rather than mineral soil. A soil is called organic if: Mineral fraction is 0% clay and organic matter is 20% or more
The Unified Soil Classification System (USCS) is a soil classification system used in engineering and geology to describe the texture and grain size of a soil. The classification system can be applied to most unconsolidated materials, and is represented by a two-letter symbol. Each letter is described below (with the exception of Pt):
Bentonite layers from an ancient deposit of weathered volcanic ash tuff in Wyoming Gray shale and bentonites (Benton Shale; Colorado Springs, Colorado). Bentonite (/ ˈ b ɛ n t ə n aɪ t / BEN-tə-nyte) [1] [2] is an absorbent swelling clay consisting mostly of montmorillonite (a type of smectite) which can either be Na-montmorillonite or Ca-montmorillonite.
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Water is pulled by capillary action due to the adhesion force of water to the soil solids, producing a suction gradient from wet towards drier soil [50] and from macropores to micropores. [51] The so-called Richards equation allows calculation of the time rate of change of moisture content in soils due to the movement of water in unsaturated ...