Editing Soil classification (section)

=== Engineering ===
[[Geotechnical engineering|Geotechnical engineers]] classify soils according to their engineering properties as they relate to use for foundation support or building material. Modern engineering classification systems are designed to allow an easy transition from field observations to basic predictions of soil engineering properties and behaviors. 

The most common engineering classification system for soils in North America is the [[Unified Soil Classification System]] (USCS). The USCS has three major classification groups: (1) coarse-grained soils (e.g. [[Sand|sands]] and [[Gravel|gravels]]); (2) fine-grained soils (e.g. [[Silt|silts]] and [[Clay|clays]]); and (3) highly organic soils (referred to as "[[peat]]"). The USCS further subdivides the three major soil classes for clarification. It distinguishes sands from gravels by grain size, classifying some as "well-graded" and the rest as "poorly-graded". Silts and clays are distinguished by the soils' [[Atterberg limits]], and thus the soils are separated into "high-plasticity" and "low-plasticity" soils. Moderately organic soils are considered subdivisions of silts and clays and are distinguished from inorganic soils by changes in their plasticity properties (and Atterberg limits) on drying. The European soil classification system (ISO 14688) is very similar, differing primarily in coding and in adding an "intermediate-plasticity" classification for silts and clays, and in minor details.

Other engineering soil classification systems in the United States include the [[AASHTO Soil Classification System]], which classifies soils and aggregates relative to their suitability for pavement construction, and the Modified [[Donald Burmister|Burmister]] system, which works similarly to the USCS but includes more coding for various soil properties.<ref>{{cite web |url=http://www.civil.columbia.edu/ling/burmister/burmister.html |title=Donald M. Burmister |publisher=Civil.columbia.edu |access-date=2014-06-11 |archive-url=https://web.archive.org/web/20120415003511/http://www.civil.columbia.edu/ling/burmister/burmister.html |archive-date=2012-04-15 |url-status=live }}</ref>

A full geotechnical engineering soil description will also include other properties of the soil including color, in-situ moisture content, in-situ strength, and somewhat more detail about the material properties of the soil than is provided by the USCS code. The USCS and additional engineering description is standardized in ASTM D 2487.<ref>{{Citation |publisher=American Society for Testing and Materials |year=1985 |series=D 2487-83 |title=Classification of Soils for Engineering Purposes: Annual Book of ASTM Standards |volume=04 |issue=8 |pages=395–408 |url=http://www.astm.org/Standards/D2487.htm |access-date=2015-05-08 |archive-url=https://web.archive.org/web/20100914111626/http://www.astm.org/Standards/D2487.htm |archive-date=2010-09-14 |url-status=live }}</ref>