Editing Adobe (section)

==Composition==
[[File:Santa Fe adobe.jpg|thumb|Adobe style in [[Santa Fe, New Mexico]]]]
An adobe brick is a [[composite material]] made of earth mixed with water and an organic material such as [[straw]] or [[Dung (matter)|dung]]. The [[soil]] composition typically contains [[sand]], [[silt]] and [[clay]]. Straw is useful in binding the brick together and allowing the brick to dry evenly, thereby preventing cracking due to uneven shrinkage rates through the brick.<ref>{{cite journal|last=Vargas|first=J.|author2=J. Bariola|author3= M. Blondet|title=Seismic Strength of Adobe Masonry|journal=Materials and Structures|year=1986|volume=9|issue=4|pages=253–256|doi=10.1007/BF02472107|s2cid=108826268}}</ref> Dung offers the same advantage. The most desirable soil texture for producing the mud of adobe is 15% clay, 10–30% silt, and 55–75% fine sand.<ref>{{cite web|last=Garrison|first=James|title=Adobe-The Material, Its Deterioration, Its Coatings|url=http://missions.arizona.edu/sites/default/files/1%20Garrison-Adobe%20Characteristics.pdf|access-date=27 February 2013|pages=5–16|archive-date=5 March 2016|archive-url=https://web.archive.org/web/20160305165712/http://missions.arizona.edu/sites/default/files/1%20Garrison-Adobe%20Characteristics.pdf|url-status=dead}}</ref> Another source quotes 15–25% clay and the remainder sand and coarser particles up to cobbles {{convert|2|to|10|in|mm|order=flip|-1|abbr=on}}, with no deleterious effect. Modern adobe is stabilized with either emulsified asphalt or Portland cement up to 10% by weight.

No more than half the clay content should be [[expansive clay]]s, with the remainder non-expansive illite or kaolinite. Too much expansive clay results in uneven drying through the brick, resulting in cracking, while too much kaolinite will make a weak brick. Typically the soils of the Southwest United States, where such construction has been widely used, are an adequate composition.<ref>{{cite web|last=Austin |first=George |url=http://geoinfo.nmt.edu/publications/periodicals/nmg/downloads/6/n4/nmg_v6_n4_p69.pdf |work=New Mexico Geology, November 1984 |publisher=New Mexico Bureau of Mines and Mineral Resources |title=Adobe as a building material |url-status=dead |access-date=27 February 2013 |page=70 |archive-url=https://web.archive.org/web/20131202232337/http://geoinfo.nmt.edu/publications/periodicals/nmg/downloads/6/n4/nmg_v6_n4_p69.pdf |archive-date=2 December 2013 }}</ref>