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2005 12 13
Expansive Soil
By Pierre Gendron


Silts and clays tend to swell and shrink with change of moisture content. They are called expansive soil. When moisture content increases, these soils exert a high upward force on foundations and floor slabs. When moisture content decreases, these soils subside allowing foundations and floor slabs to sink. Such up and down movement may cause serious structural damage.

Soils are classified by grain size and as either organic or inorganic:
-Gravel: particles over 2mm diameter
-Sands: particles from .05 to 2 mm diameter; finest grain just visible to the eye
-Silt: grains are invisible but can be felt as smooth
-Clay: under .002 mm diameter; smooth and floury when dry, plastic and sticky when wet

Some soils are unsuitable for certain uses, and layers of different soils may be useless for development as they might cause planes of slippage.


Pierre Gendron est diplomé de l'Université McGill (M.Arch II, 2003) et de l'Université de Montréal (B.Arch, 1997). Au cours des huit dernières années, il a collaboré avec les architectes George Yu et Jason King à Los Angeles et Tokyo, de même qu’avec l’Atelier Big City, à Montréal. Il est membre de Planneur (, groupe qu'il a fondé en 2004 avec Katherine Lapierre et Stephan Kowal.
[email this story] Posted by Alexandra McIntosh on 12/13 at 07:00 AM

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