Could anyone refer me to a publication/textbook that discusses a basic model for swell prediction in unsaturated clay soils?
The maximum capacity o swellingof a clay depends of one hand the layer charge of the phyllosilicates and onthe other hand on the nature ofthe cations. There is many reference where this study has been done see as an example J. Chem. Phys., Vol. 115, No. 7, 15 August 2001 and American Mineralogist, Volume 90, pages 166172, 2005
First differentiate saturated and unsaturated clays - then the swelling and cation exchion capacity depends on the surface area, nature of the clay (ordered or disordered shape) and the nature of ions which it can sorb or not - go to google scholar and download hundreds of publications.
The amount of swell of clay soils is dependent on the type of clay.
Kayolinite swells very little, while Bentonite swells a lot. the Clay
Adsorbs water molecules onto the surface of the tiny "tiles" or "tablets"
of clay, as clay is deposited , or compressed into sheets.
I remember one construction job that I worked on, was hauling in claystone, and it
required 27 % water to reach optimum moisture content. It was excavated at
a moisture content of 3 %. The Claystone was overconsolidated as it previously had
more than two thousand feet of overburden up to 35 million years ago before uplift and erosion set in and removed the 2,000 feet of materials.
Do not forget that clay not only retains water in the interlamelar space but also in the interparticle voids related to the clay particle packing. This is particular true for clays which swell little. One of my French colleague published a lot in this area in the international litterature during the 90s. His name is Daniel Tessier, from the National Institute for Agronomical Research. I guess that many of his papers can be found.
George Xeidakis, University of Thrace, Greece.
To my knowledge, so far, there is no satisfactory model to predict the swelling potential/capacity of unsaturated soils, since the swelling capacity of a soil depends on many factors e.g clay mineralogy, existing cations in the clay, the cementing material and the degree of saturation of the soil, etc.. Thus the results are locality depended. There are some laboratory and field tests that can give an (approximate) result. There are also many statistical (regression) models(equations) in various papers and books. You can find many of them in a literature search through the Google and elsewhere.
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