Dear all,
There are some parts of the world with dispersive soils, that mostly consists of Montmorillonite clay. It is said that cause of dispersion in this clay is because of existence of Na+. However, I want to know, is there other kind of dispersive clay in your region?? what is it ?? and how you stabilized it??
Thanks
MJM
I see that in agriculture science the topic is only discussed in a particular aspect, which regards the potential collapsibility of smectitic clays under low normal stresses and high void ratios. Under the geotechnical point of view, there is much more to know (see some examples in the attachments). What you call "dispersive clay" is a clay with high specific surface and high amount of exchangeable cations, which makes it highly reactive when in contact with an aqueous solution. You call it "dispersive" because, when sufficiently diluted, it forms in fact a suspension in low concentration aqueous solutions. But, be careful, even at neutral pH, the addition of a salt such as NaCl or KCl will make the suspension flocculate, hence you understand that is not the clay itself to be "dispersive", but the behaviour depends on the whole clay+pore fluid system.
Speaking about the availability of the smectitic clays, they are actually pretty frequent, especially where you have marine sediments which formed in deep sea conditions. In Italy, our mountains are quite rich in smectitic-rich clay deposits.
Article Shear displacements induced by decrease in pore solution con...
Article A chemo-mechanical insight into the failure mechanism of fre...
Thesis Influence of pore fluid composition on clay behaviour and ch...
In Sudan we have the largest tracts of agricultural lands dominated by montmorillonitc clay (clayey soils with > 65% clay) with variable sodium content (sometimes ESP > 35%) and are considered as "dispersive soil". I think originally the clay in itself is dispersible and the presence of sodium makes physical condition even worse. I think illitic clays (silty soils) in different deposits dominated by Potassium could also be dispersive.
It should be the grade of acidity or alkalinity of the medium
Check out The Dynamics of Potassium in some Australian soils
Thesis · June 2016
DOI: 10.13140/RG.2.2.28586.00962 on this site.
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