I know the exchangeable cations affect on the diffuse double layer thickness and also help the soil particle to aggregate and flocculate altogether. Is there any other correlation between the exchangeable cations and the strength of the soil?
Dear Professor Towe,
I mean the effect of cations in the diffuse double layer (around the surface and also broken edges). Does the exchange of these cations has any effect on the soil properties (compacted and loose soil)?
Thank you for your time.
Kind regards,
Ebrahim Sangsefidi
Dear Professor Towe,
The soil composition that is usually used in pavement construction is 50% gravel, 40% sand, 10% silt and clay. However, a great attention is paid not not use plastic fine material, based on the chemical weathering during wetting and drying process some plastic fine material may produce and also the amount of fine particles may increase.
I hope this comment give you a hint, even though, the effect of exchangeable cations on the properties of any kind soil that you may have in your mind may give me hint and help me to find my way (some references in this area can help me significantly).
Thanks again for your time.
Kind regards,
Ebrahim
I am not much aware of the civil engineering interpretation of soil materials and properties.But I can comment on some general properties of soils when saturated with different dominant cations on soil cation exchange sites.In soils having pH less than 6 (predominantly below 5.5) Al3+and H+ ions dominate,as pH increases from 6.5 to 8.5( 8.2),the proportion of Ca on exchange complex increases(60 to 80 or more per cent) and above pH 8.5(8.3) the exchangeable Na proportion may increase to 15%or more.When calcium is dominant ion the soil clay will be in flocculated state and soil will have good aggregation and structure.If Na is dominant on exchange complex,the clay will be deflocculated,disperse and poor structure and aggregation.The clay will be wet,hydrated and slide under pressure.Mg also may behave similar to Na if it is in high amount on exchange complex.I read a novel ,long time ago. where a bridge slides over a wet Na saturated montmorillonitic clay soil. Al3+ on hydrolysis generates more protons and deteriorates the soil mineral structures.
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