Swelling strain interpretation

[bublik]

Dear all,

I got different swelling test results and don't know how to decode them. I searched for the information but found nothing That is why I need your help.
Does anyone know what 20% of swelling strain mean? I need something like table with certain criteria, like: 0-5% of swelling is very low, 5-10 is low, 10-15 is meduim and etc.

Thanks in advance.

 

[Ron]

What is the context of the swell potential? Is this for soil under a foundation or a pavement? How was the testing done?

 

[nagatalluri]

20% swelling strain could mean volumetric swell (swell in vertical and radial directions combined).There is no specific criteria but less than 10% volumetric swell can be considered as non-problematic and this classification is project specific.

 

[bublik]

Ron,

Swelling test was done on samples from the existing working so there are some small shallow foundations. Swelling (and other) tests were done to find the reason for soil settlement under some foundations. Test was done according to BS standard (1377).

nagatalluri,

20% of swell is vertical, i.e. 20% of the initial height of sample (which was 20mm).
The problem is I could not find any criteria for that, but I can't tell this to client as he needs to hear something specific. What do you mean when saying "this classification is project specific"?

 

[nagatalluri]

Ron,

In pavement geotechnics especially in subgrade soils, we talk about volumetric swell (swell in all directions). When the soil is expansive lets say the volumetrc swell is above 10%, lime or cement treatment is recommended. Lime/cement treatment reduces the swell and improves the workability of soils. Though swell may not reduce to Zero, transportation agencies depending on the type of road (low volume or highway)specify the acceptable swell. This what I mean "project specific"

 

[TexasGeotech]

20% vertical strain (vertical swell) is an indication of the clay mineralogy and shrink-swell behavior. That sounds like nasty clay, design with caution.