Fat vs Lean Clay

[pdsb5uc]

How do I recognize a fat clay vs a lean clay in the field (while logging the boreholes) without doing any LL tests on it? Also, any tips to distinguish clay from silt?

 

[bb29510]

fat clay will stick to your shoes, silty clay will have a little grit when rub between your finger. I know it sounds like I,m joking but think about it.

 

[TAC]

A lot of times fat clay will have a shiny and smooth apppearance when you rub it with your thumb. Lean clays will tend to be duller and grittier.

 

[pdsb5uc]

Thanks for your feedback, brownbag and TAC. That is the kind of information I was looking for.

 

[sc]

The US Army corps of Engineers has a site for geotechnical investigations aimed at "low tech analysis". This site ahs a number of documents freely available, including a terrific chart on the classification of soils by hand.

Unfortunately I do not have the site address any more due to a PC upgrade. If I can find it again I will post it here.

Regards

SC