Silty-Clay Visual Classification
Silty-Clay Visual Classification
(OP)
Can a soil be classified Silty lean Clay(CL) by visual observation in the field. One of my friend argues that this must be only lab determined and not in the field. Is this acceptable by ASTM standard? or should this be classified as Silt and Clay.





RE: Silty-Clay Visual Classification
RE: Silty-Clay Visual Classification
RE: Silty-Clay Visual Classification
RE: Silty-Clay Visual Classification
RE: Silty-Clay Visual Classification
All this is contingent on using ASTM D-2487/2488 classifications
¡papá gordo ain't no madre flaca!
RE: Silty-Clay Visual Classification
RE: Silty-Clay Visual Classification
I hate this mixed classification nonsense. If you want to classify on the basis of percent silt and percent clay, use the USDA triangle and grow crops (sorry to be so blunt). It just annoys me that countless geotechnical firms choose their own methods for soil classification and then harp on ASTM standards for all sorts of other tests.
Here's where the body's burried. If you take a can of baby powder, the USDA (i.e., via hydrometer testing) would likely classify it as "clay", but the ASTM would classify it as silt. If you add 10 percent bentonite, the USDA would be unaffected, but the ASTM would (likely) call it fat clay. If you add 20 percent bentonite, the modified Bermeister would call it silty clay??????? even though the USC (i.e., via Atterberg limits) would remain CH.
Who cares? If it BEHAVES as a fat clay, call it a fat clay!! The ASTM recognizes this and assignes soil descriptions based on behavior NOT grain size. That's the way it should be - need I say IMHO?
f-d
¡papá gordo ain't no madre flaca!
RE: Silty-Clay Visual Classification
RE: Silty-Clay Visual Classification
1. Field observation --- "It's a Clay"
2. Lab testing follows --- "ok, so it's a Silt."
my gut reaction is assume all "field observed clays" are silts unless they are fat clays until proven otherwise. i agree with your friend. but, maybe you work somewhere where there are a tremendous amount of CLs out there.