How to Use 0.002mm. as the Grain Size Silt/Clay Division
Several users have inquired as to how to set up their grain size test
so that it uses 0.002mm. as the breakpoint between silt and clay particle
sizes. There's two options for doing this; the "best"
option is subject to engineering judgement and the requirements of
the test you performed!
- If you're classifying the soil via AASHTO or USDA classification methods,
select either "AASHTO" or "USDA" as your grain size
test's "Classification system" (select "Window"
> "Sample Info." from the menu at the top of the screen,
then look for the "Classification system" box towards the
bottom of the screen).
- If you're sure that you want to use the divisions specified by the USCS
classification system (e.g., gravel is between 3/4" and 3", sand
between the #200 and the #4 sieve, etc.), but you want the silt/clay division
to be 0.002mm. instead of 0.005mm.: Open your grain size test, select
"Window" > "Sample Info." from the menu at
the top of the screen, then select "USCS with .002mm. instead
of .005 silt/clay division" as the test's "Classification
system" (look for the box towards the bottom of the screen).
