ASTM Definition of Clay Size Particle

[BigH]

I have always understood that the clay size particles were those considered less than 0.002 mm. If one "googles" all the answers seem to confirm this. Yet, ASTM D422 indicates that clay size particles are less than 0.005 mm and colloidal particles are less than 0002 mm.

This is not addressed specifically in ASTM D2487 (classification. So, what is considered "clay size"?

 

[morecoffeeplz]

I believe that the older USBR classification method used the 0.005 mm as the clay demarcation. ASTM D422 is now withdrawn and ASTM D7928, the current procedure for the hydrometer test does list 0.002 mm as the clay size.

 

[dik]

Does anyone know the difference in properties between a particle size of 0.002mm and 0.005mm? I understand that most clays are feldspatic material, and are platelets only a few molecules thick.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[geotechguy1]

Dik,

It's mostly about mineralogy I believe - whether the clay fraction is kaolinite / illite or contains other clay-type particles like halloysite, allophane, or montmorillonite

 

[dik]

Thanks... Do you know what the difference in properties between a particle size of 0.002mm and 0.005mm is, and what the effect is?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[BigH]

Thanks morecoffeeplz - working overseas for years, I was not familiar of the hydrometer replacement standard.

Don't drink the coffee although my sister is hooked. Ever try Luwak???

 

[morecoffeeplz]

I googled Luwak. If the defecation aspect did not turn me off, certainly the manner in which the civets are treated does!