FM of sand 6

[Geokhan]

Hlo everybody....why we not sum the retain of mesh#200 while performing FM of sand??

 

[BigH]

Because that is not the definition of the Fineness Modulus? Why do we do Atterbergs on -0.425 and not only on the -0.070?

 

[Ron]

BigH is right as always! The fineness modulus has two primary functions: first is a parameter that helps in concrete mix designs (finer sands create both higher water demand and higher cement demand as the specific surface of finer materials is greater...that's why we like to set the lower limit of fineness modulus for fine aggregate to be in the 2.5 range...higher is better within reason) and the second is that of capillary rise in soils where the vertical rise of moisture needs to be controlled. In that case, you would want a fineness modulus at about 3.0 or above.

 

[Geokhan]

Nice explaination...but #200 sieve retains are fine sand size not clay or silt...

 

[geotechguy1]

To carry on with BigH's post: Why are #200 sieve retains fine sand size?

Because someone defined them as fine sand size and the industry adopted the standard

 

[dik]

I understand that anything finer than #200 is silt or clay, and not sand at all... different category. Sorry... Geok answered this already...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik