Basic soil tests - Particle size analysis / sieve analysis

procedure

First we need to take around 500g of soil and oven dried. after that it is important to break all lumps in that soil sample.

After that we need to prepare the sieve stack. The stack of sieves is prepared with progressively increasing sieve opening and the pan is placed at the bottom. normally the stack is made so that the sieve number of the sieve is approximately twice of the sieve above it.

According to the ASTM (American Standard for Testing Materials) these are the sieve numbers and opening sizes.


Then the stack is fixed in the sieve shaker and put the soil sample to the top most sieve (to the largest opening sieve) and shake about 5 minutes.

After that complete the below table.

Example table: Sieve analysis test result

 After completion of the above chart we need to plot the ''Particle size distribution curve - PSD curve'' this is semi logarithmic graph. ( Y axis - Percentage passing, X axis - log(Sieve opening))

  Using PSD curve we can define below parameters.
1). Uniformity coefficient (Cu)
         Cu = D60/D10
2). Coefficient of gradation
         Cc = D30^2/D60xD10
From PSD curve grain size such as D10, D30, D60 can be obtained corresponding to 10%, 30%, 60% passing respectively.