Sieve Analysis Test

 

Testing objectives:
The Standard grain
size analysis test determines the relative proportions of different grain sizes as they are distributed among certain size ranges.

 

Need and Scope:
The grain size analysis is widely used in classification of soils. The data obtained from grain size distribution curves is used in the design of filters for earth dams and to determine suitability of soil for road construction, air field etc. Information obtained from grain size analysis can be used to predict soil water movement although permeability tests are more generally used.

 

Apparatus Required:

Notice: The balance to be used should be sensitive to the extent of 0.1% of total weight of sample taken.

 

Test  Procedure:

  1. take a representative oven dried sample of soil that weighs about 500 g. ( this is normally used for soil samples the greatest particle size of which is 4.75 mm)
  2. If soil particles are lumped or conglomerated crush the lumped and not the particles using the pestle and mortar.
  3. Determine  the mass of sample accurately. Wt (g)
  4. Prepare a stack of sieves. sieves having larger opening sizes (i.e lower numbers) are placed above the ones having smaller opening sizes (i.e higher numbers). The very last sieve is #200 and a pan is placed under it to collect the portion of soil passing #200 sieve.  Here is a full set of sieves. (#s 4 and 200 should always be included)
  5. Make sure sieves are clean, if many soil particles are stuck in the openings try to poke them out using brush.
  6. Weigh all sieves and the pan separately. (Fill in column 3)
  7. Pour the soil from step 3 into the stack of sieves from the top and place the cover,  put the stack in the sieve shaker and fix the clamps, adjust the time on 10 to 15 minutes and get the shaker going.
  8. Stop the sieve shaker and measure the mass of each sieve + retained soil. (fill in column 4)
1 2 3 4 5 6 7 8
sieve # Sieve size (mm) Mass of each sieve (mm) Mass of each sieve + retained soil Mass of soil retained-Wn (g)

Col4-Col3

 

Percentage on each sieve Rn

Col5/Wt *100

 

Cumulative percent retained S Rn % finer, 100- S Rn
4 4.75            
8 2.36            
16 1.18            
30 0.6            
40 0.425            
50 0.30            
100 0.15            
200 0.075            
Pan       S = W1=      

 

 

Calculation:

Column 5 = Column4 - Column3

Column 6 = Column5 / (Total mass in step 3)

Calculate the cumulative percent of soil retained on the nth sieve,

                                                            = S Rn

Calculate the cumulative percent passing through the nth sieve,

= Percent finer = 100 - S Rn or 100 - Column 7

 

Interpretation and Reporting the Results:

Draw graph of log sieve size vs % finer. The graph is known as grading curve. Corresponding to 10%, 30% and 60% finer, obtain diameters from graph these are D10, D30, D60, using these obtain Cc and Cu which further represent how well the soil is graded i.e whether the soil is well-graded, gap-graded or poorly graded.

 

A sample Calculation is given here;

 

 

 

Photos:

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A stack of sieves_Step 4