test determines the relative proportions of different soils 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:
Stack of Sieves including pan and cover
Balance (with accuracy to 0.01 g)
Rubber pestle and Mortar ( for crushing the soil if lumped or conglomerated)
Mechanical sieve shaker
Oven
Notice: The balance to be used should be sensitive to the extent of 0.1% of total weight of sample taken.
Test Procedure:
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)
If soil particles are lumped or conglomerated crush the lumped and not the particles using the pestle and mortar.
Determine the mass of sample accurately. Wt (g)
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)