GRAIN SIZE ANALYSIS OF SOIL BY DRY SIEVING METHOD, lS: 2720 (Part-4): 1985



Soil gradation (sieve analysis) is a practice or procedure used to assess the particle size distribution (also called gradation) of a granular material by allowing the material to pass through a series of sieves of progressively smaller mesh size and weighing the material retained on each sieve as a fraction of the whole mass.

For soil particles of size 4.75mm and bigger, dry sieve analysis is done and for soil particles of size above 75 micron and below 4.75mm wet sieve analysis. Wet sieve analysis is also needed if the soil particles are coated by clay/silt.

  • IS: 2720 (Part-4): 1985

APPARATUS REQUIRED FOR THE TEST :-
  • Weighing Balancesensitive to 0.1% of the weight of sample.
  • Sieves–100mm IS sieve, 75mm IS sieve, 19mm IS sieve and 4.75mm IS sieve
  • Wooden mallet
  • Tray
  • Ovento maintain the temperature at 105ºC to 115ºC.

PROCEDURE OF THE TEST :-
  1. Soil sample as received from the field shall be dried in sun. In wet weather a drying apparatus may be used in which case the temperature of the sample should not exceed 60ºC.
  2. The clods may be broken with a wooden-mallet to hasten drying. The organic matter, like tree roots and pieces of bark should be removed from the sample. Similarly, matter other than soil, like shells should also be separated from the main soil mass.
  3. When oven is used for drying, the temperature in the oven shall not exceed 110ºC.
  4. The oven dried sample is separated into 2 fractions by sieving it through a 4.75mm IS sieve. The portion retained on it is termed as gravel fraction and is kept for coarse analysis while the portion passing through it is subjected to fine sieve analysis.
  5. Depending on the maximum size of material present in substantial quantities in the soil, the mass of soil sample taken for analysis may be as given in the table.
  6. The sample shall be separated into various fractions by sieving. While sieving through each sieve the sieves shall be agitated so that the sample rolls in irregular motion over the sieves.
  7. The mass of the material retained on each sieve shall be recorded.

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Table 1: Maximum Size of Material Present in Substantial Quantities
Maximum Size of Material Present in Substantial Quantities (mm)
Mass to be Taken for Test (kg)
75
60
40
25
25
13
19
6.5
12.5
3.5
10
1.5
6.5
0.75
4.75
0.4

Table 2: Maximum Weight Retained on Sieves
IS Sieve Designation
450 mm Dia. Sieves (in kg)
300 mm Dia. Sieves (in kg)
80 mm
15 kg
6 kg
20 mm
4 kg
2 kg
4.75 mm
1.0 kg
0.5 kg


Observation and Recording

IS Sieve Number/Size (mm)
Wt. retained in each Sieve (g)

Percentage retained on each sieve
Cumulative percentage retained on each Sieve

% Finer
100
75
19
4.75
PAN


CALCULATION :-
The percentage of soil retained on each sieve shall be calculated on the basis of the total mass of soil sample taken and from these results the percentage passing through each of the sieves shall be calculated.

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REPORT :-
The results of grain size analysis shall be reported in a suitable form. A grain size distribution shall be drawn on a semi-logarithmic chart, plotting particle size on the log scale against percentage finer than the corresponding size on the ordinary scale.