GRAIN SIZE ANALYSIS OF SOIL BY WET SIEVE ANALYSIS, IS: 2720 (Part 4): 1985

Scope: To determine grain size of soil fraction passing through 4.75 mm IS sieve and retained on 75 micron IS Sieve.

What is Grain Size Sieve Analysis (Soil Gradation) ?

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 Code For Determination of Grain Size of Soil by Wet Method :-

• IS: 2720 (Part 4): 1985

APPARATUS REQUIRED FOR THE TEST :-

• Balance weighed–sensitive to 0.1 percent of the weight of sample.
• Sieves – 4.75mm IS sieve, 2.36 mm IS sieve, 1.18 mm IS sieve, 600 micron IS Sieve, 300 micron IS sieve, 150 micron IS Sieve and 75 micron IS Sieve.
• Rubber Pestle and Mortar
• Tray
• Wire brush
• Oven–to maintain the temperature at 105ºC to 115ºC.
• Mechanical sieve shaker-(optional)
• Reagents: Sodium hexametaphosphate

4.75mm Sieve

Rubber Pestle and Mortar

Wire Brush

PROCEDURE OF THE TEST :-

1. Take sufficient quantity of 4.75 micron passing soil sample and oven dry it at temperature at 105ºC to 115ºC.
2. 100g of sample is taken and transfer it into a bowl, add water and 2g of sodium - hexametaphosphate. Soak it overnight.
3. Wash the sample on 75 micron IS sieve. Collect the retained sample and oven dry it at temperature at 105ºC to 115ºC for 24hrs.
4. 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.
5. The mass of the material retained on each sieve shall be recorded.

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

I.S Sieve Number/Size (mm)	Wt. retained in each Sieve (gm)	Percentage retained on each sieve	Cumulative percentage retained on each Sieve	% Finer
2.00
0.425
0.075
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.

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.