Sieve analysis deals with the method for the determination of grain size distribution in soils. An analysis of this kind express quantitatively the
proportions by mass of the various sizes of particles present in the soil. In a soil, the gravel, sand, silt and clay fractions are recognize as containing particles
of decreasing magnitude.
The results of grain size analysis are widely used in soil classification. The data obtained from grain size distribution curves is used in the design of filters for earth dams to determine the suitability of soils for road construction.
Apparatus
- Balunce: Sensitive to 0.1 percent of the weight of sample to be weighed.
- Sieves: 20 mm IS Sieve, 10 mm IS Sieve, 4.75 mm IS Sieve, 2.00 mm IS Sieve, 1.18 mm IS Sieve, 600 μm IS Sieve, 425 μm IS Sieve, 300 μm IS Sieve, 212 mm IS Sieve, 150 μm IS Sieve, 75 μm IS Sieve, Pan conforming to the requirement
- Rubber Pestle and Mot-tat
Preparation of Sample
- The portion of the soil passing 4.75-mm IS Sieve obtained as given in shall be oven-dried at 105 to 110°C.
The oven-dried material shall then be riffled so that a fraction of convenient mass is obtained.
This shall be about 200 g if a substantial proportion of the material only, just passes the 4.75-mm IS Sieve or less if the largest size is smaller.
The fraction shall be weighed to 0. 1 percent of its total mass and the mass recorded.
The riffled and weighed fraction shall be spread out in the large tray or bucket and covered with water.
- Two grams of sodium hexametaphosphate or one gram of sodium hydroxide and one gram of sodium carbonate per liter of water used should then be added to the soil. The mix should be thoroughly stirred
and left for soaking.
Procedure
- The soil soaked specimen should be washed thoroughly over the nest of sieves, nested in order of their fineness with the finest sieve (75-micron IS Sieve) at the bottom. Washing shall be continued until the
water passing each sieve is substantially clean. Care shall be taken to see that the sieves are not overloaded in the process.
- The fraction retained on each sieve should be emptied carefully without any loss of material in separate trays. Oven dried at 105 to 110°C and each fraction weighed separately and the masses recorded.
- Alternatively, the soaked soil specimen may be washed on the 75-micron IS Sieve until the water passing the sieve is substantially clean.
The fraction retained on the sieve should be tipped without loss of material in a tray, dried in the oven and sieved through the nest of sieves, either by hand or by using mechanical
sieve shaker. The fraction retained on each sieve should be weighed separately and the masses recorded.
- The portion of the soil sample retained on 4.75-mm IS Sieve, selected as given in Preparation of Sample;shall be weighed and the mass recorded as the mass of the sample uncorrected for hygroscopic moisture.
- The quantity of the soil sample taken shall depend on the maximum particle size contained in the soil (see Note I).
- The sample shall be separated into various fractions by sieving through the Indian Standard Sieves see Appratus other sieves may be introduced between the sieves mentioned depending upon the additional information that may be desired to be obtained from the analysis.
- While sieving through each sieve, the sieve shall be agitated so that the sample rolls in irregular motion over the sieve.
- Any particle may be tested to see if they will fall through but they shall not be pushed through.
- The material from the sieve maybe rubbed, if necessary, with the rubber pestle in the mortar taking care to see that individual soil particles are not broken and re-sieved to make sure that only individual particles are retained.
- The quantity taken each time for sieving on each sieve shall be such that the maximum weight of material retained on each sieve at the completion of sieving does not exceed the values given in Note 2.
Note 1
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 follows:
The mass of soil sample taken for analysis
Sr. |
Maximum Size of material Present in Substantial Quantities (mm) |
Mass to be taken for Test (kg) |
1. |
75 |
60 |
2. |
40 |
25 |
3. |
25 |
13 |
4. |
19 |
6.5 |
5. |
12.5 |
3.5 |
6. |
10 |
1.5 |
7. |
6.5 |
0.75 |
8. |
4.75 |
0.4 |
Note 2
Maximum weight of material to be retained on each sieve at the completion of sieving shall be as follows:
Maximum weight of material to be retained oneach sieve
Sr. |
IS sieve Designation |
450 mm Dia Sieves (kg) |
300 mm Dia Sieves (kg) |
1. |
80 mm |
15 |
6 |
2. |
20 mm |
4 |
2 |
3. |
4.75 mm |
1.0 |
0.5 |