19-04-2014, 01:02 PM
DETERMINATION OF SPECIFIC GRAVITY OF SOIL SOLIDS
AIM
To determine the specific gravity of soil solids.
THEORY AND APPLICATION
Specific gravity of soil solids is the ratio of weight, in air of a given volume; of dry soil solids to the
weight of equal volume of water at 4oC.Specific gravity of soil grains gives the property of the
formation of soil mass and is independent of particle size. Specific gravity of soil grains is used in
calculating void ratio, porosity and degree of saturation, by knowing moisture content and density.
The value of specific gravity helps in identifying and classifying the soil type.
APPARATUS
1. Pycnometer
2. 450 mm sieve
3. Weighing balance
4. Oven
5. Glass rod
6. Distilled water
PROCEDURE
1. Dry the pycnometer and weigh it with its cap. (W 1)
2. Take about 200gmof oven dried soil passing through 4.75mm sieve into the pycnometer and
weigh again (W 2).
3. Add sufficient de-aired water to cover the soil and screw on the cap.
4. Shake the pycnometer well and remove entrapped air if any.
5. After the air has been removed, fill the pycnometer with water completely.
6. Thoroughly dry the pycnometer from out side and weigh it (W 3).
7. Clean the pycnometer by washing thoroughly.
8. Fill the cleaned pycnometer completely with water up to its top with cap screw on.
9. Weigh the pycnometer after drying it on the outside thoroughly (W 4).
10. Repeat the procedure for three samples and obtain the average value of specific gravity.