DETERMINATION OF SPECIFIC GRAVITY

 

OBJECTIVE
Determine the specific gravity of soil fraction passing 4.75 mm I.S sieve by density bottle.

NEED AND SCOPE

The knowledge of specific gravity is needed in calculation of soil properties like void ratio, degree of saturation etc.

DEFINITION

Specific gravity G is defined as the ratio of the weight of an equal volume of distilled water at that temperature both weights taken in air.

 

APPARATUS REQUIRED

1. Density bottle of 50 ml with stopper having capillary hole.
2. Balance to weigh the materials (accuracy 10gm).
3. Wash bottle with distilled water.
4. Alcohol and ether.

           

PROCEDURE

1. Clean and dry the density bottle  

  1. Wash the bottle with water and allow it to drain.
  2. Wash it with alcohol and drain it to remove water.
  3. Wash it with ether, to remove alcohol and drain ether.

2. Weigh the empty bottle with stopper (W1)

3. Take oven dried soil sample (which is cooled in a desiccator) about 25gm when the 250ml volumetric flask is used, about 10gm when 50cc stoppered bottle is used or 100gm when 500ml pyconometer is used.

4.  Transfer the soil sample to the bottle. Find the weight of the bottle and soil (W2).

4.  Put 10ml of distilled water in the bottle to allow the soil to soak completely. Leave it for about 2 hours.

5.  Again fill the bottle completely with distilled water put the stopper and keep the bottle under constant temperature water baths (Tx0 ).

6.  Take the bottle outside and wipe it clean and dry note. Now determine the weight of the bottle and the contents  (W3).

7.  Now empty the bottle and thoroughly clean it. Fill the bottle with only distilled water and weigh it. Let it be W4 at temperature (Tx0 C).

8.  Repeat the same process for 2 to 3 times, and determine specific gravity of the soil. Report the average Specific Gravity.

 

Note: The specific gravity of the soil particles lie with in the range of 2.65 to 2.85. Soils containing organic matter and porous particles may have specific gravity values below 2.0. Soils having heavy substances may have values above 3.0. 

 

 

SAMPLE No.                                                                                       DATE:

NAME OF WORK:

DESCRIPTION OF SAMPLE

LOCATION                                         BORE No.                                DEPTH

 

TEST No.

1

2

3

TEMPERATURE  ºC

 

 

 

BOTTLE No.

 

 

 

WEIGHT OF SP.GR. BOTTLE G(W1)

 

 

 

WEIGHT OF SP. GR. BOTTLE + SOIL  G(W2)

 

 

 

WEIGHT OF SP. GR. BOTTLE + SOIL + WATER   G(W3)

 

 

 

WEIGHT OF SP. GR. BOTTLE + WATER (W4)

 

 

 

SPECIFIC GRAVITY OF SOIL TEMPERATURE         ºC

 

      G's   =             (W2  -  W1 )          .

                    (W4 – W1) – (W3 – W2 )

 

 

 

SPECIFIC GRAVITY OF SOIL TEMPERATURE    27 ºC

  Gs = K27 x  G's                ( see K27 from Table I )

 

 

 

AVERAGE

 

 

REMARKS