Specific Gravity | Specific gravity of a soil (GS) is the ratio of the mass density of solids to mass density of water.


Specific gravity of a soil (GS) is the ratio of the mass density of solids to mass  density of water.



Objective:

 To determine the specific gravity of given soil by Density Bottle Method. 

Theory:
 Specific gravity of a soil (GS) is the ratio of the mass density of solids to mass 
density of water. Specific gravity is usually reported at 20°C. Specific gravity is 
determined as


Where,
 m1 = mass of empty bottle, 
m2 = mass of bottle and dry soil, 
m3 = mass of bottle, soil and water, and 
m4 = mass of bottle filled with water only. 

m1 = mass of empty bottle,  m2 = mass of bottle and dry soil,  m3 = mass of bottle, soil and water, and  m4 = mass of bottle filled with water only.


Apparatus: 

(1). 50ml Specific gravity bottle, (2). Distilled water, (3). Hot plate, (4). Balance (with 
0.01g sensitivity), (5). Oven, and (6). Vacuum desiccator 

Procedure 

1. Weigh a clean and dry density bottle empty (m1). 
2. Take about 15 g of oven dry soil in the bottle. Take the combined weight of soil and 
bottle (m2). 
3. Add deaired distilled water to cover soil (half full) and then boil it on the hot plate for 
about 30 minutes. Remove the stopper while boiling and avoid spurting. 
4. Cool the bottle to room temperature, fill it completely with deaired distilled water and 
replace the stopper correctly. Wipe the surface of the bottle and weight the bottle 
(m3). 
5. Empty the contents and clean the density bottle thoroughly. Fill the bottle with 
distilled water and weight (m4). 
6. Fill the record sheet given and calculate the specific gravity. 
7. If given the time, repeat the above steps 2 to 6 using a dry density bottle.

Fill the record sheet given and calculate the specific gravity.  7. If given the time, repeat the above steps 2 to 6 using a dry density bottle.