TO DETERMINE THE SPECIFIC GRAVITY OF THE SOIL PARTICLES USING PYCNOMETER:

TITLE:

TO DETERMINE THE SPECIFIC GRAVITY OF THE SOIL PARTICLES USING PYCNOMETER:

OBJECTIVES:

1. To find out the specific gravity of solids.

2. To be able to do some lab test of soil.

THEORY:

Specific gravity is the ratio of the mass of a given volume of dry soil solid to the mass of an equal volume of distilled water at `4^0C`

A pycnometer or constant volume method has found to be the most reliable for the determination of specific gravity.

 let,

`M_1=`mass of pycnometer

`M_2=` mass of pycnometer+dry soil

`M_3=`mass of pycnometer+soil+water

`M_4=`mass of pycnometer+water

Specific gravity is an important property by which void....Show More

TITLE:

TO DETERMINE THE SPECIFIC GRAVITY OF THE SOIL PARTICLES USING PYCNOMETER:

OBJECTIVES:

1. To find out the specific gravity of solids.

2. To be able to do some lab test of soil.

THEORY:

Specific gravity is the ratio of the mass of a given volume of dry soil solid to the mass of an equal volume of distilled water at `4^0C`

A pycnometer or constant volume method has found to be the most reliable for the determination of specific gravity.

 let,

`M_1=`mass of pycnometer

`M_2=` mass of pycnometer+dry soil

`M_3=`mass of pycnometer+soil+water

`M_4=`mass of pycnometer+water

fig:Determination of specific gravity by using pycnometer

Specific gravity is an important property by which void ratio, porosity, degree of saturation, particle size distribution are determined. Moreover, it is useful in the study of quick sand condition and in the estimation of zero air void line in the compaction theory.

APPARATUS REQUIRED:

• Pycnometer, 

• I.S Sieve, 

• balance, 

• drying oven,

• Glass rod,

•  water

PROCEDURES:

1. The weight of empty pycnometer was found out say `M_1`.

2. The pycnometer was then filled with about 200 gram of dry sample of soil and weighted again, say `M_2`.

3. Water was then added in the pycnometer in such a way that it is half full of water. The air in the soil sample was then expelled by heating or by suction. The water was then added to its full capacity and pycnometer was weighed again say `M_3`. 

4. The pycnometer was filled with water only and its weight was determined, say `M_4`.

OBSERVATIONS:

Weight of empty pycnometer,`M_1=0.5057\ kg`

Weight of pycnometer+dry soil,`M_2=0.8787\ kg`

Weight of pycnometer+soil + water,`M_3=1.7797\ kg`

Weight of pycnometer + water,`M_4=1.5458\ kg`

CALCULATIONS:

The specific gravity of solids,G is given by:

$G=(M_2-M_1)/((M_4-M_1)-(M_3-M_2))$

$G=(0.8787-0.5057)/((1.5458-0.5057)-(1.7797-0.8787))$

$G=2.68$

RESULTS:

Thus, the specific gravity of the given soil sample was found to be `2.68`.

SOURCES OF ERRORS:

1. The value of specific gravity is dependent upon temperature. So its value may differ slightly at different temperatures. 

2. The water may not be added completely full of pycnometer i.e, constant volume may not be achieved.

3. There may be error while observing weight.

PRECAUTIONS:

1. The soil sample whose specific gravity is to be determined should be completed dry.

2. Dried soil taken for testing should have the soil grains of its original size. So, if on drying soil humps are formed, they should be broken to original size.

3. Gap should be properly screwed with washer to avoid any leakage.

CONCLUSIONS:

Thus,the specific gravity of soil solids was determined in the laboratory using pycnometer i.e, constant volume method.