Determination of specific gravity of soil

OBJECTIVE :

 To determine the specific gravity of soil fraction passing 4.75 mm I.S sieve by Pycnometer.

 

 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 USED
1. Pycnometer
2. Balance to weigh the materials (accuracy 10gm).
3. Wash bottle with distilled water.
4. Alcohol and ether.

PROCEDURE

➤ Clean and dry the pycnometer
➤ Wash the pycnometer with water and allow it to drain.
➤Wash it with alcohol and drain it to remove water.
➤ Wash it with ether, to remove alcohol and drain ether.
➤ Weigh the pycnometer (W1)
➤Take about 200 gm of oven-dried soil sample which is cooled in a desiccator. Transfer it to
the pycnometer. Find the weight of the pycnometer and soil (W2).
➤ Put 10ml of distilled water in the pycnometer to allow the soil to soak completely. Leave it
for about 2 hours.
➤ Again fill the pycnometer completely with distilled water put the stopper and keep the
pycnometer under constant temperature water baths (Tx0).
➤ Take the pycnometer outside and wipe it clean and dry it. Now determine the weight of the
pycnometer and the contents (W3).
➤ Now empty the pycnometer and thoroughly clean it. Fill the pycnometer with only distilled
water and weigh it. Let it be W4 at temperature (Tx0 C).

 OBSERVATIONS :

 Average specific gravity at Tx 0 C

 CALCULATIONS

 

specific gravity of soil = (Density of water at 27॰c)/Weight of water of equal volume.

 Repeat the same process for 2 to 3 times, to take the average reading of it.

 RESULT
Specific Gravity of given soil = (.........)