Objective
For determination of specific gravity of soil solids by pycnometer method.
Reference Standard
IS : 2720 (Part 4) – 1985 – Method of test for soil (Part 4-Grain size analysis)
Equipment & Apparatus
- Pycnometer
- Sieve(4.75 mm)
- Vaccum pump
- Oven
- Weighing balance
- Glass rod
Preparation sample
After receiving the soil sample it is dried in oven at a temperature of 105 to 1150C for a period of 16 to 24 hours.
Procedure
- Dry the pycnometer and weigh it with its cap(W1)
- Take about 200 g to 300 g of oven dried soil passing through 4.75mm sieve into the pycnometer and weigh again(W2)
- Add water to cover the soil and screw on the cap.
- Shake the pycnometer well and connect it to the vaccum pump to remove entrapped air for about 10 to 20 minutes.
- After the air has been removed, fill the pycnometer with water and weigh it (W3).
- Clean the pycnometer by washing thoroughly.
- Fill the cleaned pycnometer completely with water upto its top with cap screw on.
- Weigh the pycnometer after drying it on the outside thoroughly(W4).
Calculation
The Specific gravity of soil solids (Gs) is calculated using the following equation.
Where
W1=Empty weight of pycnometer
W2=Weight of pycnometer + oven dry soil
W3=Weight of pycnometer + oven dry soil + water
W4=Weight of pycnometer + water full
Report
The result of the specific gravity test is reported to the nearest two digits after decimal.
Safety & Precautions
- Soil grains whose specific gravity is to be determined should be completely dry.
- If on drying soil lumps are formed, they should be broken to its original size.
- Inaccuracies in weighing and failure to completely eliminate the entrapped air are the main sources of error. Both should be avoided.
What is the temperature value to determine specific gravity of soil
you stated wrong formula …….
Tq
Specific gravity formula is wrong….
Sp.gr. = Wt of dry soil/equivalent wt of standard fluid
= (w2-w1)/(w4-w1)-(w3-w2)
ur wrong.
Same thing if u un braket it the results will same
very helpful blog for civil engineering students . thank you