EXPERIMENT 2 , Test Name: SPECIFIC GRAVITY DETERMINATION , soil and foundation
This lab is performed to determine the specific gravity of soil by using a pycnometer. Specific gravity is the ratio of the mass of unit volume of soil at a stated temperature to the mass of the same volume of gas-free distilled water at a stated temperature.
1. Pycnometer with capacity of (250 – 500) ml.
2. ,Balance of 0.01g readability ‘and.
3. Dry oven with temperature (110 5) .
4. Thermometer capable of measuring the temperature, readable to the nearest 0.1 .
5. Air removal apparatus, (Vacuum pump or hot plat).
8. Sieve No. 4
1. Determine and record the weight of the empty clean and dry pycnometer, WP.
2. Place 100g of a dry soil sample (passed through the sieve No. 4) in the pycnometer. Determine and record the weight of the pycnometer containing the dry soil, WPS.
3. Add distilled water to fill about half to three-fourth of the pycnometer. Soak the sample for (20-30) minutes, or mix the soil water mixture by malt mixer about (5-10) min.
4. Apply a partial vacuum to the contents for 10 minutes, to remove the entrapped air, or use hot plate to remove the entrapped air by boili .
5. Stop the vacuum or hot plate and carefully remove the pycnometer.
soil and foundation
6. Fill the pycnometer with distilled (water to the mark), clean the exterior surface of the pycnometer with a clean, dry cloth. Determine the weight of the pycnometer and contents, WB, and record the temperature (T1).
7. Empty the pycnometer and clean it. Then, fill it with distilled water only (to the mark). Clean the exterior surface of the pycnometer with a clean, dry cloth. Determine the weight of the pycnometer and distilled water, WA, and record the temperature (T2) which must be same as temperature in step 6.
8. If the temperature was not equal at step 6 &7, the WA must be correct as follow:
9. Empty the pycnometer and clean it
d- Data Analysis:
Calculate the specific gravity of the soil solids using the following formula:
W0 = weight of sample of oven-dry soil = WPS – WP
WA = weight of pycnometer filled with water
WB = weight of pycnometer filled with water and soil.
NOTE : repeat the sequence outline of the test for additional values of Gs until you have two value which are within 2% of each other, define as follows:
Date Tested: APRIL 30, 2022
Tested By: HM Class, Group D
Project Name: HM Lab
Sample Number: A ,B
Sample Description: Gray silty clay