Object: To determine the specific gravity of fine-grained soil by Density Bottle Method
Standard:
AASHTOT100-86
ASTMD854-70 BS1377
Apparatus:
- Density bottle
- Balance
- Oven
Theory:
Specific gravity is the ratio of mass of a given volume of a material at a stated temperature to the mass of the same volume of water at a stated temperature. It is very important and basic parameter to know the soil characteristics. Many laboratory experiments in soil mechanics required the determination of specific gravity, like hydrometer analysis, consolidation of soils etc.
Procedure:
- Clean and dry the density bottle.
- Wash the bottle with water and allow it to drain.
- Weigh the empty bottle (W1).
- Take about 100gm oven soil sample which is cooled in a desiccator. Transfer it to the bottle. Find the weight of the bottle and soil (W2).
- Put 500ml of distilled water in the bottle to allow the soil to soak completely. Leave it for about 2 hours.
- Now determine the weight of the bottle and the contents (W3).
- Now empty the bottle and thoroughly clean it. Fill the bottle with only distilled water and weigh it. Let it be W4.
Calculations:
𝑆𝑝𝑒𝑐𝑖𝑓𝑖𝑐 𝐺𝑟𝑎𝑣𝑖𝑡𝑦 =
𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑑𝑟𝑦 𝑠𝑜𝑖𝑙
𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑒𝑞𝑢𝑎𝑙 𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑤𝑎𝑡𝑒𝑟
𝑤2 − 𝑤1
𝑆𝑝𝑒𝑐𝑖𝑓𝑖𝑐 𝑔𝑟𝑎𝑣𝑖𝑡𝑦 = (𝑤2 − 𝑤1) − (𝑤3 − 𝑤4)
Where,
W1= wt. of empty bottle
W2= wt. of empty bottle + wt. of dry soil
W3= wt. of empty bottle + wt. of dry soil + wt. of water W4= wt. empty bottle + wt. of water
Observations:
1. Weight of empty bottle (W1) | = | gm | |
2. Weight of empty bottle + dry soil (W2) | = | gm | |
3. Weight of empty bottle + soil + water (W3) | = | gm | |
4. Weight of empty bottle + water (W4) | = | gm |
5. Specific Gravity (Gs) at 20C=
Result:
The specific gravity of soil sample is.
