Correct Answer - Option 3 : 500ml flask is used only for fine grained soils
Concept:
Specific Gravity:
Specific gravity can be defined as the ratio of the weight of a given volume of soil solids at a given temperature to the weight of the equal volume of distilled water at that temperature. It can be written as G = \(\dfrac{\gamma_s}{\gamma_w}\)
1. Density bottle method:
- The specific gravity of solid particles can be determined in a laboratory using a density bottle fitted with a stopper having a hole.
- The density bottle of 50 ml capacity is generally used [ IS:2720 (part III) 1980].
2. Pycnometer method:
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Pycnometer method is used to determine specific gravity and water content both.
- This method is suitable for cohesionless soils.
- A pycnometer is a glass jar of 1-liter capacity that is fitted at its top by a conical cap made of brass.
- It has a screw-type cover and there is a small hole at its apex of 6 mm in diameter
Explanation:
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Density bottle method can be used for every type of soil, and it is the most accurate one.
- Flask and pycnometer are used for coarse-grained soil.
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Distilled water is used in the pycnometer test and kerosene is used for the density bottle method. When kerosene is used, its specific gravity is determined accurately by a separate test.
