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which method is used to determination of water content when specific gravity of soil solids is known in advance.
Pycnometer method
Calcium carbide method
Sand bath method
Oven drying method
Pycnometer method
The Pycnometer method is a volumetric approach used to determine the water content of soil by utilizing the displacement principle. When the specific gravity of soil solids is known, the water content can be calculated by measuring the weight of the soil sample and the weight of the pycnometer filled with water and soil.
The Pycnometer method is a volumetric approach used to determine the water content of soil by utilizing the displacement principle. When the specific gravity of soil solids is known, the water content can be calculated by measuring the weight of the soil sample and the weight of the pycnometer filled with water and soil.
w=[M3тАЛтИТM4тАЛM2тАЛтИТM1тАЛтАЛ├ЧGGтИТ1тАЛтИТ1]├Ч100 тАФ Relationship between water content (w), specific gravity (G), and mass readings.
The method is based on the principle of displacement, where the volume of water displaced by soil solids is related to their specific gravity. By filling the pycnometer with the soil sample and then filling the remaining space with water, we can establish a relationship between the weight of soil, water, and the specific gravity of the soil solids. Since the total volume of the pycnometer is known, the mass of water required to fill the voids can be calculated, leading to the water content.
Pycnometer method is primarily used for cohesionless soils (coarse-grained).
It requires the knowledge of the specific gravity of soil solids (G).
It is a rapid field method compared to the oven-drying method.
Not suitable for soils with high organic content or fine-grained clays where air entrapment is difficult to remove.
Quick and field-friendly.
No complex heating equipment required.
Less accurate than the Oven Drying method.
Difficulty in removing entrapped air bubbles from the soil paste.
Requires pre-determined G value.
Routine field determination of water content for granular soils.
Quick site moisture checks for earthwork construction.
| Feature | Pycnometer | Oven Drying |
|---|---|---|
Accuracy | Moderate | High (Standard) |
The Oven Drying method is the most accurate laboratory method and is considered the standard.
The Calcium Carbide method is an extremely rapid chemical method, but does not require specific gravity, it relies on gas pressure measurement.
A is correct тАФ The Pycnometer method uses the relationship between soil weight, displaced water volume, and specific gravity to calculate water content.
Remember that while the Oven Drying method is the IS code standard, the Pycnometer method is unique because it incorporates G into its volumetric calculation.