2. Sand Bath Method

• This is a field method used in the determination of the rough value of water content in the field, where the facility of an oven is not available.

Procedure:

1. The soil sample collected in the container is placed on a sand bath.

2. A kerosene stove is used to heat the sand bath.

3. The side gets dry in ½ - 1 hour of time.

4. The water content is determined using the above equation:(3.1).

Limitations: 

1. No control on temperature. Therefore, higher temperatures may break the crystalline structure of soils.

2. Not suitable for organic soils or soils containing gypsum in higher percentages.

2. Alcohol Method

• This is also a crude field method.

Procedure:

1. The wet soil sample is collected in an evaporating dish.

2. It is then mixed with a sufficient quantity of methylated spirit (Alcohol).

3. The mixture is ignited and the dishes are properly covered.

4. During ignition, the mixture is stirred using a wire.

5. The water content is determined using the above equation:(3.1) in the same way but in this case, the container is replaced by a dish.

Note: Limitations same as in 2nd method.

3. Calcium Carbide Metho

• This is a field method used in the quick determination of water content for the purpose of proper field control such as in the case of compaction of an embankment. This method is also known as the Rapid Moisture Method.

Procedure:

1. A wet soil sample of 6 g is collected in an air-tight container aka moisture tester.

2. It is now mixed with a sufficient quantity of fresh Calcium Carbide Powder.

3. The mixture is thoroughly mixed by shaking it vigorously. 

4. The moisture present in the soil and the calcium carbide produces acetylene gas  during the shaking of the mixture.

4. Radiation Method

• This is also a field method extremely useful in the determination of the water content of the soil in the in-situ condition. 

Procedure:

1. In this method, two boreholes at some required distance apart are dug in the soil whose water content is to be determined.

2. Then two steel casings, A and B are placed in the boreholes. Small holes are made in both the casings facing each other.

3. In casing A, a device containing radioactive isotope material (such as Cobalt 60) is placed in the capsule is lowered.

4. In the same way, a device comprising a detector is lowered in casing B.

5. Now, the radio-active device is activated and it emits neurons which travel towards casing B through the soil.

6. When these neutrons strike the hydrogen atoms of water present in the sub-soil, they lose energy.

7. The loss of energy by the neurons is detected by the device in the casing B which is calibrated to directly gives the water content of the soil.