The Oven Drying Method is used to determine the water content in a specific soil.
This method is necessary to understand the bearing capacity as well as the probable settlement of the soil. It is carried out in the laboratory itself.
1. Apparatus Required
i. Thermostatically controlled oven maintained at a temperature of 110 ± 5oC
ii. Weighing balance, with an accuracy of 0.04% of the weight of the soil taken
iii. Air-tight container made of non-corrodible material with a lid
iv. Tongs
2. Quantity of Soil Required for Water Content Determination
| Size of particles more than 90% of passing | Minimum Quantity ( grams) |
| 425-micron sieve | 25 |
| 2 mm sieve | 50 |
| 4.25 mm sieve | 200 |
| 10 mm sieve | 300 |
| 20 mm sieve | 500 |
| 40 mm sieve | 1000 |
3. Procedures in Oven Drying Method of Soil
The procedure for the oven drying method can be listed as follows:
i. The air-tight container along with its lid must be first weighed(W1).
ii. The specimen sample is then taken in the container, and the weight of a container along with the lid and sample is taken, say W2.
iii. Then, the container is left in the oven. The specimen is dried to a constant weight at temperatures ranging from 105 to 110 degrees Celsius for about 16 to 24 hours.
iv. The container, along with the lid and the dried sample, are finally weighed(W3).
v. The moisture content is then calculated using the following formula:
W= [ (W2-W3) / (W3-W1) ] * 100
Where,
W1= Weight of the container with a lid in grams
W2= Weight of the container with lid and wet sample in grams
W3= Weight of the container with lid and dry sample in grams
Note: To get an accurate value, a minimum of three soil samples should be taken to test, and average water content should be taken as a result.
4. Observations and Calculations of Oven Dry Method
| Sl. No. | Observations and Calculations | Determination No. | ||
| 1 | 2 | 3 | ||
| Observation | ||||
| 1 | Container No. | |||
| 2 | Weight of empty container (W1) | |||
| 3 | Weight of container + soil (W2) | |||
| 4 | Weight of container + dry soil (W3) | |||
| Calculations | ||||
| 5 | Weight of water Mw= M2 – M3 | |||
| 6 | Weight of solids, Ms= M3 – M1 | |||
| 7 | Water content= (5)/(6)x100 | |||
5. Result of Oven Dry Method
Water content of the given soil sample = ______%
6. Precautions in Oven Drying Method
a. Temperature of the oven should be maintained between (105°-110°)C.
b. Wait to cool for the dry soil in a container to remove from the oven ( or use tongs).
c. For accurate calibration, the thermostat should be kept on checking regularly.
| Read Also: Soil Tests for Road Construction |
