Oven Drying Method of Soil : Lab Procedure, Observation & Calculations

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: Liquid Limit Test of Soil

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