Water Content (w)

The water content (w), also known as natural water content or natural moisture content, is the ratio of the weight of water to the weight of the solids in a given mass of soil. This ratio is usually expressed as percentage. When voids are completely filled with air, water content is equal to zero (dry soil).

w(%) = (M_W / M_S) * 100

Laboratory Determination of Moisture Content

Apparatus Required

• Non-corrodible container;
• Digital Weight Machine (accuracy of 0.04% of mass of sample);
• Electric oven, maintain the temperature between 105⁰ C to 110⁰ C

Test Procedure

The test procedure of the "Oven Dry method" to find the moisture content of soil consists of the following steps:

1. Clean and dry the container and weigh it (W₁).
2. Take a specimen of the sample in the container and weigh it (W₂).
3. Place the container in the hot air oven, arrange temperature to 110^o ± 5^o C and allow it to dry for a period varying with the type of soil (usually 24 hours).
4. Record the final constant weight (W₃) of the container with dried soil sample.