The water content w, also called the moisture content, is defined as the ratio of weight of water W
w to the weight of solids (W
s or W
d) in a given mass of soil.
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| Equation 1. Natural water content expressed by weights |
The water content is generally expressed as a percentage. However, when used in the formulae giving relationship between certain quantities, it may also be expressed as a fraction. Rewriting Eq. 1, we have Eq. 2.
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| Equation 2. Water content as a fraction |
The usual procedure to find the natural water content is to take a mass of about 20 g to 30 g of soil sample in a container and determine its mass M very accurately. The soil sample is then kept in an oven (105°C–110°C) for about 24 hours so that it becomes perfectly dry. Its dry mass Md is then determined and the water content is calculated from the relation,
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| Equation 3. Natural water content expressed by masses |
