Water Content of soil and determination

Water content or moisture content of the soil is defined as the ratio of the weight of water to the weight of solids in a given mass of soil. It is usually expressed as a percentage

$w=\frac{W_w}{W_s}\times100$

where (W_w) is the weight of water and (W_s) is weight of solids

Range of (w):

Water content could not be less than 0, and go up to any limit. Hence limit of this is (w\ge0)

Water content determination

This is a very important and routine test. To perform other tests like shear strength test, triaxial test etc. on soil one have to perform this. It is an important soil parameter that influences the behavior of soil, particularly clayey soil.

Oven-drying method

It is the simplest method of determining the moisture of the soil, hence used more frequently. This soil sample is dried in an oven under controlled condition. Keep the temperature of oven between (105-110^\circ\mathrm{C}). Temperature higher than (110^\circ \mathrm{C}) may break the crystalline structure of clay particle. This may cause loss of chemically-bound water of crystallization.

1. Take a clean and non-corrodible container to heat the moist soil sample.
2. Use about 30-40 gram of soil in a container and weighed.
3. Put the soil sample along with container in the oven for drying.
4. Keep the oven dried container in a desiccator for cooling.
5. Weigh the container with a dried sample .

(W_1 =) weight of container

(W_2=) weight of container with moist soil

(W_3=) weight of container with dried soil

weight of water, (W_w = W_2-W_3)

weight of solids, (W_s=W_3-W_1)

water content, (w)

$w=\frac{W_2-W_3}{W_3-W_1}\times100(\%)$

Also read: void ratio