Moisture Content

The moisture content test is to determine the amount of water present in soil expressed as a percentage of the mass of dry soil. The moisture content of a soil is assumed to be the amount of water within the pore space between the soil grains which is removable by oven-drying at a temperature not exceeding 110°C. The moisture content has a profound effect on soil behaviour.

The oven-drying method is regarded as standard laboratory practice.

Required equipment

•        a drying oven with temperature of 105°C to 110°C

•        a balance readable to 0.1 g

•        a metal container

Test Procedure

1. Clean and dry the container, then weigh it to the nearest 0.1 g (m₁)
2. A representative sample shall be crumbled and loosely placed in the container.
   1. For fine-grained soils, the sample weight shall be min. 30 g.
   1. For medium-grained soils, the sample weight shall be min. 300 g.
   1. For coarse-grained soils, the sample weight shall be min. 3 kg.
3. The container with the sample shall immediately be weighed (m2) and placed in the oven to dry at 105°C for a minimum of 12 hours.
4. After drying, weigh the container and the contents (m₃)

Calculations

Calculate the Moisture Content of the soil specimen, w, as a percentage of the dry soil mass to the nearest 0.1%, from the equation:

where

m₁  is the mass of the container (in g)

m₂ is the mass of the container and wet soil (in g)

m₃ is the mass of the container and dry soil (in g)

References

 The United Republic of Tanzania ministry of works, Laboratory Testing Manual 2000, Novum Grafisk AS, Skjetten Norway