ABSTRACT
Soils are composed of three phases; solid minerals, water and air. The amount of water in soil can significantly influence soil behavior, especially for fine-grained soils such as clays, silty clays and silts. Water Content is a fundamental soil characteristic and should be performed on every sample collected as part of a project. The test often uses cuttings from specimens trimmed in the lab for other tests, such as consolidation or direct shear. Water Content of soils is a mass relationship and is defined as the ratio of the mass of water to the mass of oven dry solids expressed as a percent. The tests is also required as part of the compaction test (not covered in this manual) and is also conducted on samples collected in the field as part of a drilling and sampling program.
There are three common laboratory methods used to determine Water Content of soils: 1) convection oven; 2) microwave oven; and 3) gas carbide. The first two methods are used exclusively in the laboratory, while the gas carbide method may be used in the laboratory or in the field. Another method not covered in this manual is the determination of Water Content by direct heating by using a hot plate, heat lamp, gas stove, etc. This is covered by ASTM D4959 Standard Test Method for Determination of Water (Moisture) Content of Soil by Direct Heating Method.
