Water content is the amount of water in a given material. In the field of construction, moisture content is an important factor to be considered for a variety of reasons, such as the assessment of the quality of building materials, the design of building components, and the evaluation of the performance of building systems.

Official Methods

There are a number of official methods are available for determining the moisture content of materials. These methods are typically based on the gravimetric method, which involves measuring the weight of a sample before and after it has been dried to a constant weight.

• **ASTM D2216:** Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass
• **ASTM D4643:** Standard Test Method for Determination of Water (Moisture) Content of Soil by Microwave Oven Heating
• **ASTM D6443:** Standard Test Method for Determining the Moisture Content of Soil by Loss on Drying
• **AASHTO T 265:** Standard Method of Test for Dry Preparation of Disturbed Soil Samples for Test
• **AASHTO T 287:** Standard Method of Test for Moisture-Density Relations of Soils Using a Vibratory Hammer

Gravimetric Method

The gravimetric method is a simple and accurate method of determining moisture content. It is based on the principle that the weight of a sample of material will decrease as it loses moisture.

To determine moisture content using the gravimetric method, the following steps are typically followed.

• A sample of the material is weighed.
• The sample is dried to a constant weight. This can be done in an oven, a vacuum oven, or a microwave oven.
• The dried sample is weighed again.
• The moisture content is calculated as the difference between the weight of the wet sample and the weight of the dry sample, divided by the weight of the dry sample.

The gravimetric method of moisture content determination is a simple and accurate method that can be used for a wide variety of materials.