Blue clay soil is a type of expansive soil characterized by its bluish-purple color and high absorptive property. This enables the soil to soak up water in large quantities, which results in an increase in the soil's volume.
In the United States, blue clay soil is predominantly found in Utah's southern region. This dried-up layer of earth is composed of extremely small particles that are associated with caliche and bentonite soil formations. The sediments comprising blue clay soil are deposited by prehistoric rivers and lakes, including materials derived from volcanic ash.
Blue clay soil causes destructive effects on paved surfaces, walkways and structural foundations. Homes and other buildings that are constructed in a relatively undeveloped area are prone to serious damage.