What does the term swell potential refer to in expansive soils?

Swell potential refers to the tendency of expansive soils, such as clay, to increase in volume when they absorb moisture. This phenomenon occurs because certain minerals in clay soils, particularly smectite, expand significantly when water is added. As the moisture content increases, the water molecules infiltrate the soil structure, causing it to swell. This characteristic is crucial for engineers and construction professionals to understand, as it can influence the stability and performance of structures built on or within these soils.

On the other hand, the other options deal with properties or behaviors that do not directly correlate with the concept of swell potential. For instance, soil excavation relates to how easily soil can be removed, which does not affect or reflect the volume changes upon moisture addition. The tendency of soil to contract when dried addresses a different behavior than expansion, focusing instead on shrink-swell cycles without directly defining swell potential. Finally, measuring soil density pertains to the mass of soil per unit volume, which is unrelated to how moisture affects the soil’s capacity to swell. Understanding swell potential is vital for predicting and managing the impacts of moisture changes in expansive soils, essential for site planning and construction design.