The Atterberg Limits are the basic measure for the nature of a soil. By a series of experiments the Liquid Limit (LL) and Plastic Limit (PL) of a soil can be found, depending on water content. Although somewhat empirical, these values are used in a number of further values which are very useful in soil mechanics such as Plasticity index and Activity.

Somewhat arbitrary the Liquid Limit marks the change of a soil from a plastic to a viscous fluid, whilst the Plastic Limit is the point where the soil stops being a plastic and becomes a brittle solid.

Activity

The Activity (A) of a soil is the PI divided by the % clay present. Due to the different Specific surface values for different types of clay, which in turn controls how much wetting is required to move them across the Liquid Limit or Plastic Limit. From this one can predict the dominant clay present in a sample by the activity.

Geotechnical engineering | Soil mechanics | Soil physics

Límites de Atterberg