Atterberg Limit Test

Significance:

The Swedish soil scientist Albert Atterberg originally defined seven “limits of consistency” to classify fine-grained soils, but in current engineering practice only two of the limits, the liquid and plastic limits, are commonly used.  (A third limit, called the shrinkage limit, is used occasionally.)  The Atterberg limits are based on the moisture content of the soil.  The plastic limit is the moisture content that defines where the soil changes from a semi-solid to a plastic (flexible) state.  The liquid limit is the moisture content that defines where the soil changes from a plastic to a viscous fluid state.  The shrinkage limit is the moisture content that defines where the soil volume will not reduce further if the moisture content is reduced.  A wide variety of soil engineering properties have been correlated to the liquid and plastic limits, and these Atterberg limits are also used to classify a fine-grained soil according to the Unified Soil Classification system or AASHTO system.