ABSTRACT
The ability of material to change shape continuously under the influence of an applied stress, and to retain the new shape on removal of the stress is plasticity. This distinguishes it from an elastic material, which regains its original shape on removal of a stress, and from a liquid, which does not retain its own shape. Only the very small particles of soils of the right mineralogy, clays, and to some extent silt exhibit plastic behaviour at low stresses. The deformation behaviour of a soil at given water content is called its consistency. Consistency is the resistance to flow of the soil and also an indication of its deformation behaviour. Consistency is related to the force of attraction between individual particles or aggregates of these particles and geometrical interferences. Different soils have different consistency at different water contents, and the specification of this condition gives some information about the type of soil material.
