Plasticity is the characteristic behaviour of a ceramic material to become permanently deformed after the application of an external force. This property is the most characteristic one in clays, and there are some factors that influence the plasticity and they should be considered in plasticity measurements:
- Water physical characteristics like, viscosity, surface tension…
- Particle size distribution of the solid sample and its specific surface
- Chemical and mineralogical composition of samples
- Effect of the additives added to the clay/water system
- Sample temperature
- The way to prepare the sample, particularly the energy used to mix and to process clay, water & additives
Plasticity is defined as the capacity to be deformed without being broken. Many methods available to measure it, and they are classified into two groups: direct and indirect methods.
Table1. Direct and indirect plasticity methods.