The mechanics of an Italian silt: an example of 'transitional' behaviour

By controlling the particle size distribution of an Italian silt, the influence of grading on its behaviour was investigated. As the clay content was reduced, the behaviour changed from a typical clay mode to a transitional form between that of clays and sands that had previously been seen only for gap-graded soils, emphasising that this type of behaviour is possibly much more extensive than previously thought. The work has highlighted several features of transitional behaviour, and in particular that unique normal compression and critical state lines do not exist, that Rendulic's principle does not apply, and that drained and undrained tests do not reach unique ultimate states.