Causes of Clay Sensitivity

Factors were examined leading to differences between undisturbed and remolded clay fabrics and interparticle forces. A consideration of available knowledge would suggest that there are eight different mechanisms which may lead to development of sensitivity. Of those indicated only two—leaching of salt water from marine clays and the introduction of dispersing chemicals, either through decomposition of material already present or by leaching into the clay—would appear adequate to account for extra quick clays. Ion exchange effects, particle arrangements induced by physical factors only, and cementation may lead to slightly quick clays, but the more usual contribution is probably much smaller. The remainder—silt skeleton-bond clay structure, thixotropic hardening, and weathering—appear able to account for only medium sensitivities. The total sensitivity of a given undisturbed clay may be made up of contributions from several causes.