Rheologic testing of wet kaolin reveals frictional and bi-viscous behavior typical of crustal materials

Abstract

New rheological data for wet kaolin support its use in analog table-top experiments that simulate deformation of the Earth's crust. Creep tests at small strain reveal that wet kaolin (62-66% water by mass) exhibits both elastic and viscous deformation characteristic of a Burger's material. When sheared to failure, the shear strength is relatively insensitive to the strain rate. The shear strength appears sensitive to the amount of initial compaction within the rheometer, which may indicate a normal-stress dependency typical of frictional materials. Stepped velocity tests at large strain demonstrate velocity weakening rate and state frictional behavior after yielding. Because the wet kaolin exhibits deformation characteristic of both frictional materials and bi-viscous materials, this material is well suited to simulate a variety of crustal deformational processes in scaled analog experiments. Copyright 2012 by the American Geophysical Union.