Development of a Hydraulic Conductivity Placement Window using Centrifuge Techniques

A centrifuge soil testing device, currently operated by researchers at the University of Arkansas, was used to develop a technique to determine a hydraulic conductivity placement window. The purpose of this research was to develop a placement window by means of a centrifuge instead of by means of a panel board. Soil specimens were created at standard PRcotor energy and at 50 percent of Standard Proctor energy at -3 percent of optimum, -1.5 percent of optimum, two specimens at optimum, +1.5 percent of optimum, and +3 percent of optimum water content. Values of hydraulic conductivity for the respective specimens were determined to be 1.90E-08, 2.18E-08, 2.10E-08, 1.85E-08, 2.00E-08, and 1.80E-08. Specimens were observed to have been centrifuged at too large of a rotation speed which induced too high of stresses on the specimen, and too large of a gradient across the specimens. Piping, slurry formation, and resedimentation was observed in several of the specimens; specifically piping was observed in the specimens that had porous bronze filters instead of porous stone filters