Evaluation of a Centrifuge Consolidation Technique for Preparation of Direct Simple Shear Samples

A series of consolidation tests were conducted on kaolinite samples consolidated using centrifuge sedimentation/consolidation techniques. Samples were consolidated under a one-dimensional flow regime using centrifugal forces (as applied using a drum centrifuge) to facilitate consolidation. The drum centrifuge consists of six (6) 4 inch (10.16 cm) diameter by 5.5 inch (13.97 cm) deep aluminum cups in which 2.625 inch (6.67 cm) diameter by 5.25 inch (13.34 cm) tall acrylic consolidation cups were inserted. Slurry samples were allowed to consolidate by spinning the centrifuge at 500 revolutions per minute, corresponding to a relative centrifugal force (RCF) ranging from 44.14 to 66.57 within the sample. Moisture content and unit weight profiles were obtained after spinning the centrifuge for 7 hours, 16 hours, 24 hours, 36 hours, 40 hours, and 48 hours. An initial slurry sample with water content of 44 percent and initial unit weight of 106 pcf (16.7 kN/m³) became a soil sample with final water content of 30 percent and final unit weight of 118 pcf (18.5 kN/m³) after spinning in the centrifuge for 48 hours. This centrifuge consolidation technique proved successful in preparing soil samples to be used for direct simple shear strength tests in a reduced amount of time (as compared to traditional static weight consolidation techniques).