An evaluation of compression-permeability characteristics in the intermediate concentration range by use of centrifugal and constant-rate compression techniques.

Abstract

The compression-permeability characteristics of a solid–liquid mixture can be obtained from the gravitational sedimentation test (in dilute region) and the C-P cell method (in concentrated region). In this paper, two new methods—the centrifugal method for the compression data and the constant-rate compression method for the permeability data—to obtain the characteristics in the intermediate concentration region between the two are presented. In the centrifugal test, the compression data in the intermediate region can be obtained by choosing suitable centrifugal acceleration and measuring the equilibrium height of a sediment. The data are in good agreement with those in the concentrated region. The gravitational sedimentation data, however, show higher porosity because of the friction between the sediment and the inner wall of a cylinder. In the constant-rate compression test, a material is compressed in a C-P cell for a given time at the rate at which the material is kept approximately homogeneous, followed by the permeability measurement. The permeability data based on this method can be combined with C-P cell data and the sedimentation data of an extremely dilute suspension.