Characterizing Monotonic Behavior of Pond Ash within Critical State Approach

Abstract

The monotonic behavior of pond ash was studied experimentally and with a particular focus on evaluating the applicability of critical state soil mechanics framework in synthesizing and modeling the observed mechanical behavior. Specimens were reconstituted with a paste deposition technique that closely mimics the wet disposal of dominantly fine coal ash in ash ponds. This technique can produce segregation-free specimens over a wide range of as-formed density states. The test results indicated that the observed behavior was similar to granular geomaterials, except that only nonflow behavior could be observed in undrained shearing. More importantly, a unique and consistent critical state line (CSL) in triaxial compression was obtained in both q-p′ and e-log(p′) planes irrespective of its drainage conditions, initial density states, and stress histories. The CSL in the e-log(p′) plane was used to predict behavior patterns. It was found that the state parameter, as defined relative to the CSL in e-log(p′) plane, correlates with important modeling parameters. Thus, this study unambiguously supports the applicability of critical state soil mechanics framework in synthesizing and modeling the behavior of pond ash.