Effect of Fabric on the Swelling Characteristics of Highly Plastic Clays

This paper provides an assessment of the influence of fabric on the swelling characteristics of clays. Specifically, the evaluation involves clay specimens compacted wet and dry of optimum (to achieve a comparatively dispersed and flocculated structures, respectively). In addition, characterization involved specimens collected in the field using Shelby tubes driven into an expansive soil deposit. The clay specimens were moisture-conditioned to the same dry state after compaction and before testing using a centrifuge-based inundation approach. The results from moisture-conditioned specimens were compared against those from specimens that were initially prepared dry prior to inundation. The results from specimens prepared to a dispersed structure show primary swelling of the same magnitude as those prepared to a flocculated structure. However, the specimens prepared to a dispersed structure took longer to reach the end of primary swelling. The results from field-collected undisturbed specimens show similar time response as the compacted, moisture-conditioned specimens, but reveal slightly higher swelling than specimens reconstituted to the same initial conditions. Overall, the experimental results show that the soil fabric of highly plastic clays affects primarily the time needed to reach the end of primary swelling but not the magnitude of swelling for laboratory reconstituted specimens.