Thixotropic effects in a clay-water system

Fundamental aspects of thixotropic phenomena are described, and previous investigations of thixotropic behavior in soil systems are summarized. The complex nature of the thixotropic phenomena as well as its general occurrence in fine grained soils is described. As existing hypothesis for thixotropic behavior based on initial non-equilibrium conditions is examined. Experimental results, as determined from a testing program on the Putnam clay, verify this hypothesis. The rate and magnitude of thixotropic strength increases of the Putnam clay were determined. Shear strength determinations were made by the unconfined compression and laboratory vane shear tests. The results of the tests were compared and variations are explained. Results of the research program indicate that: 1) Water content is of primary importance in determining the rate of shear strength increase. 2) Aging leads to an increase in stiffness and ultimate strength. 3) Acquired sensitivity is greatest at small strains --Abstract, page ii