Undrained Strength Characteristics of Compacted Bentonite/Sand Mixtures

This paper describes the results from a series of triaxial tests that were conducted to measure the shear strength of engineered bentonite/sand mixtures having clay contents of 15%, 25% and 50% by dry weight of the mixture. The field compaction process for each of these mixtures was simulated using a laboratory Proctor compaction approach. Proctor mold specimens were prepared using three different compactive efforts, corresponding to the "Low Energy", Standard Proctor, and Modified Proctor test procedures that were utilized. Using a sampling and trimming process, three triaxial specimens were prepared from each of the compacted Proctor specimens. Unconsolidated-undrained triaxial tests were then conducted on these specimens over a range of confining pressures to determine total stress shear strength parameters. Results from this study illustrate the effects of clay/sand mix proportion, compaction moisture content, compaction energy, and confining pressure on the shear strength and stress-strain behavior of compacted bentonite/sand mixtures.