Tensile strength of some compacted fine-grained soils

Compacted soils are generally unsaturated soils, at least initially after compaction, although they may become saturated over time as a result of rising water tables, surface water infiltration, etc. The tensile strength of compacted soils can be an important design parameter for earth dams and embankments and should be considered in the design and development of earthwork specifications. A laboratory study was performed to determine the tensile strength of four compacted soils representing a wide range of geologic materials including an alluvial clay from Mississippi, a Piedmont residual soil from Georgia, a loess soil from Nebraska and a lacustrine clay from Massachusetts. Proctor curves for each soil were developed using Reduced, Standard, and Modified compaction energy. Following compaction the tensile strength of each specimen was determined using the Double Punch Test. The results showed that the Double Punch Test is most reliable near the Optimum Water Content. The measured tensile strength for each water content in the range of OWC +/-6% was normalized by the tensile strength at the Optimum Water Content for each level of compaction effort. The results showed a linear trend between Normalized Tensile Strength and the deviation from the Optimum Water Content.