Evaluation of initial specimen condition and its effect on consolidation properties of saturated clay

The reliability of results of laboratory tests on soils depends on the specimen quality or the initial specimen condition. The quality of specimens prepared using different methods, from clay samples extracted using different techniques and subjected to different periods of storage, can be evaluated based on the measurement of residual porewater pressure. For a laboratory-fabricated normally consolidated clay, the residual porewater pressure decreases when using an inferior sampling technique or preparation method and when the storage time increases, with the effect from the method of specimen preparation dominating. Results of oedometer tests indicate that consolidation properties are noticeably affected by the initial specimen condition, and reasonably strong correlations exist between the preconsolidation pressure and the coefficient of volume compressibility of the clay and the residual porewater pressures in the test specimens. These corrections can be potentially applied to natural clays, although prior verification is necessary.