Influence of Initial Water Content and Specimen Thickness on the SWCC of Fine-Grained Soils

Abstract

Earlier researchers have demonstrated that the compaction effort and water content, type of soil and mineralogy, void ratio, fabric, and stress history influence the soil-water characteristics curve (SWCC) of fine-grained soils to a great extent. However, it should be noted that compacting the soil and retrieving specimens from the compacted mass for suction measurements is a tedious task. Also, many times, identical soil specimens with similar compaction states may result in varied pore-size distribution characteristics. Hence, for establishing the SWCC, soil specimens in the form of slurry of adequate consistency would be quite handy, particularly for maintaining uniformity in specimen preparation. With this in view, the current study was carried out to understand the influence of initial water content on the SWCC and to recommend its best suited value for conducting experiments. It has also been noted that suction measurement devices, such as pressure membrane extractor and the dew point potentiameter WP4, have limitations associated with the thickness of the specimen, which may become an important and deciding parameter. Hence, in this study, SWCCs were established for commercially available kaolin and bentonite clays by varying the initial water contents and thickness of their specimens. Details of the methodologies adopted for these investigations are presented in this paper. These investigations reveal that the initial water content influences only the initial portion of the SWCC for soil suction less than 500 kPa, while the specimen thickness does not significantly influence the shape of the SWCC. It has also been demonstrated that specimens prepared from the initial slurried state facilitate uniformity in suction measurements.