Pore Size Distribution of Clayey Soils Measured by Mercury Intrusion Porosimetry and its Relation to Hydraulic Conductivity

Abstract

Pore Size Distribution (PSD) of naturally deposited clayey soil samples recovered from various parts of the world and at varying depths was measured by Mercury Intrusion Porosimetry (MIP). In addition to naturally deposited samples, the artificially mixed soils, namely Singapore clay with Toyoura sand or diatomite, are studied in order to know the influence of grain size component on the PSD. Characteristics of the PSD were represented by the mean pore size (Dp50). As an application of the PSD characteristics to practical geotechnical engineering, an attempt has been made to relate the hydraulic conductivity (k) with the PSD. The following interesting findings are obtained: With an increase in the consolidation pressure (p'), Dp50 also decreases in the same manner as that of the e-log p' relation. The range of Dp50 for naturally deposited soils is relatively narrow, namely between 0.03 and 2μm, except for London clay which is an old deposit clay, i.e., Tertiary. It is found from the artificially mixed soils that Dp50 generally increases with an increase in silt and sand content. There is a unique relation between the hydraulic conductivity (k) and nDp502, where n is the porosity.