Simulation of fabric in sedimented clays

Abstract

Sedimentation of clays in natural water bodies leads to the formation of sediments which exhibit different types of fabric (i.e., the arrangement of clay platelets). As the overall engineering behavior of clays is strongly dependent on their fabric, the study of sedimentation of clays and parameters influencing their settling characteristics becomes important. With this in view, sedimentation tests were conducted in the laboratory to study settling characteristics of different types of clays in aqueous suspensions of varying electrolyte concentrations. The settling characteristics, defined in terms of the volume of the sediments at the end of the test, were correlated with the ionic strength of the suspension and its zeta potential to obtain qualitative information about its fabric. Further, Impedance Spectroscopy (IS) and Mercury Intrusion Porosimetry (MIP) were conducted on these sediments to quantify their fabric and the results have been compared vis-à-vis those obtained by conducting similar investigations on the naturally occurring clay sediments, collected from offshore locations. It has been observed that by employing the anisotropy coefficient, which is the ratio of electrical conductivities of the specimen in the transverse and longitudinal directions of sedimentation, the particle orientation and the fabric anisotropy of sediments can be quantified. This study demonstrates the utility of the methodology, based on IS and MIP in tandem, for quantifying the fabric of clay sediments.