Geotechnical Properties of LAPONITE RD®

Abstract

This paper presents a synthetic smectite clay comparable in structure to the natural clay mineral hectorite that can be used in physical geotechnical models as a transparent soft clay surrogate. Upon dispersion with distilled water, the synthetic clay hydrates and swells, forming a transparent slurry that can then be consolidated. The transparency of the resulting consolidated slurry allows for non-intrusive observation of behavior within a physical model. Observations possible within the physical model include visualizing flow and the measurement of deformation using nonintrusive optical visualization techniques including digital image correlation. Initial synthetic clay concentrations from 4 to 4.5 % by weight were examined. These initial concentrations were further consolidated resulting in samples with higher concentrations by weight for use in various geotechnical laboratory tests. Due to the potential of the synthetic clay to be a soft clay surrogate, geotechnical laboratory testing typically used to characterize soft clays was performed on the solidified colloidal slurry including a series of laboratory vane tests, consolidation tests, and a series of permeability tests. In addition to the geotechnical testing, physical properties of the synthetic clay were examined and results from the geotechnical testing are presented in conjunction with the physical properties and sample preparation methods. Results of the geotechnical laboratory tests demonstrate that the synthetic clay exhibits macroscopic geotechnical properties comparable to soft cohesive soils and therefore can be used as a soft clay surrogate for use in geotechnical physical model testing, particularly those related to offshore geotechnics.