Geotechnical Characterization of Laponite as Transparent Clay Surrogate

Abstract

The use of so-called “transparent soils” as proxy geotechnical materials has allowed for the nonintrusive observation of a variety of models representing different engineered systems. Laponite is one such soft clay surrogate that has seen increased usage in recent years. However, this material has yet to be subjected to a thorough characterization and quantification of its physical and mechanical properties. The study presented herein followed a systematic approach toward the characterization of Laponite RD colloids from a geotechnical perspective across a wide range of mixes and additive dosages. Rheology tests were conducted to study the variation in apparent viscosity with time and after remixing. These tests identified two sources/types of strength gain: a reversible thixotropic strength gain and an irreversible particle aggregation strength gain. Different mixtures tested in a one-dimensional consolidation oedometer showed that mixes with laponite colloid contents as high as 21 % could be achieved from mixes with an initial colloid content of 11 % by mass. Finally, results from vane shear tests showed that the undrained shear strength increased with: (1) increasing laponite colloid content, (2) decreasing additive dosage, (3) aging time, and (4) increasing temperature. The base geotechnical characteristics and mechanical properties of the clay surrogate as provided in this study are expected to facilitate proper interpretation of the behavior of this surrogate material in geotechnical physical models involving transparent clays. © 2023 ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959.