Stress-dilatancy behaviour of a polymer-coated sand

Abstract

Natural sands can be coated by substances of various origins, from natural to anthropogenic substances (from contamination or synthesized). Therefore, predicting the mechanical behaviour of coated sands is of practical significance and merits further research. Prior studies related to polymer coatings have shown a distinct hydraulic and mechanical behaviour for coated sands with the presence of the coatings significantly smoothening particle surface. This leads to a critical research question that is whether commonly used approaches, such as critical state soil mechanics and which was developed for natural (uncoated) sands, can be extended to coated sands. In this study, the stress-dilatancy behaviour of a sand coated with a polymer (polydimethylsiloxane) was investigated by means of triaxial compression tests in uncoated (natural) and coated conditions (thin versus thick coatings). Testing on the coated sands revealed a state-dependent behaviour similar to that of natural sands. Furthermore, relationships could also be established between the (1) initial state parameter and strength, (2) initial state parameter and dilatancy, and (3) dilatancy and strength of the coated sands. These results and methodology followed provide a basis for future studies on coated granular materials.