Response of gravel-rubber mixtures under direct shear testing: experimental and DEM numerical investigation

Abstract

This paper presents the results from direct shear testing of gravel-rubber mixtures through laboratory experiments and numerical simulations with discrete element method (DEM). Mixtures with volumetric proportions of 0%, 10%, 25%, 40% and 100% granulated rubber were tested using a conventional, mediumsized direct shear apparatus under three normal stresses: 30, 60 and 100 kPa. Experimental results show a decrease in shear strength, greater strain at peak shear stress and less dilative behaviour with increasing rubber content. A selection of experimental results were used to calibrate the DEM model to examine the macro- and micro-responses of the mixtures. Good agreement was attained between the simulation and laboratory results under different normal stresses. This simulation exercise demonstrates that DEM is a suitable tool to describe the mechanical behaviour of mixtures made of hard-gravel and soft-rubber particles under direct shear loads without overly complex input parameters.