This paper presents a method to create rubber clumps without significant volume loss within the framework of the discrete-element method (DEM), enhancing the understanding of particle-scale stress transmission and small strain behavior of sand-rubber mixtures. Extensive calibrations were conducted, including the compressive response of individual pure rubber clumps, the small strain stiffness and the shear behavior of pure rubber specimens. These calibrations aimed to accurately capture the key characteristics of rubber materials, including their deformability. The calibrated model was then used to study the mechanics of sand-rubber mixtures. The simulation data indicated a higher coordination number for rubber clumps, a result of their greater deformability and significant sensitivity to stress levels in comparison with sand grains. The research has further demonstrated that the proportion of the overall stress transferred by the rubber remained below its volumetric content, highlighting its significant sensitivity to stress and density levels, which are characteristics not significant in sand particles. Additionally, the small strain stiffness values of sand-rubber mixtures decrease with increasing rubber contents, reflecting the negligible contributions of rubber materials on small-strain stiffness. This observation supports the validity of refined state variables that exclude rubber materials when characterizing the small-strain behavior of sand-rubber mixtures. While this research is fundamental, the data presented herein can be useful to engineers working on embedding waste materials such as granular rubber in engineered fill.

This research investigates the particle-scale stress transmission characteristics at the end of isotropic consolidation stage for sand-rubber mixtures, focusing on the effects of particle size disparity, density, and stress levels. The discrete element method was adopted with total 450 simulations being conducted for sand-rubber mixtures with increasing size disparities to quantify the particle-scale stress distribution between sand and rubber materials. This study reveals that the variation of coordination number and void ratio for sand-rubber mixtures align with those observed in conventional gap-graded soils, while the inclusion of deformable rubber clumps significantly increases coordination number values. A complex interplay between packing density and stress level was evident, illustrating the nuanced role of rubber in stress transmission. As packing density and stress levels decrease, the efficacy of deformable rubber clumps in stress transfer increases. An inverse relationship between the efficiency of stress transmission and particle size disparity was observed for all these sand-rubber mixtures. The findings indicate that, despite variations in size disparity, the proportion of stress transferred by rubber remains consistently lower than their volumetric contribution. This study underscores the complexities of using sand-rubber mixtures and highlights that the effect of particle property disparity outweighs the that of particle property disparity.