Particle–scale interactions and energy dissipation mechanisms in sand–rubber mixtures

Sand−rubber mixture (SRm) behaviour is affected by rubber content (RC) while dissipation in sands is caused by inter-particle sliding. Dissipation in SRm is as, or more significant than in sands. However, the mechanisms of dissipation in SRm are not well understood. In this study, one-dimensional compression tests on sand samples with RC of 0, 15, 30, 45 and 100% by mass were performed on a standard oedometer. In addition, a SRm with RC of 30% was tested on a mini-oedometer placed inside an X-ray scanner and three-dimensional images of the internal structure of the material were acquired at three stages during loading and unloading. Image analysis was used to infer particle-scale measurements and provide experimental evidence to help explaining the energy dissipation mechanisms for SRm. It is postulated here that energy dissipation in these mixtures is dominated by inter-particle sliding at initial stages of loading, but once rubber particles fill the void spaces between the sand, deformation and dissipation mechanisms are dominated by the deformation of the rubber particles.