Shear and Deformation Behaviour of Rubber Sand Mixture Reinforced with Geogrids and Geocells

The global surge in automobile production due to industrialization has led to a significant increase in scrap tyre generation and disposal. The abundance of scrap tyres offers an opportunity to utilize them as rubber sand mixtures (RSM) for various purposes, including lightweight backfill, drainage, insulation, and seismic isolation. However, the utilization of RSM is constrained by its increased deformability, which ultimately results in the settlement of structures. This study aims to investigate the shear strength parameters and deformation behaviour of clean sand, RSM, and reinforced RSM using large-scale direct shear tests. RSM is prepared by mixing granulated rubber with sand in a 30% gravimetric proportion. Clean sand exhibits a peak shear stress followed by strain softening, typical of medium dense sand behaviour. In contrast, RSM demonstrates strain hardening, indicating ductile behaviour. RSM however exhibits six times compressibility compared to clean sand. The introduction of reinforcement in the form of geogrid and geocell at the middle layer of the shear box improves the performance of the RSM. Both geogrid and geocell-reinforced RSM develop apparent cohesion, with geocell reinforced RSM showing higher interface friction. The introduction of Geogrid reinforcement reduces the compressibility by 15% while geocell reinforcement results in 27% reduction in compressibility of RSM.