Advanced geotechnical solutions for sustainable transportation infrastructure using waste materials

In view of worldwide national policies embracing the socio-economic and environmental perspectives of a circular economy, the Transport Research Centre at the University of Technology Sydney (UTS-TRC) has launched innovative measures of trialling recycled rubber derivatives in sustainable and innovative design of load-bearing substructure for railways in collaboration with industry. In this regard, this paper critically reviews two novel applications of recycled materials: (i) rubber intermixed ballast stratum (RIBS) to replace conventional rockfill, (ii) a hybrid track using recycled rubber tyre cells infilled with waste granular mixtures as an energy absorbing layer (REAL) which also provides additional confinement to the track substructure. Comprehensive laboratory tests using prototype cyclic triaxial testing rigs, the National Facility for High-speed Rail (NFHSR), and field tests have been conducted to examine the performance of these rubber inclusions. The tangible outcomes of laboratory and field tests reveal that the recycled rubber inclusions can act as energy reservoirs, thereby alleviating ballast breakage, deformation, and track acceleration, thus increasing the track stability.