Material recovery and recycling of waste tyres-A review

The largest consumer of natural and synthetic rubbers around the world is the tyre manufacturing industry. The recycling and disposal of end-of-life tyres (ELTs) are major challenges in waste management due to its complex structure and composition. The crosslinked 3D structure of rubber resulting from vulcanisation along with stabilisers and additives incorporated during manufacture also make tyres resistant to natural degradation. Because of this, a large proportion of ELTs end up in landfill where those become serious threats to the environment. Fortunately, useful materials can be recovered from ELTs via various recycling routes. The recovery of ground tyre rubber (GTR) using the ambient, cryogenic, and other processes was critically review in this paper. It is found that, recycled rubber aggregates can be used directly as fillers and modifiers in the production rubberised asphalt and concrete. Additionally, GTR can be further processed through mechanisms such as chemical, mechanochemical, microwave, ultrasound, and microbial devulcanization to improve its usability in the abovementioned processes. The recovery of energy, oils, solids, and gaseous products from the combustion or pyrolysis of ELTs is another beneficial recycling approach. It is suggested that this approach does not take full advantage of the useful properties of vulcanised rubber. Furthermore, the feasibility of such methods depends on the market available and acceptance of tyre derived diesels as alternate fuels.