Waste Tyre Recycling: potential applications with a focus on permeable pavements

Abstract

Increasing urbanization and development of automobile industry have given rise to an increase in global tyre waste generation. In Australia, it is estimated that around 450,000 tonnes of tyres reach their end-of-life annually and a large percentage of it is disposed to landfill or on-site burial or is stockpiled. This poses a significant environmental and safety risk, since such sites act as a breeding ground for pests and present a significant fire hazard. Hence it is essential to increase the recycling of this hazardous waste. This paper presents a review of the recycling of end-of-life tyres (EOLT) in Australia to produce tyre-derived products (TDPs), which traditionally has been based on mechanical recycling methods (using a series of shredders, screens, and granulators). Key TDPs from Australian tyre recovery include shredded tyres, crumb rubber and baled tyres. There is currently an emerging market in Australia for chemical recycling of tyres, which are typically based on pyrolysis and gasification processes. The produced TDPs have a variety of applications, with key most productive markets being that for crumb rubber in road sprayed seals and rubber granules in soft-fall surfaces and rubber matting in playgrounds and so on. There is a strong emerging market for rubberized concrete, which can be used as lightweight fill and as a drainage medium in landfills. New processing technologies like tyre pyrolysis to generate oil and tyre-derived fuel and also strongly emerging technologies. With a strong push for sustainable design initiatives, TDPs are also being used in permeable pavements, a water sensitive design strategy that is gaining popularity in Australia.