Feasability of using shredded tyres as a drainage material in geotechnical applications

Worldwide there are at least 1.6 billion scrap tyres produced each year. Of these Britain is responsible for 50 million, equating to an annual production of 700,000 tonnes of waste. Tyres have traditionally been disposed of in landfill sites and illegal dumping has caused problems. As a result many countries have implemented legislation and set objectives to reduce, and in some cases eliminate, the dumping and land-filling of waste tyres, EU legislation bans the disposal of whole tyres in landfill this month, and that of shredded tyres by 2006. To meet these requirements alternative uses of scrap tyres must be developed. Currently the most common of these are re-treading, burning for electricity generation/incineration in cement kilns and for surfacing for sports arenas and play areas. In the construction industry the tyres are shredded and used as lightweight fill, landfill drainage layers and as an alternative to aggregate in concrete and road pavements. Another option is to use the shredded tyres as a drainage material. Shredded tyres are a lightweight material which can be graded to suit requirements, are free-draining and very permeable. Under load the shredded tyres behave in an elastic manner and are highly compressible. Shear strength parameters are similar to those of a granular soil. Permeability reduces when loaded but remains higher than that of many other granular drainage materials. In light of these findings it is considered that shredded tyres could be used as a drainage material in many types of construction project and could in some circumstances be a viable alternative to aggregates or geotextiles. There are at present certain cases where traditional drainage materials are better to use but with further research to thoroughly establish the properties and behaviour of this new material, shredded tyres could be used with greater confidence in a widespread range of drainage applications.