Researchers are calling for an end to the burning of old car tyres after a study found that the rubber, steel and textile fibres in them can be used in concrete to make buildings greener, tougher and more resistant to earthquakes.
Incinerating such high quality materials as used in tyres is a plainly wrong and by demonstrating that they can be reused for their original properties– Professor Kypros Pilakoutas, University of Sheffield
Recycled rubber will allow buildings and other structures to flex up to 10% per cent along their length, researchers found, 50 times more than structures made from conventional concrete.
And tyre wire, which is exceptionally strong, can be blended with other steel fibres to increase the flexural strength of concrete – saving on virgin materials and reducing energy input requirements by 97%.
These fibres are also much thinner than conventional steel fibres, which means there are more in the concrete, helping to control cracks at the micro level.
The EU-funded research led by experts at the University of Sheffield and Imperial College London, working in association with the European Tyre Recyclers Association, has demonstrated that all tyre components can be reused in concrete.
"Incinerating such high quality materials as used in tyres is a plainly wrong and by demonstrating that they can be reused for their original properties," said Professor Kypros Pilakoutas from the University of Sheffield’s Department of Civil and Structural Engineering. "We are hoping that the decision makers will take steps towards limiting incineration to materials that cannot be reused."
A third component, the textile polymer fibres, used primarily as reinforcement in passenger tyres, is also of high quality and strength and can be used to control cracking at the early stages of concrete curing, when the material is still plastic.Â
Textiles fibres have also been shown by the Sheffield team to help prevent explosive concrete spalling (crumbling, breaking up) during fires, and applications are being developed for tunnels and buildings.
Plans are now being made to use the new concrete material in seismic resistant buildings, vibration isolation and bridge bearings. As part of the EU-funded Anagennisi project, demonstration projects will be undertaken in several countries to convince contractors and infrastructure owners of the benefits.
Tyres comprise roughly 80% rubber, reinforced with 15% steel and 5% textile fibre reinforcement.
Each year in the EU, more than 3 million tons of tyres reach the end of their lives.
Currently, most of Europe’s post-consumer tyres are incinerated despite environmental concerns and the fact that three-to-five times more energy goes into producing the tyre than is recovered.
"These high quality materials have valuable properties and deserve to be reused," said Professor Peter Waldron, MD of Twincon, a company that participated in the research.
The first processing facility for tyre wire has now been established in the UK by Twincon, as part of another EU Eco-innovation project which works in parallel to Anagennisi.Â
The research will be presented at a special dissemination event at Imperial College London on July 6.Â For further information visit: www.anagennisi.org
Photograph: Tyres comprise roughly 80% rubber, reinforced with 15% steel and 5% textile fibre reinforcement, and each year in the EU more than 3 million tons of tyres reach the end of their lives (Courtesy of Ichemeblog.org)