Study finds old tyres can be completely reused to make concrete

An EU-funded project led by experts at the University of Sheffield and Imperial College London, working in association with the European Tyre Recyclers Association, has demonstrated through extensive experimental work that all tyre components can be reused in concrete.

Results of this work will be presented at a special dissemination event at Imperial College London today. The event will be of interest to engineers, architects, contractors, designers, concrete manufacturers, material suppliers, specifiers and researchers.

Recycled rubber, for example, will allow buildings and other structures to flex up to 10 per cent along their length – 50 times more than structures made from conventional concrete.

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 per cent. 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.

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. 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.

Each year in the EU, more than 3 million tons of tyres reach the end of their lives. Tyres comprise roughly 80 per cent rubber, reinforced with 15 per cent steel and 5 per cent textile fibre reinforcement.

Professor Peter Waldron, MD of Twincon Ltd, argues: “These high quality materials have valuable properties and deserve to be reused.”

Currently, most of Europe’s post-consumer tyres are incinerated or co-incinerated, despite environmental concerns and the fact that 3-5 times more energy goes into producing the tyre than is recovered.

The first processing facility for tyre wire has now been established in the UK by project partner, Twincon Ltd, as part of another EU Eco-innovation project which works in parallel to Anagennisi. As currently demand outstrips supply, there are plans to scale the production up by setting up processing facilities at other recycling plants around Europe.

Professor Kypros Pilakoutas from the University’s Department of Civil and Structural Engineering, who coordinates the EU research project Anagennisi, said: “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, we are hoping that the decision makers will take steps towards limiting incineration to materials that cannot be reused.”