The EU-funded Anagennisi project, led by experts from the University’s Department of Civil Engineering, has demonstrated that rubber, steel and textile fibres extracted from used tyres can be recycled in concrete to make infrastructure greener, tougher and more resistant to extreme events.
Each year in the EU, more than 3 million tonnes 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.
Recycled rubber can replace mineral aggregates in concrete and allow buildings and other structures to flex up to 8 per cent along their length – 40 times more than structures made from conventional concrete.
Tyre steel wire is exceptionally strong and if blended with manufactured steel fibres increases the flexural capacity of concrete – saving on virgin materials and reducing energy input requirements by up to 97%. Being much thinner than manufactured steel fibres, these fibres also help control cracks more efficiently.
Anagennisi has led to the development of three new materials with unique properties that will enable engineers to re-think how they solve problems in a range of applications. Incinerating such high-quality materials as used in tyres is 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.
Professor Kypros Pilakoutas
Project coordinator
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. Textile fibres have also been found to prevent explosive concrete spalling (crumbling, breaking up) during fire.
Currently, most of Europe’s post-consumer tyres are incinerated or co-incinerated, despite environmental concerns and the fact that three to five times more energy goes into producing the tyre than is recovered.
The research is of interest to engineers, architects, contractors, designers, concrete manufacturers, material suppliers, specifiers and researchers, and the next stage is to exploit the new concrete materials in various structural applications such as seismic resistant buildings (vibration isolation and bridge bearings), industrial flooring or tunnel linings.
As part of the project, demonstration projects have already been undertaken in various European countries to convince contractors and infrastructure owners of the benefits.
These highly engineered materials have valuable properties and deserve to be recycled.
Professor Peter Waldron, MD
Twincon Ltd.
In particular, two full-size industrial concrete floors were successfully cast in Bosnia-Herzegovina and the Netherlands using recycled tyre steel wire as reinforcement. Both slabs were monitored for several months to assess their behaviour over time.
A series of shaking table tests were also conducted in Romania (Technical University of Iasi) using rubber in concrete proving that seismic resistance can be enhanced by 500% compared to conventional concrete. In Spain, tunnel linings were sprayed and concrete railway sleepers were prefabricated using recycled tyre steel fibres.
About the Anagennisi project
The three and a half year Anagennisi project (www.anagennisi.org) which ran from January 2014 to end June 2017 draws on expertise from seven European countries. The consortium comprises of five universities, a large construction company, a recycling association and six SMEs:
- The University of Sheffield (UK)
- Imperial College London (UK)
- Twincon Ltd (UK)
- University of Zagreb, Faculty of Civil Engineering (Croatia)
- Arkada Ltd (Croatia)
- Gradmont Ltd (Bosnia & Herzegovina)
- DULEX Ltd (Croatia)
- Gumiimpex - GRP Ltd (Croatia)
- Technical University ‘Gheorghe Asachi’ Iasi (Romania)
- Cyprus University of Technology (Cyprus)
- European Tyre Recycling Association (France)
- COMSA, S.A.U. (Spain)
- Fhecor Ingenieros Consultores, S.L. (Spain)