Rubber and polymer fibres from discarded car tyres could soon be used in major civil engineering projects such as bridges, tunnels and earthquake-resistant buildings, researchers believe.
The University of Sheffield led Anagennisi project team is working on trials to prove the viability of using the waste products in specialised concrete.
It believes the textile polymer fibre found in tyres can be used instead of polypropylene to control cracking in concrete and could be available to market within two years.
The project team is also trying to prove that tyre rubber can make concrete flexible enough to be an advantage in areas of seismic activity as well as in bridges. It hopes this product will be available by the end of this decade.
Anagennisi has credibility, having already worked on conversion of steel wire found in tyres into concrete that is being used commercially for floors of industrial buildings.
University of Sheffield engineering professor Kypros Pilakoutas told NCE the project was motivated by a desire to slash the volume of tyres being incinerated.
“All the steel from tyre recycling plants will end up in concrete,” he said.
“The same amounts of polymer fibres are produced in tyre waste as polypropylene is currently used concrete, so concrete could use all of that too.
“Rubber use would require quite a shift in concrete practice but it will open up another avenue.”
Pilakoutas said the waste tyre products would be financially attractive for use in concrete, as well as offering environmental benefits and allowing innovative designs.
“With the rubber, we use a Kevlar jacket around the concrete to ensure it doesn’t expand,” he said. “It becomes very flexible in the other direction but remains strong.
“It could be used in bridges instead of bearings and joints, as well as in seismic areas to allow buildings to flex.”
The rubber-infused concrete will be tested on a shaking table next year with the aim of getting it to market by 2020.
“With polymer fibre, we are doing experiments on restrained shrinkage, and fire tests,” said Pilakoutas.
“We hope to make demonstration projects next year, and then set up facilities to process and produce it. It could come to market within two to three years.”
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% according to the project team.
Peter Waldron, managing director of University of Sheffield spin-out Twincon, which supplies the tyre wire added concrete commercially, said: “These high quality materials have valuable properties and deserve to be reused.”