A new material has been developed for usage on train tracks as subballast layer and it incorporates rubber shreds from old tires. The mixture is a combination with crushed stone and it has already been applied with great effect in roadside embankments and asphalt mixtures. Its usage in the rail sector, however, is yet to be explored.

UPV technicians have already assessed the new material with tests along a section of the Almoraima-Algeciras ADIF line in Andalusia. Along with offering an outlet for recycling old tires, it has also shown some serious advantages when compared to traditional materials. For example, it provides good insulation for urban environments in close proximity to rail traffic, since it absorbs vibrations from passing trains. Also it offers higher resistance to abrasion and fragmentation of the crushed stone due to the addition of tire rubber in the mix.

Researcher at the university’s Institute of Transport and Territory (ITRAT) Pablo Martínez Fernández has explained: “There are multiple benefits to using this material. On the one side, it contributes to mitigating the vibrations caused by moving trains. But at the same time it opens up a new market for many of our quarries, particularly limestone quarries, as well as for tyre recycling companies. It revitalises both sectors, making better use of the available limestone, not normally fit for use as a sub-ballast because of its low resistance to fragmentation, and the rubber from used tyres”.

The team working on this project is currently designing and analyzing the new material with various concentrations of used tires in the mix, searching for the best composition.

“From our laboratories at the Departamento de Ingeniería del Terreno (DIT) we analysed the response of the new material, with different concentrations of used tyre rubber, in order to find the best composition”, said Carlos Hidalgo Signes, from UPV.

One more characteristic of the mixture is that it does not require any binding materials: “We simply mix the crushed stone with the waste rubber, which is what gives it its cushioning effect”, said Hidalgo Signes.

Article and image source: Phys.org