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Plastic recovery technology: a new more durable and sustainable asphalt

The new asphalt, which uses end of use tyres and caps, package and hanger wastes for modifying mixes, has been used to pave a 2-km long M-300 section road at access points to Alcalá de Henares (Madrid) in which the good performance of asphalt mixes using polymer waste has been checked.

AIMPLAS collaborating with the company Acciona Infraestructuras, the Road General Directorate of Madrid Community and coordinated by University of Cantabria, has secured a new more durable and sustainable asphalt mixes due to the incorporation of plastic waste to this mixture.

This asphalt is made by, apart from the original wastes, end of use tyres, polypropylene (mainly) caps, polyethylene packages and polystyrene hangers to pave a 2-km long M-300 section road at access points to Alcalá de Henares (Madrid). After studying the performance of the asphalted section road over the last 18 months, POLYMIX project’s partners have concluded that new asphalt mixes comply with the requirements established in the technical specifications to build roads and that mixes including polymeric wastes in their compositions are more resistant to plastic deformation than the traditional mixes. This allows mixes perform much better when cracks appear, especially with high temperatures and slow moving traffic Moreover, a generalized increased rigidity is produced without compromising or even improving the fatigue behavior of the mixes, as in the case of end of use tyres. These mechanical properties convert POLYMIX mixes in a rolling layer which carries a higher traffic load and improves the structural capacity of pavement.

Results of the rolling test

It can be seen how Polymix mixes significantly increase resistance to plastic deformation, in contrast to the reference one. In the case of PP, it practically doubles the result. All the polymeric materials tested show very good results in the technical and economic viability study. It is important to highlight that in the case of end of use tyres and polypropylene, it has been proved that thanks to these components, the mixes can be manufactured with lower thicknesses due to their improved properties. This is why cost of production is reduced. Environmental and economic advantages The use of alternative asphalt, as the one developed in the POLYMIX project, has several advantages both for the environment and economy. On the one hand, the volume of raw materials used in its manufacturing can be reduced, such as natural aggregates; on the other hand new ways to recycle large volumes of plastic waste are provided using a simple method which can be incorporated in any asphalt. So if it is established all over the country, wastes could be practically consumed when they are generated. Indeed, the life cycle analysis carried out prove that due to the incorporation of polymeric wastes we can obtain more sustainable roads with less environmental impact.

The results of POLYMIX project (LIFE10 ENV/ES/000516), financed by European Funds through the Life+ Program, have been proved with series of monitoring tests carried out by CEDEX (Centro de Experimentación de Obras Públicas), of Ministerio de Fomento.