Paving the way for more asphalt recycling
Tests with recycled asphalt on Swiss roads show promising results. In Uster, canton Zurich, and on the Lukmanier Pass in canton Graubünden, the proportion of recycled asphalt could be increased without any loss of performance, it was announced on Thursday.
With a joint project of the Swiss Federal Laboratories for Materials Science and Technology (EMPA), the Federal Roads Office (ASTRA), the Federal Office for the Environment (BAFU), the cantons of Zurich and Graubünden and several industry partners, the researchers said they aimed to increase the proportion of recycled asphalt in roads.
Until now, much more asphalt waste has been produced in Switzerland than can be reused, EMPA said. Every year, 750,000 tonnes of asphalt from the Swiss road network end up in landfills.
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One obstacle to more asphalt recycling has been that the binder in asphalt ages and becomes stiff over time. This leads to a susceptibility to cracking. In addition, the material is sometimes very heterogeneous.
The EMPA researchers have therefore developed calculation models that can be used to calculate the perfect mixture for a specific application. With one model, the permissible variability can be calculated depending on future use. Another model calculates the dosage of the rejuvenating agents to be added. These are oily substances that soften the old binder in the reclaimed asphalt and thus make it usable again.
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Heavily trafficked and climatically difficult
On the Aathalstrasse in Uster, 30% recycled asphalt was added to the surface course. Typically, recycled material is not used in the surface course of such a heavily trafficked road, according to EMPA. Nevertheless, there were no cracks.
On the stretch over the Lukmanier Pass, the climatic conditions are considered difficult for the use of recycled asphalt. In EMPA’s report, however, the material proved resistant to cracking despite temperature fluctuations.
Over the next two years, however, the two test stretches will continue to be monitored, EMPA wrote.
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