Paving the way for more asphalt recycling
When roads are repaired, patched and renewed in Switzerland, some of the old asphalt is recycled, some of the old asphalt from the Swiss road network is being recycled, but around 750,000 tons end up in landfills every year, piling up into ever higher black mountains. In principle, these asphalt mountains should be put back into the Swiss roads. However, Switzerland is so well developed that hardly any new roads are being built.
It is thus all the more important that the proportion of recycled asphalt is as high as possible whenever repairs, patching and renewals are carried out. It is thus all the more important that the proportion of recycled asphalt is as high as possible whenever repairs, patching and renewals are carried out. “But this requires a better understanding of the interaction between reclaimed asphalt and new material, adapted production processes and – above all – practical instructions and tools for the industry,” says Empa researcher Martins Zaumanis. These are precisely the goals of a recent esearch project.
Without any loss of performance
The production of asphalt with reclaimed asphalt pavement (RAP) is significantly more complex than the production of new asphalt due to the large number of different materials and substances that are mixed together. For this reason, HighRAP asphalt has been installed on two road sections as part of his project – on the busy Aathalstrasse in Uster on the one hand, and on the Lukmanierpassstrasse on the other, where the requirements for the road surface are significantly different due to the high altitude.
In Uster, a RAP content of 30% could easily be introduced in the wearing course without any loss of performance. In contrast to the road in Uster, the route over the Lukmanier Pass is not exposed to heavy traffic, but to harsher climatic conditions. “At this altitude of 1900 meters, the high temperature fluctuations can cause cracks in the road surface,” says Zaumanis. But in his project, he showed that an asphalt with a high RAP content could also withstand these conditions. An asphalt with 85% RAP content was paved in the foundation layer and an asphalt with 70 % RAP content in the base and binder layers above: without any problems!
Further information can be found on the Empa website.