Empa repurposes old asphalt


Dübendorf ZH – The Swiss Federal Laboratories for Materials Testing and Research (Empa) has investigated the recyclability of old asphalt from landfills in road construction. Tests in Uster ZH and on the Lukmanier Pass have shown that the waste material can be mixed in varying proportions without any problems.

In a research project, the Swiss Federal Laboratories for Materials Testing and Research investigated the possibilities for recycling asphalt deposited on waste heaps in new road construction and repair. According to a media release, researcher Martins Zaumanis’ goal in doing so was to increase the recycled content in asphalt. For this purpose, two test sections with recycled asphalt were set up in Uster ZH and on the Lukmanier Pass between the cantons of Graubünden and Ticino. The results are reportedly promising.

The research project is called HighRAP (Reclaimed Asphalt Pavement) and was carried out by Zaumanis together with the Federal Roads Office, the Federal Office for the Environment, the cantons of Zurich and Graubünden and several industry partners from 2019 to early 2023.

The tests showed that on the busy road near Uster, 30 percent RAP content could be introduced without any problems and without any loss of performance. “Typically today, for a road this busy, RAP is completely omitted in the surface course,” Zaumanis said. For the underlying binder course, between 40 and 50 percent RAP was possible.

The road section at the Lukmanier Pass is not exposed to heavy traffic, but to harsh climatic conditions. At an altitude of 1900 meters, the strong temperature fluctuations can cause cracks in the road surface. Nevertheless, RAP admixtures of 85 percent in the foundation layer and 70 percent in the overlying base and binder layers were possible. ce/gba