Resource-saving road renovation on the A1

Photo of the A1, an asphalt recycling project on the Westautobahn

Asphalt recycling project on the Westautobahn in Austria

Road rehabilitation with asphalt recycling proves that "used" does not mean "old" or "bad". With this process, STRABAG conserves important resources such as bitumen and rock. That's why we want to put more used asphalt on the road. On the A1 Westautobahn at the Steinhäusl junction in Austria, we have even worked with a significantly higher recycling rate than usual when renovating roads. This is made possible by a good partnership with the client and our asphalt mixing plants, some of which are ultra-modern.

The asphalt recycling project shows that road rehabilitation with the addition of recycled asphalt is not only sustainable, but also possible without compromising quality: with 74,000 vehicles per day, including many trucks, the A1 is a busy highway.

Photo of an asphalt mixing plant in Hausleiten

How does sustainable road rehabilitation work on the A1?

More environmentally friendly road rehabilitation can be achieved through higher recycling rates in the asphalt mix. In some projects, it is already possible to use an above-average amount of recycled material with the consent of the client.

In order to achieve an even higher recycling rate, everyone must pull together - both the planners and the tenderers. In addition, the standards, laws and requirements must be adapted accordingly.

Axel Thomaschütz
Member of the Executive Board STRABAG AG Austria

STRABAG has renewed an eight-kilometer stretch of freeway on the A1 for ASFINAG in several sections. We used an asphalt mixture in the base course that consists of 40 percent recycled milled material. As part of the heavily used road network, only 20 percent is usual on freeways in Austria. In the binder course above this, 20 percent recycled material is used and only new material is used in the surface course.

Of course, we are not throwing away the old asphalt demolition waste from the Westautobahn - this will also be reprocessed and used in another road renovation project.

Graphic of the different asphalt layers: surface course, binder course, base course

High-quality asphalt from the surface course is usually reused in the binder or base course and is therefore unfortunately downcycled.

A higher proportion of used asphalt saves important resources in road rehabilitation. The asphalt mix used on the A1 comes from our advanced asphalt mixing plant in Hausleiten. It is one of the most modern in Austria. In purely technical terms, it could produce asphalt mix from 100 percent used asphalt.

More asphalt mixing plants of this kind are needed in Austria in order to produce mixes with a particularly high recycling rate throughout the country in the future.

How do we guarantee quality in our asphalt recycling projects?

Recycling reduces the need for stone and bitumen. The asphalt recycling project on the A1 shows two things. 2Firstly, the reuse of asphalt can conserve important resources and save CO emissions. Secondly, recycling reduces the cost of purchasing raw materials. Bitumen in particular is a fossil raw material that should be avoided in the interests of environmental protection. It is also expensive and chemical processing to make hardened bitumen liquid again is significantly cheaper.

On the A1, STRABAG was able to carry out the contract for ASFINAG at a lower price while maintaining the same quality. The tests on the mix with 40 percent recycled content were carried out by the TPA (Gesellschaft für Qualitätssicherung und Innovation) team in their laboratory in Trumau. This enables us to ensure the quality of the highway.

In purely qualitative terms, even higher rates of road rehabilitation would be possible. However, there is a lack of important empirical data, for example on the question of how asphalt quality develops over the years of road use. Asphalt pavements with recycled content are generally subject to strict quality controls, which are carried out on a close-meshed basis and for a longer period of time after paving. For example, the skid resistance of the pavement and the strength of the layers are tested. In the event of defects such as cracks in the asphalt or rutting, the construction company must repair or even replace entire layers.

How can road renovations in Austria become even more sustainable?

The STRABAG team used around 94,000 tons of recycled material on the A1 out of a total of 114,000 tons of asphalt mix. Of this, 24,800 tons are pure old asphalt. The asphalt recycling project shows that STRABAG can carry out road renovations with used asphalt of the same quality as usual. One approach to increasing the use of used asphalt would be to use it more in the base course. This is because it does not have to meet the same requirements as the surface course. For our colleagues on the construction site, using recycled materials makes no difference.

Everyone must pull together to achieve this: The clients, the planners, the construction companies and the politicians. We need strong partnerships, such as with ASFINAG, to further promote asphalt recycling and make road renovations more sustainable.

The difference between new and recycled asphalt mix is not visible to the naked eye.

Factsheet:

A1 Sustainable road renovation

pdf ∙ 16 MB