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Recycling asphalt conserves valuable resources and makes road construction more sustainable. Cold recycling is particularly low-emission and efficient. At STRABAG, we are already using this efficient road rehabilitation method in several countries - and want to use it more widely in German-speaking countries too.
What is cold recycling?
Cold recycling is an environmentally friendly and cost-effective method of road renovation. In contrast to conventional asphalt rehabilitation, old asphalt is recycled directly on site or in a nearby mobile mixing plant without heating. To do this, the construction team removes the damaged road surface with milling machines, granulates the material, prepares it with a bituminous binder and then reinstalls it.
In situ and in plant: two ways to sustainable road rehabilitation
The conditions on site determine which cold recycling method is used:
In situ: all work steps – milling, mixing and rolling – are carried out directly on the construction site in a single work process using the cold recycler.
In plan: the milled material is processed in a nearby mixing plant and then transported back to the construction site.
For projects with high quality and logistics requirements, such as motorways and expressways, the in-plant method is generally used. With the mobile mixing plant, the composition of the material can be precisely controlled and monitored, and asphalt transport can be planned with pinpoint accuracy. The in situ method, on the other hand, is suitable for smaller projects as well as country roads and side roads. The advantage here is that the road does not have to be completely closed, which enables faster and more flexible renovation.
Advantages of the cold mixing process: emissions down, cost-effectiveness up
Unlike asphalt production or traditional recycling, which require high temperatures for processing, the cold mixing process does not require the material to be heated. Instead, binders such as bitumen emulsion or foamed bitumen ensure that all components adhere well to each other. This reduces energy consumption enormously.
The old road surface can be completely reused. This not only significantly minimises the need for new raw materials such as rock and bitumen, but also reduces the amount of transport required to bring the material to the construction site and landfill.
Compared to conventional asphalt paving, the process reduces the carbon footprint by more than half. At the same time, the construction method provides an answer to the question of how the federal government and local authorities can renovate road infrastructure in a particularly economical way.
Repairing damaged roads is often time-consuming and costly. With cold recycling, we can significantly reduce both construction time and costs. And what is even more important: the process saves a great deal of CO2.
Project: The A6 motorway in Croatia
In countries such as Czechia, Slovakia and Croatia, cold recycling has long proven itself as an alternative to conventional construction methods. On the A6 motorway in north-eastern Croatia, STRABAG is rehabilitating a ten-kilometre section of motorway using the cold recycling- process. The STRABAG team has been working for the Croatian motorway company Hrvatske autoceste d.o.o. (HAC) since September 2025. Damir Pocrnja's team is recycling all of the approximately 13,000 tonnes of material produced. The mixing plant installed specifically for the project is located in the immediate vicinity of the construction site. This eliminates the need for many transports – for example, to the landfill site, which is about three times as far away. Cold recycling eliminates the need for almost 400 truckloads simply because no additional aggregates need to be delivered for road stabilisation.
TPA (Gesellschaft für Qualitätssicherung und Innovation) ensures that the road surface is in no way inferior in quality to conventional asphalt paving. Before construction began, its experts took asphalt material from the road, analysed it and adjusted the recipe for recycling to the material properties. After paving, TPA also monitors the load-bearing capacity of the renewed section.
Cold recycling in German-speaking countries: time for new standards
At STRABAG, we are committed to promoting the increased use of cold recycling in German-speaking countries. The challenge: to date, there are no industry-wide standards or binding regulations for the process. We are therefore also actively involved in committees, including the Road and Transportation Research Association (FGSV), and are specifically seeking partnerships to bring cold recycling to the roads.
