According to WPB, a German research project developing asphalt without additional fossil-based bitumen has moved from laboratory testing to a real road trial in Braunschweig, Germany. The experimental pavement incorporates 60% reclaimed asphalt and a pine-derived bio-based material, marking an important step toward reducing dependence on newly produced petroleum bitumen in road construction. However, the field mixture still contains a small proportion of fresh fossil-based bitumen, highlighting the technical challenges of transferring laboratory innovations into commercial asphalt production.
The development was announced on October 26, 2026, by the Technical University of Braunschweig. The research is part of NOBIT (No Bitumen), a collaborative project involving TU Braunschweig, TU Wien in Austria, and OST – Eastern Switzerland University of Applied Sciences. Supported by the Volkswagen Foundation, the initiative aims to develop asphalt using up to 100% reclaimed materials without adding fresh fossil-derived binders.
Under the laboratory concept, researchers combine processed reclaimed asphalt with bio-based additives, including oils and resins derived from the paper and pulp industry. The objective is to restore the performance of aged asphalt binder while minimizing the need for newly produced petroleum materials. According to the research team, laboratory testing has demonstrated material behavior comparable to conventional asphalt containing fossil-based binder, providing the technical basis for moving toward field evaluation.
The first practical trial has now been incorporated into a road rehabilitation project on Berliner Straße, a major road in Braunschweig. The broader reconstruction covers approximately 600 meters between Querumer Straße and Friedrich-Voigtländer-Straße, where the existing asphalt surface and binder layers are being replaced. Within this project, researchers have established a dedicated experimental section covering approximately 1,100 square meters, using around 220 metric tons of the newly developed asphalt mixture.
Unlike the laboratory formulation, the road-tested mixture consists of 60% reclaimed asphalt combined with distilled tall oil derived from pinewood and a small amount of fresh petroleum-based bitumen. Tall oil is a bio-based material associated with wood processing and the pulp industry, making it a potential alternative or supplementary component in asphalt binder formulations.
The decision to retain some fresh fossil bitumen in the field mixture reflects practical limitations at regional asphalt mixing plants. Existing production equipment and processing capabilities have not yet allowed the researchers to implement the laboratory concept in its intended form without additional fresh fossil binder. The field trial therefore represents an intermediate step toward the project's ultimate objective rather than a demonstration of completely fossil-free asphalt production.
An important technical distinction is that the NOBIT concept targets the elimination of newly added fossil bitumen, not necessarily the complete removal of petroleum-derived material from the pavement. Reclaimed asphalt already contains aged bitumen from its previous service life. The research seeks to reuse that existing binder with bio-based additives instead of relying on additional virgin petroleum bitumen.
The Braunschweig project is also examining lower-temperature asphalt production. Alongside the bioasphalt research section, two other asphalt concepts incorporating different temperature-reducing additives are being tested in the binder layer. These technologies are intended to lower production and compaction temperatures by approximately 20°C, from around 160°C to 140°C.
Lower processing temperatures could reduce energy consumption and occupational exposure to bitumen fumes and aerosols. The temperature-reduction work is also relevant to updated German road construction requirements introduced in 2026 following changes to workplace exposure limits. However, the reported temperature reduction should not be attributed exclusively to the pine-derived bioasphalt formulation, as the project evaluates separate asphalt concepts.
Researchers from TU Braunschweig are collecting samples of freshly delivered asphalt and conducting laboratory tests, including evaluations of resistance to low-temperature cracking. Meanwhile, scientists from TU Wien's Institute of Materials Chemistry are conducting an emissions assessment designed to compare the three experimental road sections. These measurements will help determine how the different materials and production methods perform under construction conditions.
For the bitumen industry, the project is particularly relevant because it addresses one of the main barriers to high-content asphalt recycling: the need to compensate for the increased stiffness and aging of reclaimed binder. Conventional asphalt recycling frequently requires additional fresh bitumen to maintain satisfactory mechanical performance. Bio-based additives could potentially reduce that requirement, provided the resulting mixtures continue to meet durability, cracking resistance, and other engineering specifications.
The project also illustrates the importance of distinguishing laboratory performance from industrial readiness. Although the experimental bioasphalt has demonstrated promising mechanical characteristics, its long-term behavior under actual traffic, weather fluctuations, repeated loading, and aging remains under evaluation. The field trial does not yet establish that the new material will match conventional asphalt over its full service life.
From a commercial perspective, successful development could create opportunities for suppliers of bio-based asphalt additives and companies processing reclaimed asphalt. It may also gradually reduce the quantity of fresh petroleum bitumen required for selected pavement applications. Nevertheless, the extent of any future market substitution will depend on industrial processing capabilities, material availability, performance requirements, production economics, and environmental assessments.
The NOBIT project runs through January 31, 2027, and additional experimental road sections are already being prepared. Its next phase will be particularly important in determining whether the promising laboratory results can be translated into reliable, scalable road construction technology.
For petroleum refiners, bitumen producers, and asphalt manufacturers, the central development is not that fossil-based bitumen has already been eliminated from road construction. Rather, the German trial shows that highly recycled asphalt combined with renewable binder components has progressed into real-world testing, bringing the industry one step closer to reducing its dependence on newly produced fossil-based bitumen.
By WPB
Germany Bioasphalt, NOBIT Project, Bio-Based Binder, Reclaimed Asphalt Pavement, RAP 60%, Tall Oil, Pine-Derived Binder, Fossil Bitumen Replacement, TU Braunschweig, TU Wien, Asphalt Recycling, Low-Temperature Asphalt, Sustainable Road Construction, Bitumen Technology
