According to WPB, a new European research project has officially begun examining whether bio-based binders can be combined with reclaimed asphalt to increase recycling rates in road pavements without sacrificing engineering performance. The BRAVE project started on October 1, 2026 and will run until September 30, 2028, focusing on the chemical, rheological and ageing behaviour that develops when binders containing biogenic components interact with aged binder recovered from recycled asphalt.
The project’s full title, “Towards sustainable asphalt pavements by utilising Bio-binders in Recycled Asphalt Via chEmomechanics,” reflects its central technical question. Rather than studying bio-based binders in isolation, BRAVE will investigate how they behave when combined with reclaimed asphalt, where the existing binder has already undergone production, service-life and environmental ageing. The aim is to identify recycling strategies that can increase the amount of reused asphalt material while maintaining acceptable pavement performance.
The project is coordinated by Aristotle University of Thessaloniki in Greece, with Vienna University of Technology and Swedish bitumen producer Nynas participating as partner organisations. The European Union contribution recorded for the project is approximately €181,424, and the research is being carried out through a Horizon Europe postdoctoral fellowship led by Dr. Georgios Pipintakos.
This structure is important when assessing the scale of the development. BRAVE is a focused research project rather than a commercial-scale bio-binder production programme or a full road-demonstration deployment. Its immediate objective is to build a stronger scientific basis for combining bio-based binders with reclaimed asphalt and to determine whether repeated recycling can be achieved without creating unacceptable durability or performance losses.
That distinction also separates BRAVE from projects focused primarily on producing bio-bitumen from waste streams. In those projects, the principal technological challenge is converting biological or organic feedstock into a binder capable of replacing part or all of petroleum-derived bitumen. BRAVE begins at a different stage by examining what happens when a bio-based binder is introduced into a recycled asphalt system containing already-aged bituminous material.
Reclaimed asphalt presents a particular materials challenge because the binder recovered from an old pavement is generally stiffer and more aged than virgin binder. Oxidation and loss of lighter components during production and service can increase stiffness and reduce flexibility, meaning that simply increasing the percentage of reclaimed asphalt can increase susceptibility to cracking if the blend is not properly designed.
Bio-based materials may provide one route for modifying those aged binder properties, but their effect cannot be assumed to be uniformly beneficial. Some bio-derived components can soften aged binder and improve low-temperature or fatigue behaviour, while excessive softening can reduce resistance to permanent deformation at higher temperatures. Long-term ageing can also behave differently depending on the chemical origin and composition of the bio-based material.
This is why BRAVE places particular emphasis on compatibility, ageing and durability rather than only on initial binder softness. The project is designed to study how the chemical characteristics of the bio-binder and the aged reclaimed binder interact and how those interactions influence rheological behaviour over repeated recycling cycles.
The project will use a chemomechanical approach that links changes in chemical composition with measurable mechanical and rheological behaviour. Thermogravimetric analysis will be used to examine thermal behaviour and material composition, while carbon nuclear magnetic resonance spectroscopy will provide information on chemical structures and molecular changes. Dynamic shear rheometer testing will then be used to quantify rheological response and relate those chemical characteristics to performance.
Advanced multivariate statistical methods will also be used to identify relationships among the different chemical and mechanical variables. This is significant because a single conventional binder test may not adequately explain why one bio-binder and reclaimed-binder combination performs differently from another.
The approach may also help address one of the persistent problems in recycled asphalt research: a blend can satisfy one performance indicator while creating weakness in another. A material that restores flexibility to heavily aged RAP binder may improve fatigue or cracking resistance but simultaneously reduce stiffness enough to increase rutting susceptibility under high-temperature loading.
The challenge becomes more complex after repeated recycling. A pavement containing reclaimed material may itself eventually be milled and reused again, meaning that its binder can pass through several cycles of heating, oxidation, blending and service ageing. BRAVE specifically identifies multiple recycling potential as one of the properties it intends to quantify.
That focus could become increasingly relevant as European road authorities seek to raise recycling rates. Using reclaimed asphalt once reduces demand for virgin aggregate and binder, but achieving a more circular pavement system requires materials that can remain technically usable over more than one recycling cycle.
Bio-based binders may contribute to this objective if they can restore or modify aged binder properties without creating unacceptable deterioration during subsequent ageing. However, current scientific literature shows that bio-based binders can vary substantially in composition and ageing response, meaning performance cannot be generalized across all biological feedstocks.
Recent research has highlighted ageing as one of the major unresolved questions in bio-based asphalt technology. Some bio-based binders contain lighter or oxygen-rich compounds that can make their behaviour under volatilisation and oxidation different from conventional petroleum bitumen, while other formulations have demonstrated favourable ageing characteristics. The outcome depends heavily on chemistry, dosage, processing conditions and the characteristics of the base binder.
The presence of reclaimed asphalt makes compatibility even more important because the new binder does not operate independently. It must interact with aged binder already coating the reclaimed aggregate, and the extent to which the old and new binder phases blend can influence stiffness, cracking resistance, deformation behaviour and durability.
BRAVE therefore has potential significance beyond simply replacing fossil-derived binder with a renewable component. Its larger technical question concerns whether bio-based chemistry can help make higher recycling rates technically viable while preserving the balance of pavement properties required during service.
The participation of Nynas gives the project a direct link to an established European bitumen producer, while the involvement of academic partners provides access to advanced chemical and rheological research capabilities. However, participation by an industrial bitumen producer should not be interpreted as evidence that a commercial BRAVE-derived binder has already been selected or is ready for market introduction.
The publicly available project information does not currently identify the biological feedstock that will be used to produce the bio-binder, the percentage of conventional bitumen it will replace, the exact reclaimed-asphalt content targeted in the mixtures or a specific commercial binder formulation. No full-scale road trial or commercial production target has yet been announced publicly.
This limitation is important because the term “bio-binder” covers a wide range of materials. Products can be derived from vegetable oils, lignocellulosic materials, agricultural residues, waste-derived bio-oils or other biogenic sources, and their chemical characteristics can differ substantially. Without the final formulation, no conclusion can yet be reached regarding carbon reduction, commercial cost, production scalability or exact pavement performance.
The same caution applies to the environmental benefits. Increasing reclaimed asphalt content can reduce demand for virgin aggregate and new binder, while replacing fossil-derived material with biogenic components can potentially lower dependence on petroleum resources. However, the actual environmental benefit depends on feedstock origin, processing energy, transportation, binder lifespan and the number of times the pavement can genuinely be recycled.
A binder that contains renewable material but causes premature pavement failure could lose part of its theoretical environmental advantage because additional maintenance and reconstruction would be required. BRAVE’s emphasis on durability and multiple recycling is therefore important because sustainability must be evaluated alongside service performance rather than through bio-based content alone.
The project also reflects a broader change in asphalt technology. Research is increasingly moving away from evaluating recycled content, bio-based content and pavement performance as separate objectives and toward studying how these variables interact within the same material system.
This is especially relevant for high-recycling strategies because aged binder becomes progressively more important as reclaimed asphalt content increases. The ability to understand and control the interaction between aged petroleum binder and newly added bio-based material could determine how far recycling rates can be increased without compromising the pavement.
If BRAVE can establish reliable relationships between chemical composition, ageing and mechanical behaviour, its results could support more targeted formulation of bio-based binders for recycled asphalt. Instead of treating a bio-binder merely as a generic softening agent, future formulations could potentially be selected according to the chemical condition of the reclaimed binder and the performance requirements of the pavement.
Such an approach could also improve quality control. Reclaimed asphalt is inherently variable because its binder composition and ageing history depend on the original pavement, climate, service period and previous maintenance. A chemomechanical framework could help explain that variability and support more systematic decisions about how much bio-based material should be added.
However, BRAVE remains at the research stage and should not yet be presented as evidence that bio-binders have solved the technical limitations of high-recycled asphalt. The project has only begun, and the compatibility, ageing resistance, repeated recycling potential and durability of the investigated materials still need to be demonstrated.
The most important results to watch over the next two years will be the type and composition of the selected bio-binders, their interaction with reclaimed binder, changes in rheological properties after ageing, behaviour through repeated recycling cycles and any evidence that higher reclaimed-asphalt content can be achieved without unacceptable losses in cracking or rutting performance.
Any subsequent mixture-scale or field validation would also be important. Binder-level chemistry and rheology can identify mechanisms and provide strong performance indicators, but long-term pavement behaviour ultimately depends on the complete asphalt mixture, including aggregate structure, air voids, moisture resistance, production temperature and field compaction.
For the bitumen industry, the significance of BRAVE lies in the possibility that future road-binder demand may increasingly be defined not simply by the volume of virgin bitumen required for a project but by how efficiently virgin, aged and renewable binder components can be combined. Higher recycling rates could reduce virgin binder requirements per ton of asphalt while simultaneously creating demand for more technically sophisticated binder formulations.
The project therefore should not be interpreted simply as another attempt to replace conventional bitumen. Its more important contribution may be to determine how bio-based binders can function inside a circular asphalt system in which reclaimed binder remains an active engineering component rather than being treated only as recycled waste.
BRAVE began on October 1 with that question still open. By September 2028, the project aims to provide a clearer scientific basis for determining whether bio-based binders can support higher asphalt recycling rates while maintaining compatibility, durability and mechanical performance through repeated ageing and recycling.
By WPB
BRAVE project, bio-binder, recycled asphalt, reclaimed asphalt, RAP, Horizon Europe, Nynas, asphalt recycling, sustainable asphalt, bitumen technology, binder chemomechanics, asphalt rheology, binder ageing, circular asphalt, road bitumen, bio-based binder, multiple recycling, pavement durability
