Project Summary
University of Nottingham will capitalise on recent advancements to develop environmentally friendly microalgae-based bio-binder that can be used in asphalt pavement applications to improve road performance, including durability. Road binders based on microalgae biomaterials will store carbon within the carriageway and reduce fumes released from conventional asphalt pavements during application. The use of novel biobased materials promises to greatly advance the transport sector’s carbon reduction aims by transitioning away from traditional binding materials such as crude oil-based bitumen.
Project Achievements
1. Optimised production: Established the pyrolysis window (425–600 °C, controlled heating rates, defined residence times) for Spirulina and Chlorella, maximising yields of microalgae-derived bio-oil and biochar and generating the parameter database for these feedstocks.
2. Material validation: Comprehensive physico-chemical and rheological testing showed that biochar added at 4–8 wt % as bitumen modifier can significantly improve high-temperature rutting resistance and it can also fully substitute traditional mineral fillers in asphalt mixtures.
3. Binder rejuvenation: Viscosity tuning plus thermal-oxidative ageing enabled bio-oil to function as an effective rejuvenator whose rheological and adhesive properties approach commercial high-penetration bitumen.
4. Technology readiness: Achieved TRL 4 by proving laboratory-scale feasibility of integrating both bio-products into asphalt materials.
5. Knowledge dissemination: Drafted a peer-review paper, delivered internal seminars, and up-skilled staff in thermochemical conversion and sustainable pavement technologies.
Collectively, these outcomes confirm microalgae derivatives as technically viable, low-carbon alternatives to petroleum-based asphalt constituents.
Conclusions
This project demonstrates that microalgae can furnish a dual-purpose bio-oil/biochar system capable of enhancing or substituting conventional asphalt components. Optimised laboratory protocols delivered binders and fillers that match—or surpass—key performance metrics of petroleum bitumen while cutting reliance on finite resources. Having reached TRL 4, the technology now stands ready for scale-up trials: batch-reactor runs, pilot-plant production, and full-scale pavement sections will validate manufacturability, durability, and life-cycle carbon benefits. Success will accelerate adoption of renewable binders, supporting UK net zero infrastructure targets and reducing occupational exposure to petro-derived fumes. Future work will refine bio-oil formulations, broaden feedstock options, and engage industry partners to integrate microalgae asphalt into specifications and procurement frameworks. The pathway is clear: convert laboratory proof into commercial reality, enabling greener, high-performance roads for the next generation.
Next Steps
With proof-of-concept achieved, the next phase focuses on rigorous performance validation and industrial engagement. We will complete mixture-level assessments—rutting, cracking and fatigue—followed by
accelerated loading studies to build a comprehensive dataset for mix-design and life-cycle analysis. In parallel, we are actively looking for commercial partners willing to join the research and help scale pyrolysis from
laboratory grams to pilot-scale tonnes, refining energy use, product yields and QA/QC protocols needed for eventual continuous production. Pending those results, we aim to construct a small experimental road trial
section to evaluate in-service performance of microalgae binders. Site selection and monitoring strategies will be developed once laboratory evidence is in hand and funding secured. Findings will be disseminated
through journal articles, conferences and stakeholder workshops while feeding into a broader net-zero materials proposal to be submitted in 2025.
