Researchers reveal how algae-derived binders can make asphalt roads more durable and environmentally friendly, especially in cold climates.
Potholes are a persistent nuisance for drivers, especially in colder climates where freeze-thaw cycles wreak havoc on road surfaces. In the United Kingdom, drivers encounter an average of six potholes per mile, despite millions being filled annually. The problem is just as widespread in northern regions of the United States. At the heart of the issue is bitumen, the petroleum-based binder that holds asphalt together. When temperatures drop below freezing, bitumen becomes brittle, leading to cracks and costly repairs. The search for more resilient, sustainable materials is ongoing, and recent research points to an unexpected solution: algae.
Why algae?
Traditional asphalt binders struggle to maintain flexibility in cold conditions, making roads vulnerable to damage. Researchers have turned to hydrothermal liquefaction—a process that converts microalgal biomass into a water-insoluble biobitumen. The ideal binder should remain liquid at high temperatures and viscoelastic in the range of −20 to 60 °C, ensuring it can coat mineral aggregates and withstand mechanical stress.
A team led by Elham Fini, as reported in ACS Sustainable Chemistry & Engineering, explored biobinders made from algae as partial replacements for petroleum-based products. Their study evaluated oils from several algal species, focusing on physicochemical and rheological properties, as well as the potential to reduce carbon emissions. Notably, the freshwater green alga Haematococcus pluvialis produced a biobinder that excelled in resisting permanent deformation under simulated traffic stress and showed enhanced resistance to moisture-induced damage.
Performance and Sustainability
Laboratory tests revealed that asphalt samples containing the H. pluvialis biobinder recovered from deformation up to 70% better than those with conventional binders. Even a modest substitution—just 1% algae-based binder—could cut net carbon emissions by 4.5%. At around 22% algae content, asphalt could potentially become carbon neutral. Algae cultivation for this purpose is practical, as it doesn’t compete for arable land and offers high biomass yields, with the added benefit of recycling wastewater and carbon dioxide.
A novel aspect of the research is the use of polarizability as a molecular-level parameter to assess compatibility between bio-oils and asphalt. Higher polarizability indicates better interaction, leading to improved binder performance.
These findings advance the chemistry-driven design of biobinders and suggest a promising trajectory toward low-carbon, high-performance, and sustainable infrastructure. Algae-derived binders could help extend the lifespan of roads in cold climates and help rejuvenate aging asphalt, restoring its original properties and reducing maintenance costs.
Explore related research in ACS journals:
Bio-Oil Impact on Water Diffusion and Durability of Bitumen: Influence of Aging and Salinity
Albert M. Hung, Mohammadjavad Kazemi, Farideh Pahlavan, Peter J. Valdez, and Elham H. Fini*
DOI: 10.1021/acs.energyfuels.4c05634
Progress and Perspective of Bio-asphalt Preparation, Structural Characterization, and Rheological Properties
Xuejuan Cao*, Yao Quan, Mei Deng, Boming Tang, and Lingyun Kong
DOI: 10.1021/acs.energyfuels.3c04021
Iron-Rich Biochar to Adsorb Volatile Organic Compounds Emitted from Asphalt-Surfaced Areas
Masoumeh Mousavi, Sand Aldagari, Michael S. Crocker, Laura K. G. Ackerman-Biegasiewicz, and Elham H. Fini*
DOI: 10.1021/acssuschemeng.2c06292
Novel Bio-Nanocomposite for Asphalt Pavements: Montmorillonite Intercalated with Castor Oil
Anastasiya Y. Yadykova, Saba Shariati, Elham H. Fini*, and Sergey O. Ilyin*
DOI: 10.1021/acssuschemeng.4c01181
Intermolecular Interactions of Isolated Bio-Oil Compounds and Their Effect on Bitumen Interfaces
Albert M. Hung, Masoumeh Mousavi, Farideh Pahlavan, and Ellie H. Fini*
DOI: 10.1021/acssuschemeng.7b01462
Metal-Loaded Biochar for Low-Emission and Long-Lasting Asphalt
Yi Zhou, Chunhui Shen, Teng Wang, Feng Wang, and Yongjie Xue*
DOI: 10.1021/acssuschemeng.5c04405
Investigation of Balanced Feedstocks of Lipids and Proteins To Synthesize Highly Effective Rejuvenators for Oxidized Asphalt
Farideh Pahlavan, Amirul Rajib, Shuguang Deng, Peter Lammers, and Elham H. Fini*
DOI: 10.1021/acssuschemeng.0c01100
