ZAP
Microscopic algae oil creates asphalt that is more resistant to moisture, increases flexibility and reinforces the asphalt’s “self-healing” behavior. It also promises to abandon carbon.
The asphalt that covers roads, streets, airport runways, bike paths and even roofs has a common denominator: it is born from . Although it is a relatively cheap, flexible and recyclable material, it is also vulnerable to extremes in temperature and humidity, which accelerates degradation and requires frequent repairs.
It is in this context that an unexpected proposal arises: replacing part of the traditional binder with microscopic algae oilwhich creates potentially more resistant and more sustainable asphalt, advances .
Conventional asphalt is composed, on average, of 5% to 10% bitumen and 90% to 95% of aggregates, such as gravel, sand, crushed stone or mineral powder. To improve performance, modifiers can be added, such as recycled rubber, antioxidants or fibers. But even then there are limitations: heat and cold affect its elasticity and water favors cracks and holes.
A team of researchers led by Elhan Fini recently developed an elastic and sustainable binder made from algae oil, presented as a partial alternative to the petroleum-derived binder. According to the researcher, compounds of algal origin can improve moisture resistance, increase flexibility and reinforce the “self-healing” behavior of asphalt.
According to the study in November in ACS Sustainable Chemistry & Engineering, scientists used computer models and analyzed oils from four species of algae, looking for options compatible with the solid components of asphalt and capable of maintaining performance in freezing conditions.
One microalgae stood out: Haematococcus pluvialisa green freshwater species. Its oil showed greater resistance to permanent deformation in traffic simulations and better protection against damage associated with humidity, the main culprit behind the formation of potholes on roads.
In tests with repeated loads and freeze-thaw cycles, asphalt enriched with algae showed improvements up to 70% in recovering deformation compared to traditional asphalt.
The authors also estimate that replacing just 1% of the fossil binder with algae-derived material could reduce net carbon emissions from asphalt by 4.5%. With a replacement of around 22%, the pavement could, in theory, become carbon neutral.
The idea is part of a broader ecosystem of alternatives: mixtures with recycled plastics or tire rubber, modular pavements or concrete for heavy traffic, as well as “warm” or “cold” mixtures that consume less energy. But algae-based asphalt, if it confirms technical and economic viability, promises a rare balance between durability, lower maintenance and environmental gains.
