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Strengthening asphalt roads with a unique green ingredient: Algae:
Snow and ice can damage paved surfaces, leading to frost heaves and potholes. These become potential hazards for drivers and pedestrians and are expensive to fix. Now, researchers propose in ACS Sustainable Chemistry & Engineering a figurative and literal green solution to improve the durability of roads and sidewalks: an algae-derived asphalt binder. For temperatures below freezing, results indicated that the algae binder reduced asphalt cracks when compared to a conventional, petroleum-based binder.
"Algae-derived compounds can improve moisture resistance, flexibility and self-healing behavior in asphalt, potentially extending pavement life and reducing maintenance costs," says research team lead Elham Fini. "In the long term, algae asphalt could help create more sustainable, resilient and environmentally responsive roadways."
Currently, asphalt is held together with bitumen: a thick, glue-like substance made from crude oil. Bitumen binds the sand and rocks that make up paved surfaces and allows the asphalt to expand and contract in hot and cold conditions, respectively. However, when the temperature rapidly drops below freezing, the binder becomes brittle and can crack, leading to roadway damage. To improve asphalt's flexibility and durability at subzero temperatures, Fini and colleagues developed a sustainable and rubbery binder from algae oil.
Fini's previous studies showed that oil extracted from algae can make a bitumen-like product that is particularly durable at low temperatures. Continuing this work, Fini and colleagues used computer models to evaluate oils from four algae species for their abilities to produce bitumen-like products that mixed well with asphalt solids and retained functionality in freezing temps. Of the four algal species, oil from the freshwater green microalga Haematococcus pluvialis appeared to impart the most resistance to permanent deformation under simulated traffic-induced stress, as well as enhanced resistance to moisture-induced damage.
In laboratory demonstrations that mimicked road traffic and freezing cycles, H. pluvialis algae-asphalt samples created by the researchers showed up to a 70% improvement in deformation recovery compared to pavement made with a crude oil-based binder. In addition to strengthening roads, the team estimates that substituting 1% of the petroleum-based binder with algae-based binder would cut net carbon emissions from asphalt by 4.5%. At around 22% algae-based binder, asphalt could potentially become carbon neutral. The researchers say this approach paves the way toward high-performance, cost-effective and sustainable pavement infrastructure.
Journal Reference: Mohammadjavad Kazemi, Farideh Pahlavan, Andrew J. Schmidt, et al., ACS Sustainable Chemistry & Engineering 2025 13 (45), 19496-19510 https://doi.org/10.1021/acssuschemeng.5c03860
(Score: 4, Interesting) by VLM on Tuesday January 06, @07:59PM
https://pubs.acs.org/doi/full/10.1021/acs.energyfuels.4c05634 [acs.org]
I keep an eye on oil industry stuff as a hobby and investment. This stuff isn't there yet. Its farmed now to make a natural(ish) red food coloring used to make aquacultured salmon and shrimp meat red (or even redder) and you can turn the waste from making the food coloring, into oil. Much like given an infinite amount of processing, energy, and money, you can turn corn into oil. If seed or veg oils are a good idea at all is a whole nother topic. But yeah you can make oil out of algae waste.
Google thinks the total world production of astaxanthin is like 4000 tons, which is an ungodly shitload of what amounts to red food coloring. I don't know the percentages of waste in the food color process and the percentage of waste that turns into oil, maybe it is beyond the paywall. But if the starting number is small surely the downstream can't be that big.
Sometimes its red sometimes its green. I don't know if the oil is colored (either inherently or via contamination).
Something to consider is even if its ridiculous or unsustainable as full fledged paving, it might be useful for cracks instead of hot tar, or maybe would make an interesting base for paint on roads.
You may get an unintended consequence of "green bio algae oil asphalt" will just result in more asphalt paving. Gotta do "something" with the bitumen and lack of a better idea means it gets turned into asphalt mostly. Well its a hell of a soup of organic chemistry "gloop" so maybe lots more even cheaper means more stuff might get refined out of it.
Another weird unintended consequence is "having" to grow enormous amounts of algae to make oil might make the feedstock for aquaculture even cheaper. So, cheaper farmed fish. OK I guess.