Researcher at Swansea University says tiny plant spores mixed into bitumen can extend surface lifespan by 30%
For all motorists, but perhaps the Ferrari-collecting rocker Rod Stewart in particular, it will be music to the ears: researchers have developed a road surface that heals when it cracks, preventing potholes without a need for human intervention.
The international team devised a self-healing bitumen that mends cracks as they form by fusing the asphalt back together. In laboratory tests, pieces of the material repaired small fractures within an hour of them first appearing.
“When you close the cracks you prevent potholes forming in the future and extend the lifespan of the road,” said Dr Jose Norambuena-Contreras, a researcher on the project at Swansea University. “We can extend the surface lifespan by 30%.”
According to the AA, a record £579m was spent in the UK last year repairing vehicles damaged by potholes, up from £474m in 2023. After pledging £1.6bn to repair roads and fix more than 7m potholes in England this year, the transport secretary, Heidi Alexander, said the hazards had “plagued motorists for far too long”.
Potholes typically start from small surface cracks that form under the weight of traffic. These allow water to seep into the road surface, where it causes more damage through cycles of freezing and thawing. Bitumen, the sticky black substance used in asphalt, becomes susceptible to cracking when it hardens through oxidation.
To make the self-healing bitumen, the researchers mixed in tiny porous plant spores soaked in recycled oils. When the road surface is compressed by passing traffic, it squeezes the spores, which release their oil into any nearby cracks. The oils soften the bitumen enough for it to flow and seal the cracks.
Working with researchers at King’s College London and Google Cloud, the scientists used machine learning, a form of artificial intelligence, to model the movement of organic molecules in bitumen and simulate the behaviour of the self-healing material to see how it responded to newly formed cracks. The material could be scaled up for use on British roads in a couple of years, the researchers believe.
The RAC estimates that, on average, drivers encounter about six potholes per mile on council-controlled roads in England and Wales. The holes can put lives at risk and leave motorists with bills for repairs of hundreds to thousands of pounds.
In 2022, Rod Stewart shared a video of himself filling in potholes on a local road after an ambulance’s tyre burst. “My Ferrari can’t go through here at all,” he complained.
The singer, who wants a hard road to travel, said he was considering selling his collection of sports cars because the roads around his home in Essex were so riddled with the pits. “Unfortunately, because of the potholes on our roads, I may have to find new owners for them,” Stewart wrote on Instagram at the time.
National Highways, the government agency charged with operating, maintaining and improving England’s motorways and major roads, said smart road materials that repair themselves were among the technologies it was investing in.
“From predicting where maintenance is needed on the real-life road network to self-repairing road surfaces, National Highways is committed to using technology to make our motorways and major-A roads safer and greener for the future,” a spokesperson said.
“This research will mean improvements and maintenance will be delivered more quickly with less disruption and road users will have a far better end-to-end journey experience, with savings on time and the cost of travel.”
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