Self-healing asphalt could solve UK pothole challenge

Scientists from King’s College London and Swansea University, in collaboration with scientists in Chile, designed the self-healing asphalt, which does not require any maintenance or human intervention.

“These advanced solutions aim to prevent the early-stage cracking of roads autonomously, thereby reducing their progression into future potholes,” said Dr Jose Norambuena-Contreras, a senior lecturer in the Department of Civil Engineering at Swansea University.

Cracks occur when bitumen hardens through oxidisation, but the exact processes behind this are unknown. The team found a way to reverse the cracking and develop methods to ‘stitch’ asphalt back together.

During the research, machine learning was used to study organic molecules in complex fluids like bitumen. The team developed a new data-driven model to accelerate atomistic simulations, advancing research into bitumen oxidation and crack formation. The team is also collaborating with Google Cloud to simulate the behaviour of the bitumen on a computer.

To make the asphalt ‘self-healing’, the team incorporated ‘spores’, which are tiny porous materials made from plants. The spores are filled with recycled oils, which are released when the asphalt begins to fracture. This reverses the cracking process.

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“The capsules are embedded within the asphalt mixture of the pavement,” said Dr Norambuena-Contreras.” This means they modify the bitumen and integrate into the material, though they are not directly exposed to the environment, as they remain inside the asphalt. In this sense, the spore acts as an additive that enhances the asphalt self-healing without being directly exposed to water.”

Scientists are increasingly using recycled materials in asphalt to reduce the use of fossil fuels and make roads more sustainable.

In laboratory experiments, this advanced asphalt material was shown to completely heal a “microcrack” on its surface in less than an hour.

Potholes are a substantial issue in England and Wales, where £143.5m is spent annually to fill them in, with an estimated £16.3bn needed to bring roads up to satisfactory standard.  

Dr Francisco Martin-Martinez, an expert in computational chemistry at King’s College London, said: “Creating asphalt that can heal itself will increase the durability of roads and reduce the need for people to fill in potholes.

“We are also using sustainable materials in our new asphalt, including biomass waste. This will reduce our dependence on petroleum and natural resources. Biomass waste is available locally and everywhere, and it is cheap. Producing infrastructure materials from local resources like waste reduces the dependence on petroleum availability, which helps those areas of the world that have limited access to petroleum-based asphalt.”