Researchers at the University of Nottingham (UoN) in England are developing a technique to make fixing pothole-ridden roads easier, with the help of sunflower oil capsules.

Headed by Alvaro Garcia, lecturer at the faculty of engineering at UoN, the scientists used the spherification technique to create caviar-like sunflower oil capsules that could be placed in the asphalt used to pave roads, the UoN said in a statement on 18 October.

When the road begins to crack, the capsules would break and the released oil soften the asphalt around it, causing it to stick back together and effectively fill any gaps and thus prevent the asphalt from deteriorating further.

Garcia said that he got the idea to develop the capsules after watching an episode of the Spanish version of the Master Chef TV show, where a contestant used a similar method in cooking.

According to Garcia, this new Capheal technology could withstand the mixing and compaction processes in road paving without significantly affecting the asphalt’s properties.

“More importantly, we found that the cracked asphalt samples were restored to their full strength two days after the sunflower oil was released,” Garcia said.

He estimated that the technology could increase a road’s lifespan by at least one-third from 12 to 16 years while costing approximately the same as other common additives used in asphalt paving.

The team was currently examining the structure of the capsules to better understand how they would deteriorate over time, after which they intended to develop capsules of different strengths to find the optimal solution for different asphalt mixes and traffic conditions.

It was also looking at potentially using recycled cooking oil instead of sunflower oil to produce the capsules.

After Garcia’s team finished its tests, the sunflower oil capsules would go for testing with Highways England, the country’s road maintenance authority, which also funded the research project.

“We know road users want good quality road surfaces with fewer potholes and not as many roadworks disrupting their journeys. This self-healing technology could give them that and offer real value for money,” said senior road pavements advisor Robin Griffiths.

“So far, the UoN research is showing real potential in how easy it is to mix and apply, as well as being sustainable and environmentally friendly.”

Highways England was planning to test the product on carefully selected road sections during planned overnight maintenance work and monitor the results over a period of 12 to 24 months.

Despite promising initial results, some experts were sceptical about the further potential of the Capheal technology based on current testing.

N V Ramana, senior professor of civil engineering at Jawaharlal Nehru Technological University in India, said the amount of technical data on the use of sunflower to patch roads was too small to know whether it could work on a larger scale.

“It is necessary for the oil to combine with the bitumen particles and form bonds. This can only be achieved when the correct quantity of oil is used according to the amount of bitumen,” Ramana told the Deccan Chronicle newspaper on 26 October.

He added that filling a pothole with sunflower-enforced asphalt would not solve the problem as the old asphalt around would still crumble like before and would therefore necessitate the complete repaving of the entire road.