Pregnant with her first child, Raptaki drove into a pothole with such force that it caused her water to break. Mother and child were fine, but the incident was the catalyst in 2017 for the development of Roadworx, a bitumen substitute made from recycled plastics and, latterly, graphene.
According to the Institute of Physics, plastic waste increases the penetration value (a measure of hardness or consistency of bituminous material), softening point and viscosity of bitumen.
“Plastics in roads is not new,” said Raptaki. “What I’m trying to do is to use plastics that are not easily used by another recycling process. If we talk about a circular economy, we need to think wider.”
She continued: “Glass was a very good alternative solution, some years ago, on asphalt; it works perfectly well, it has great results. The reason we don’t use glass…in asphalt is because glass has 100 per cent absorption on the recycling circle.”
In Roadfill’s process, recycled plastic from waste is incorporated into the asphalt mix and used in the road surface layer to create a more durable road whilst retaining sufficient elasticity to reduce the formation of cracks and potholes. The company said it does not work with hot lay asphalt due to its ethical stand on carbon reduction.
The process excludes PVC but does use combinations of waste LDPE (low density polyethylene) and PP (polypropylene) with a melting point of under 150°C.
“If you think of a typical one-kilometre road…we would use an equivalent of two million plastic bags,” said Raptaki. “A real problem with plastics is that for plastic to bio-integrate by itself, we need more than 500 years. If you use that durability to our advantage… we can help the road last longer.”
Roadfill, with offices in England and Scotland, has so far conducted trials north of the border with Tayside Contracts and Bin Group, and in the home counties with Buckinghamshire Council.
Two sections of road on the A40 in Bucks have been laid with Roadworx, namely the busy Oxford Road in Denham and the quieter Orchard Way in Holmer Green.
Waste plastic makes up 0.2 per cent of the material used to resurface the road; on the 280m trial section at Orchard Way the plastic material used is equal to 16,000 recycled 500ml plastic bottles, with approximately 0.5 tonnes less bitumen needed than in traditional asphalt. Work began in November 2022 and the Highways team is monitoring how the material performs alongside more traditional materials.
Roadfill’s ambitions include sourcing waste plastics close to where roadworks and resurfacing take place. The company is also working with Manchester University and Versarian on introducing graphene into their asphalt blends.
In March 2023 Roadfill was named one of the seven winners in the ‘company’ category of #21toWatch, a competition that celebrates smaller innovators across Cambridge and the East of England.
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