For now, this is a limited advantage in terms of quantities. But given that only 9% of the 350 million tons of plastic produced each year is recycled, advocates of this technology see it as one of the strategies that can help limit damage and facilitate the adoption of fundamental circular economy practices: reduce, reuse, recycle.
Risk of microplastics?
Michael Burrow, a University of Birmingham engineer and author of a global study of this technology, argues that ‘the use of waste plastic in road construction helps substantially improve the stability, strength, durability and other useful properties of bituminous mixtures, leading to better longevity and better pavement performance ».
Many of his colleagues are on the same line. “The beauty of the roads is that there are so many of them,” says Greg White, author of a recent research on the subject from the Department of Road Engineering at the Sunshine Coast University of Australia. So far, four companies have built hundreds of kilometers of plastic-containing roads in Australia.
What is missing, White warns together with his colleagues, is the data of aging and resistance over long periods, because in most countries the technology has been in use for less than ten years.
The general model of the various companies active in the sector is to add waste polymers to bitumen. Asphalt normally consists of 90-95 percent aggregates – gravel, sand or limestone – and 5-10 percent bitumen, a mixture derived from the refining of crude oil that binds the aggregates together. Plastic waste can act as an even stronger binder than bitumen, but it often replaces only 5-10% of bitumen, although some methods use more.