Willmott Dixon has addressed CM readers’ questions about its use of an innovative method to replace carbon-intensive bitumen with non-recyclable plastic on roads at a Bristol housing development.
The contractor claimed that the new method would save the equivalent of 150,000 single-use plastic bags that would otherwise have gone to incineration or landfill, while the asphalt would also be more flexible thanks to the plastic, reducing the risk of cracking and potholes.
Reader Jonathan Baldwin questioned what would stop micro-plastics being washed into watercourses as the road abraded with use, while “Nic” asked if the method could be applied to A-roads, motorways, runways or taxiways.
Answering Jonathan Baldwin, a spokesman for Willmott Dixon said: “This is a brilliant question Jonathan and it deserves a good answer. Plastic has been used in road construction since the ‘60s. These plastics are added into asphalt to create what is known as PMB (Polymer Modified Bitumen) and we are doing exactly the same thing.
“We take plastic waste, out of green bins (less than 30% of UK plastic waste is recycled) and instead of burning or burying this valuable material, we mix it with our activator. This activator bonds at one end with plastic and the other with bitumen, this creates a WPMB (Waste Polymer Modified Bitumen).
“So in one move we reduce the amount of oil-derived bitumen being used, we reduce the amount of CO2 being released and we give value to plastic waste. Asphalt roads can continuously be recycled, meaning we have created a closed loop whereby this material is locked in our roads indefinitely. We have had to make sure that this assumption rings true and have had to do a lot of testing in the background, with universities to make sure that as cars, buses and HGVs roll over the surface we have not got plastic leeching out into the soil and watercourses, we have categorical evidence that this is not the case.
“Far worse to have these plastic burned into the atmosphere, or dumped indefinitely underground where they leech out into the soil and water courses, or even worse than those two options, plastic waste being dumped directly into rivers and seas.”
Answering Nic, the spokesman said: “This waste plastic material has been used on 800+ roads in the UK mainly in the north east of England. Starting in 2016 in Cumbria on small schemes, repairing damage of storm Desmond, and now in 2019 on the A689 dual carriageway.
“This will be rolled out as we gain more credibility and have our materials used on Highways England Strategic Road scheme. In 2017 Carlisle airport had their taxiway and runway paved with this material. We are a long way off being used on Heathrow’s 3rd runway however, we are trying.”