The USA used to export much of its waste and garbage to China, but that country cracked down on the trade a couple of years ago. A lot has been dumped in Third World countries, where corrupt authorities could be bribed to accept it and nobody cared about the damage to communities and individuals. However, there’s simply too much of it to be absorbed in that manner – so what do we do with it now? Traditional recycling can’t absorb that much waste, even if consumers could be persuaded to segregate their garbage into categories for the purpose – much less keep it clean, so it can be reprocessed easily.
The BBC reports on one potential solution, particularly given our need to rebuild much of our transport infrastructure.
On a road into New Delhi, countless cars a day speed over tonnes of plastic bags, bottle tops and discarded polystyrene cups. In a single kilometre, a driver covers one tonne of plastic waste. But far from being an unpleasant journey through a sea of litter, this road is smooth and well-maintained – in fact the plastic that each driver passes over isn’t visible to the naked eye. It is simply a part of the road.
This road, stretching from New Delhi to nearby Meerut, was laid using a system developed by Rajagopalan Vasudevan, a professor of chemistry at the Thiagarajar College of Engineering in India, which replaces 10% of a road’s bitumen with repurposed plastic waste.
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It has the benefit of being a very simple process, requiring little high-tech machinery. First, the shredded plastic waste is scattered onto an aggregate of crushed stones and sand before being heated to about 170° Celsius [338° Fahrenheit] – hot enough to melt the waste. The melted plastics then coat the aggregate in a thin layer. Then heated bitumen is added on top, which helps to solidify the aggregate, and the mixture is complete.
Many different types of plastics can be added to the mix: carrier bags, disposable cups, hard-to-recycle multi-layer films and polyethylene and polypropylene foams have all found their way into India’s roads, and they don’t have to be sorted or cleaned before shredding.
As well as ensuring these plastics don’t go to landfill, incinerator or the ocean, there is some evidence that the plastic also helps the road function better. Adding plastic to roads appears to slow their deterioration and minimise potholes. The plastic content improves the surface’s flexibility, and after 10 years Vasudevan’s earliest plastic roads showed no signs of potholes. Though as many of these roads are still relatively young, their long-term durability remains to be tested.
By Vasudevan’s calculations, incorporating the waste plastic instead of incinerating it also saves three tonnes of carbon dioxide for every kilometre of road. And there are economic benefits too, with the incorporation of plastic resulting in savings of roughly $670 (£480) per kilometre of road.
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Similar projects have emerged around the world. The chemicals firm Dow has been implementing projects using polyethylene-rich recycled plastics in the US and Asia Pacific. The first in the UK was built in Scotland in 2019 by the plastic road builder MacRebur, which has laid plastic roads from Slovakia to South Africa.
MacRebur has also found that incorporating plastic improves roads’ flexibility, helping them cope better with expansion and contraction due to temperature changes, leading to fewer potholes – and where potholes do happen, filling them in with waste plastic otherwise destined for landfill is a quick fix.
There’s more at the link.
Many of our larger cities are already choking many smaller communities by “exporting” their garbage and waste products to landfills far from their own populations. That’s happening on the outskirts of the small town where I live, too. If something like this could reduce the flow (and the resulting contamination of the environment) we’d all benefit – but the problem will be to get it started, when many of the existing powers that be are making good money out of the present mess, and have little financial incentive to change. It’ll take some doing.