Tech & Sci
2021.11.27 01:26 GMT+8

The plastic roads built using a million unwanted plastic bags per mile

Updated 2021.11.27 01:26 GMT+8
CGTN

 

We all know there is a global plastic pollution problem. Five trillion single-use plastic bags are used every year. One million plastic drinking bottles are purchased every minute. 

But what if we could use the plastic that would normally end up in landfill or incinerators for something else? That's exactly what Toby McCartney is trying to do with his company MacRebur. 

RAZOR's Frankie McCamley went for a drive on one in Lockerbie, Scotland.

"This is the first plastic road to go down anywhere in the world... You'll notice there are no potholes in it," says McCartney.

That's true. It also looks just like any other road – it's not bouncy, even though there is plastic in the mix of asphalt that's produced to form the road. 

The idea was sparked by a trip to India.

"I remembered something that I'd seen in India where they were employing people as pickers and they would go and pick out various items of plastic litter. They would stick it into potholes, pour diesel all over it, set it alight, all the stuff would melt down and form a seal in the hole," recalls McCartney.

 

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"I knew, with limited chemistry background, that there must be some genetic code between the plastic, which comes from an oil-based compound that's fracked from the ground, as well as bitumen, that could get one back to the other. And so that's what I started to do," he adds.

The initial test was on his driveway six years ago. It proved successful and the company was formed to commercialize the idea and after a lot of testing and trialing they think they have found the perfect recipe.

But to begin the process of building plastic roads, you need a lot of waste plastic. Luckily, there's no shortage of that.

And they use plastics that can't be recycled and would be destined for landfill, incineration or ending up in the oceans.

"So, for every one mile of road that we put down with our plastics, we're using over 1 million single-use plastic bags in that mix. Colossal amounts of waste plastics that we can use up in the roads," he adds.

 

How do you get this plastic into roads? 

"A road is basically essentially made up of two different things. So you've got your aggregates or your stone, as most people would call it, and that is stuck together to make a road with what we call bitumen, that's the black oil. So our plastics are used to replace part of that bitumen that goes into that mix."

Plastic and bitumen both originate from crude oil, which is formed of long chain hydrocarbon molecules. When distilled in a refinery, the oil is separated into fractions, which are a mix of hydrocarbon chains. One of these fractions, naphtha, is the crucial compound used in plastics. After removing the lighter fractions, the heavier components, including bitumen, fall to the bottom.

"Although we call it a plastic road. There's no actual plastic in it. The plastic is homogenized to form a homogenous mix with the bitumen that sticks stones together. And what plastics can do, as an example, is we can make that bitumen more stretchy or we can make it not melt at quite the temperatures that a standard bitumen might melt at," he says.

 

What happens if it rains? Are microplastics running off into our drainage?

"It's a really good question, but the answer is absolutely not. There are no microplastics as you look at this piece of road. You can see that there are aggregates, you can see that there's bitumen, but that bitumen has formed a homogenous mix with the plastics that have gone into it. So there are no microplastics present to leech off," McCartney says.

 

What about the future?

"We also produce machinery here so that people can use local waste plastics in local roads, and that's really where it's at for us," says McCartney.

The company sees itself as part of the circular economy.

"We're taking the stuff that cannot be recycled currently, forming a new style, a new form of recycling, and then at the end of the lifetime of that road, it can be planed back up, reheated, more waste plastics added to it, and that road goes straight back down as a brand new road that forms the sort of the bigger circle of the circular economy with regards to asphalt. 

"So we're just a small part of ending the plastic epidemic, but it's nice to be part of that rather than causing the problems that we see around the world today with plastics in our environment and everywhere. So I just don't want my daughters to live in a world where there are more plastics in our oceans than fish ... it just shouldn't be that way."

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