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Science Technology

Road Makers Turn To Recycled Plastic For Tougher Surfaces (economist.com) 109

Recycled plastic is already used to make some products, such as guttering and sewage pipes. Now attention is turning to roads. From a report: On September 11th in Zwolle, a town in the Netherlands, a 30-metre bicycle track made from 70% recycled plastic and the rest from polypropylene was opened [Warning: the link may be paywalled; alternative source]. It will be used to test a product called PlasticRoad, which is being developed by two Dutch firms -- KWS, a road builder, and Wavin, a firm that makes plastic piping -- in partnership with Total, a French oil-and-gas firm. PlasticRoad is prefabricated in a factory as modular sections. The sections are then transported to the site and laid end to end on a suitable foundation, such as sand. Because these sections are hollow, internal channels can be incorporated into them for drainage, along with conduits for services such as gas and electricity. For the Zwolle project, sections that were 2.4 metres long and 3 metres wide were used. These were fitted with sensors to measure things such as temperature, flexing and the flow of water through the drainage channels. A second pilot cycleway is being built in the nearby town of Giethoorn.

If all goes well, the inventors hope to develop the idea and make the sections entirely from recycled plastic. Paths, car parks and railway platforms could follow. Eventually, sections for use as actual roads are planned. These could contain sensors for traffic monitoring. In time, the circuits in the plastic roads might extend to assisting autonomous vehicles and recharging electric cars wirelessly. Prefabricated plastic roads should last two-to-three times longer than conventional roads and cost less, the companies claim, mainly because construction times would be reduced by almost two-thirds. Anti-slip surfaces could be incorporated, too, including crushed stones which are traditionally used to dress road surfaces. The sections, when replaced, can also be recycled. But engineers will be watching to see how the track stands up to wear and tear and if the hollow structure causes resonance, which would make such a road unduly noisy.

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Road Makers Turn To Recycled Plastic For Tougher Surfaces

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  • by sinij ( 911942 )
    Where I live they tried adding mulched rubber tires to asphalt, this resulted in road surfaces that are less durable (more potholes) and the practice was abandoned.

    How is this different?
    • by rojash ( 2567409 )
      Jeez, man, this is for bicycling trails, not for regular assfault roads. Big diff.
      • by Anonymous Coward

        "Eventually, sections for use as actual roads are planned."

      • by PPH ( 736903 )

        this is for bicycling trails

        Bicycles wear surfaces just like autos do. Sometimes even more. We had an abandoned Nike missile site near me that was used for decades by four-wheel drivers. No problems. The county closed off motor vehicle access and turned it into a mountain bike trail park. Now the place is seriously rutted and the soil runoff into nearby salmon creeks is significant.

        • by postbigbang ( 761081 ) on Friday September 14, 2018 @04:37PM (#57316364)

          Um, no. Just no.

          You're talking about non-paved surfaces. This is about paved surfaces.

          On paved surfaces, the data says that adding rubber/plastic recycled materials improves durability. Overweight trucks and plenty of them, will still erode them. High traffic volume, wide ambient environment, poor road beds, all will do their share to screw up paved surfaces. Bikes, by their nature, do not present the weight and lateral surface impact that heavy trucks present.

          • by PPH ( 736903 )

            adding rubber/plastic recycled materials improves durability

            OK. But plastic/rubber roads will still wear. And we don't need to change the subject to 'overweight trucks'. Bicycles will wear a road surface, cars will wear a road surface and trucks will wear a road surface. The plastic and rubber might reduce that wear but the resulting debris from all uses will end up floating in the oceans and get into our food supply. No thanks.

            • by postbigbang ( 761081 ) on Friday September 14, 2018 @07:17PM (#57317206)

              Still, no.

              You're concerned over 200lbs distributed over two tires. I'm talking 80,000 pounds distributed over 18 wheels, sometimes more and less.

              I, too, don't want to see plastics in the oceans. Roads aren't paved in the oceans. It's true that particles are leached into aquifers. We don't have good data on how much, what kind, deterioration, and more. If you were looking to stanch plastic pollution, talk to your local grocer, and encourage products made from paper, or better still, re-usable packaging that requires little cleaning before re-use.

              More effective plastic stanching is possible. It's because plastics compressed as described are so strong, that they'll last much longer as paving products, although all the data isn't in yet.

              There are experimental paving stretches across the US. Some involve plastics, tires, stone mill grinds, and many more. Let's see what works best before condemning them. I want to stanch plastics pollution as much as possible. First things first, please.

              • To add to your comment, it's not just 80000 pounds over 18 wheels, it's that wear on a paved surface by a vehicle is a function of the FOURTH POWER of the axle weight.

                So while actual weight presented on each wheel would be 44x that of a bicycle by your example, actual road wear is 62000000x worse for a truck compared to a bike.

          • by sinij ( 911942 )
            Your data is wrong or maybe it is just wrong for climate where I live. Adding recycled rubber notably reduces durability of roads here. They had to redo road near where I live in just 2 years after trying this method.
            • Likely true-- the mix is all important. It's easy to fudge one ingredient for a more expensive one, when no one's looking, or knows hot to evaluate the mix.... just like regular asphalt. Densities are all important.

        • by Anonymous Coward

          Wear on the road is a factor of the vehicles weight. Therefore while a bicycle might wear a road, it is insignificant to the wear caused by a loaded dump truck.

          Here, cause I know your going to start whining:
          https://streets.mn/2016/07/07/chart-of-the-day-vehicle-weight-vs-road-damage-levels/

          • by Ormy ( 1430821 )
            Road wear & tear is proportional to the 4th power of vehicle weight. Anything to the 4th power is slightly unusual in Physics. Buses and trucks cause over 90% of the damage. But that doesn't mean only trucks should pay, there is still a significant cost to build the road in the first place and that should be shared equally.
            • Quite from my intro traffic engineering prof.: âoeOne truck does the same damage as 10,000 passenger carsâ. The ratio is probably similar cars to bikes.
          • by PPH ( 736903 )

            I'm going to pass on a web site that includes "justice" and "empowerment" as factors in road maintenance. I'm also going to ignore anyone who doesn't actually look at tire loading per square inch as a more important factor than big trucks vs little trucks.

            • by rojash ( 2567409 )
              I doubt this 'web site' controls verbiage :) I also doubt anyone cares when someone says they will ignore LOL No offense
        • Damage proportional is to the fourth power of a vehicle's weight, this is one reason why we have weight stations for trucks.

    • How is this different?

      Its probably even worse.

    • if you RTFA there is no asphalt in this material
    • by SpzToid ( 869795 )

      In India, an engineer has been adding plastic to reduce bitumen as an asphalt component; mostly to reduce waste in landfills.

      https://www.theguardian.com/wo... [theguardian.com]

      Which sounded great to me until I read the poster's comment below, with their idea of microplastics in the food chain.

    • That is too bad. Vulcanized rubber tires are expensive to un-vulcanize, in terms of energy. It would be better to have a good use such as roads (and only so many play-grounds).
      Out of curiosity, did they just add it as a topping, or all through it?
  • by Type44Q ( 1233630 ) on Friday September 14, 2018 @03:18PM (#57315910)
    This will DEFINITELY help with the 'mcroplastics in the foodchain' problem.
    • by sremick ( 91371 )

      Seriously. That was my first thought: as these roads get plowed, you're making piles of microplastics that are washing directly into wildlife and the food stream.

      • Where I live, they grind off about an inch of the highway then blacktop it. Which is nothing but an oil product. This is eastern ohio, we constantly get snow. Between the chemicals they use and the plowing. doesn't the same thing happen. All that hazardous waste from the highway gets back into the eco system?
        • by PPH ( 736903 ) on Friday September 14, 2018 @03:50PM (#57316110)

          Which is nothing but an oil product.

          A lot of the volume of blacktop is gravel and sand. Which, when worn down becomes sand. When that gets into water ways, it just settles to the bottom with the other sand. The tar and other heavy petrochemical products do enter the environment, but at a pretty slow rate where they are broken down by biological activity*.

          *We had a city park near me that was found to be an old (WWII era) fuel tank farm. With plumes of fuel soaking into the soil. The solution was to remove the sod, till up the dirt underneath and mix it with some specialized bacteria strains and let it sit for about a year. After that, all the petroleum waste was gone and it's now a park again.

          • Oil and tar [wikipedia.org] are relatively short hydrocarbon chains (less than 10 to a few dozen carbons). There are bacteria which can break them down.

            Plastics are extremely long [wikipedia.org] hydrocarbon chains. Thousands of carbons or longer - if you stretched it out, a single PE molecule can be as long as a fraction of a mm. It's this length which makes them so durable and persistent. Bacteria cannot break them down. They remain stable until ionizing radiation (primarily UV light) breaks them into shorter hydrocarbon chains,
          • A lot of the volume of blacktop is gravel and sand. Which, when worn down becomes sand.

            A lot of the volume is polymers too. Plastic is already mixed in, the difference being is that the quality and grade is tightly controlled as it affects the properties of the road surface.

      • In the Netherlands, plowing is rare enough that it won't be a significant factor. Snow deep enough to need plowing occurs maybe 1-2 times per winter, and many winters we don't have snow at all. Mostly the roads are just salted.

        The biggest source of micro'plastics' from roads is from tire and brake wear. Tarmac roads also produce microscopic particles from road wear.

        Much of this debris collects around the roadside, where the next rainfall will sweep it into the sewer system. The Dutch sewer system is very we

        • by Mashiki ( 184564 )

          In the Netherlands, plowing is rare enough that it won't be a significant factor. Snow deep enough to need plowing occurs maybe 1-2 times per winter, and many winters we don't have snow at all. Mostly the roads are just salted.

          Maybe in the Netherlands, but in most of North America? Not a chance. To make it clear what the OP is saying, I live in Ontario(Canada). Figure there's 400km between the two of us, for him the plowing could be 1-2 times per day. For us, it can be 1-2 times per hour or more. The winters though the US central states, and north eastern states can be severe. ~9 years ago here in Ontario, we had snowfall amounts of 5.7m(19ft) over a 3 day weekend in the southwestern part of the province, that's actually fai

          • Microplastics are not uniquely dangerous. Microscopic anything non-biodegradable can be a problem when it gets into the food chain.

            • by Mashiki ( 184564 )

              Microplastics are not uniquely dangerous. Microscopic anything non-biodegradable can be a problem when it gets into the food chain.

              Yeah, well the world isn't a safe place either. And if you don't want to develop skin cancer, stay indoors and become a vampire to boot.

    • I hope this is a successful endeavor, but I have concerns that the test will hopefully figure out.

      TFS did stateverything that the surface could be dressed in gravel. So hopefully that will take care of traction issues from the plastic itself, but also when the traction layer itself wears smooth. Hopefully this will also minimize plastic wearing off and beingreleased into the environment.

      Repairable is also a concern. It's not like an asphalt road that can be easily patched. Or maybe it can. I didn't RTFA.

      • Yeah, all in all this is a pretty interesting experiment.

        plastic wearing off and beingreleased into the environment.

        There's likely to be some of that. But probably a great deal less than we currently have, with most plastic going unrecycled.

        Repairable is also a concern. It's not like an asphalt road that can be easily patched. Or maybe it can. I didn't RTFA.

        It being plastic, there might be a simple way using heat & resin to patch a bad spot. Or you lift out a section and drop in a new one, I don't know. But I have my doubts about the greatly reduced construction times these guys claim: most of the effort in building new roads seems to go into preparing the right of way, the

    • Why would this help?

      Microplastics come primarily from wear and tear of plastic articles, such as polyester clothing. If we make roads out of plastic, tires will grind off bits of microplastic, which will wash off the road.

      It WILL help with large plastic waste, which can be recycled. But I see this only making the microplastics problem worse.

  • by Anonymous Coward

    This has been done with rubber (not plastic) on our estate in Milton Keynes, UK. When it's done properly it's basically un-noticeable and so far has worn extremely well. I can't imagine doing this with plastic as that's basically a bit stupid given the microplastics 'news' currently in the worlds focus

    However there is food for thought - this stuff basically wears down as dust, and even if it does it slowly there'll be a lot granted, but dust is a lot smaller than your evil microbead problem, so much so t

    • by Anonymous Coward

      Where I am from (nebraska). They tried recycled plastic on several large stretches of road on I80 outside of Omaha. The conclusion was the road wore out about 20%-40% faster than normal. UNL and NDOT did several very good writeups on it. The 'wear' factor was mostly from the crushing amount of 18 wheelers that travel along I-80. It was about half the cost (at the time).

      Now for a bike trail (which is the use case here)? That could work decently. For automobile roads? It is just not as durable than th

    • by Misagon ( 1135 )

      Oh, when the plastic pieces turn smaller than microplastics they become nanoplastics which have a whole lot of other issues for health and the environment. You would not want to inhale it.

      Wear-down of car tyres is known as a significant cause of micro and nano-plastics in the environment. Tyres are usually made of a mix of natural rubber and synthetic rubber - and synthetic rubbers are also plastics, more or less.

      Another significant health issue in colder climates is that studded snow tyres wear down paved

  • by forkfail ( 228161 ) on Friday September 14, 2018 @03:52PM (#57316126)

    For those who can't see past the paywall, there are some pretty good images of the road sections here. [google.com]

  • The things of real consequence here are the cost savings and how well the road can stand up to heavy loads. If it doesn't perform well in those two areas then it will get limited use. It might be exactly what Zwolle wants, Hell it might even be great for all of the Netherlands but for widespread use, one must consider global applications.

  • A 30-metres long bicycle track made in recycled plastic....

    Wait, 30 metres?

    Do you want to have flawed data? Because that's how you get flawed data.

    Make it at least 3 kilometres long, otherwise all your data will be coming from basically the same exact spot.

    • Re:Impressive! (Score:4, Informative)

      by JaredOfEuropa ( 526365 ) on Friday September 14, 2018 @04:49PM (#57316422) Journal
      First they get their data from the exact same spot. If the road stands up to normal use, doesn't wreck bicycle tires, doesn't turn incredibly slippery in rain or snow, isn't riddled with holes after a few frost / thaw cycles, doesn't kill a kitten an hour with microplastics produced by wear and tear... then it's time to build a longer stretch and see if the economics also work out.
  • Wouldn't worn down plastic end up in gutters, and from there into watercourses... and finally the sea?
  • "The Plasticman"

    A lone venturer comes across a crashed plane containing a body wearing the uniform of the USPS (Uniformed Salsa Plastic Service) with a bag full of plastic water bottles.

    He travels down a plastic road, weathered by erosion and sunlight, which chokes him to death before he can reach the town about to be destroyed by plastic beetles. So they die.

    Everyone is happy in their plastic ruins.

    The End

  • They eventually want to make roads out of this product if it proves tough enough. Why not try and get driveways and some parking lots made from this instead? Then it doesn't have to put up with the heavy loads a busy road would put on it but still replace asphalt. Then as the product improves it can begin to replace roads.

  • This is potentially a reasonable application for bikeways and paths, but it's a non-starter for roads. Their claim that adding plastic increases durability is simply nonsense. Road surfaces already contain quite a bit of plastic. Various polymers are mixed into the bitumen in a very controlled way to achieve a wide variety of different grades suitable for different duties, with different road bases, and different environmental conditions.

    On a footpath where this stuff doesn't matter as much you can make the

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