Slashdot Mirror
Plastic Roads Sound Like a Crazy Idea, Maybe Aren't
schwit1 writes with news that the Dutch city of Rotterdam is looking at partnering with a company called VolkerWessels to test a prototype plastic road for safety and durability. "They envision pulling waste plastic out of the oceans, and then processing it into prefabricated sections of road with integrated utility channels and drainage. The composition and structure of the plastic makes it more durable than traditional asphalt, and VolkerWessels estimates that their plastic roads should last about three times as long as traditional roads." The roads are manufactured at a factory, and then hauled in a mostly finished state to where they'll end up. This could dramatically reduce the time during which drivers are inconvenienced by road construction efforts.
Pothole in plastic? Pour molten plastic in? Buy a new section of road?
Potholes form in asphalt when water settles into slight depressions. The water softens the asphalt, and then traffic deepens the depression, allowing more water to settle. Freezing and thawing makes it even worse. The plastic road in TFA is perforated, so water drains into a series of tubes. So potholes should not form in the first place. Even with asphalt, potholes can be greatly reduced with proper grading, and by adding fiber.
But I don't think this plastic road is a serious proposal. They may build a few hundred meters as a PR stunt. You cannot collect plastic from the sea cost effectively, and you aren't going to make a good road surface out of random trash.
Normally...
Plastic is slippery when wet
Plastic is brittle when cold
Plastic melts in heat
Plastic is flammable
Plastic is a more uniformed structure while asphalt is more jumbled. This jumbled makes it more complex and backups its own downsides.
If something is so important that you feel the need to post it on the internet... It probably isn't that important.
Another point - plastic degrades with UV exposure. It becomes hard and brittle.
Even if we assume that they have magically found a way to get and recycle the plastic garbage in a few bazillion cubic meters of ocean, they'll still have to do better with the end result than experiments so far. The Morrison Bridge in Portland OR has a skid resistant polymer deck that is already coming apart after just a couple years. I wouldn't write this idea off a priori but there major problems to overcome.
http://www.theoceancleanup.com... is the curent page for the project Boyan Slat started that got some coverage back arround 2013 http://www.dailymail.co.uk/sci...
They are also a little more dangerous for heavy trucks. A friend drives a 16-wheel dump truck with pushers and a strongarm, and apparently if he has to panic-stop the rubberized-asphalt roads are more prone to surface melting and turning to liquid under the tires, effectively making the truck hydroplane in otherwise dry conditions. Nothing like fifteen tons of uncontrollable truck sliding at freeway speeds toward a stupid motorist that cut-off the truck...
I've also noticed they're not nearly as durable as the hard concrete surfaces they replace. There are stretches on most of the oldest coated roads like the I-17 around the Durango Curve and on the US-60 where it diverges Eastbound from the I-10 where the coating has been scraped off in patches, and there are other sections where the coating has split above the control joints in the underlying concrete, making the road noisy again.
I won't deny they're beautifully quiet when new, but they just don't age very well.
Do not look into laser with remaining eye.
As this is an article about Dutch roads. Most highways here have a top layer of asphalt; this is a mix of materials which include: rubber, plastics, stone, zand, and a tar like binding agent called bitumen.
It is designed to make highways be able to drain water, have a rough structure for grip on tires and to reduce noise pollution, and handle the temperature and humidity changes of the Dutch climate.
https://nl.wikipedia.org/wiki/Zeer_Open_Asfalt
There are some pictures of the top layers of a Dutch highway. And lots of text in Dutch, but no link to an english page.
As I mention that asphalt layer is only the top 7 cm of a highway, below it are:
- 3 layers of 6 cm each of asphalt/concrete slabs
- 30 cm of unbounded foundation
- 70 cm of sand
Below this a foundation of Styrofoam blocks may be used on very soft ground to reduce sagging.