India’s Plastic Roads – WTF fun fact
‘we are dumping all this waste that will not biodegrade and will still be present intact in hundreds of years’
‘we also have these roads that degrade in less then twenty years and need frequent costly repairs’
‘guess these two completely unrelated problems will never be solved’
WHAT ARE WE WAITING FOR
Alright, I’ve done a bit of digging and I’d like to add some things.
1. These are plastic composite roads- not pure plastic. It seems like what they do is shred the plastic, melt it down, and mix it with bitumen. There seems like there’s also one project that uses plastic(specifically LDPE, or shopping bag plastic) as an additive(unclear whether the plastic is acting like a binder), and it’s generally unclear how much plastic and how much asphalt is happening, which probably means everyone’s just doing their own thing, as is frequently the case in super-new stuff.
The exciting part of this is having a way of getting rid of all the consumer waste that’s being produced and the savings on bitumen- you can replace up to 10% of the bitumen with plastic and it’ll still work fine. I believe that this might end up in a similar niche as pozzolans(fly ash, slag, etc) in concrete– using something that’s typically a waste to decrease how much of the other stuff you need and having your cost and carbon savings happen that way, while also somehow ending up with a better product.
2. “No potholes have developed”- I’m skeptical of this claim, so I dug deeper into it. The guy who developed it, and the project which i believe is being specifically mentioned here, reports that the tensile strength and flow characteristics of the plastic-bitumen composite is better, and has a bunch of photos showing the conditions of the roads some years after laying.
I’m not fan of this sort of sampling, because it seems kind of cherry-picked. I’m particularly skeptical of the claim that the roads resist UV because the #1 thing you learn in polymers is that combining UV and heat is the single best way to degrade a polymer. So, we’ll see.
That being said there also seems to be some synergistic effects between the bitumen and polymer, and it’s probably better than just bitumen, since the plastic will encase it and make the bitumen last a little longer. I’m wondering what happens when the plastic degrades, and how the plastic will degrade.
My brief foray into the published scientific literature[modification with a bunch of other stuff including old tires, ageing characteristic, a study on freeze-thaw resistance] seems to suggest that UV degradation may be a problem, as do drastic temperature changes. I’m going to have to do more research on this, but I do think that “not a single problem after four years” is a suspicious, at best, claim to make, and to imply that there are no problems after fourteen years as the screencap states is ridiculous- no one ever claimed that, not even the author!
tl;dr: yes, it’s a fantastic, and very exciting, and I do mean ingenious way of getting rid of plastic trash. It will probably beat raw bitumen in performance and durability. It will definitely be cheaper, especially if you have some process to sort the plastic in place, because quite a few places will pay you to get rid of it.
However- the durability(and safety- does traffic generate clouds of microplastic through friction?) is a bit more up in the air. There’s surprisingly little written about this, considering how novel the idea is and how long it’s been(Dr. Vasudevan got the patent in 2002, so what’s happening?).
I wonder if it might be more useful for the underlayers, away from the UV bombardment.
In any case, it’s still a place to put plastic waste that isn’t a landfill, so.
Nava 