
A man who paves India's roads with old plastic - nwrk
https://www.theguardian.com/world/2018/jul/09/the-man-who-paves-indias-roads-with-old-plastic
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thisisit
Wasn't this discussed yesterday?

[https://news.ycombinator.com/item?id=17490990](https://news.ycombinator.com/item?id=17490990)

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tzakrajs
But isn't the problem with plastic in the ground that chemicals would leech
out of it and debris would break off from it and be ingested by animals and
humans? Is a road that much better than dumping it in the ground away from
humans and animals? I worry about physical changes to the road over time. Is
it safe to inhale the dust that is generated from wheels rolling over a sun-
burdened piece of plastic for years?

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ryanx435
from the article:

To environmentalists who believe that the technology could be harmful because
of toxic fumes from plastic residue, Dr Vasudevan points out that the plastic
used is softened at 170C. “Plastic decomposes to release toxic fumes only if
it is heated at temperatures above 270C (518F). So there is no question of
toxic gases being released,” he says. Since plastic coats the stone and
interacts with the hot bitumen, it’s properties change and it doesn’t break
down when exposed to light and heat.

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ryanmercer
You don't need toxic fumes, plastic doesn't go away. It breaks down into
smaller and smaller pieces and contaminates the environment.

See:
[https://en.wikipedia.org/wiki/Microplastics](https://en.wikipedia.org/wiki/Microplastics)

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24gttghh
>The bitumen-modified plastic improved the tensile strength of the road by
making it more durable and flexible. Plastic also prevented pothole formation.
When the layer of molten plastic filled the space between the gravel and
bitumen it thwarted rain water from seeping in and causing structural defects.

Seems like it would break down less than a regular tar-only road and last
longer to boot.

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tzakrajs
It seems like it will help keep the overall rigity of the road but it says
nothing about how the material will break into pieces on the exterior layers.
Plastics are known to cause cancer and other harm to living things when
ingested, and my curiosity is if plastic could be more damaging than the thing
it replaces.

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24gttghh
Myself, I'm not convinced plastic is more harmful to the immediate environment
in this application than the tar/bitumen itself. It does seem the issue of
plastic shedding into the environment has not been investigated enough, but
does tar not leech toxic chemicals as well?

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ryanmercer
This is terrible. Plastic is forever and breaks down into smaller and smaller
pieces entering the environment.

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0xcafecafe
It seems from the article, they have considered that and concluded that since
plastic becomes part of the bitumen, and does not exist as plastic particles.

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ryanmercer
Unless it has chemically changed considerably it's a problem. My impression is
they are saying "don't worry, chunks aren't going to break off because it's
melted into the bitumen" and are wholly ignoring the micro scale.

