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A man who paves India's roads with old plastic (theguardian.com)
138 points by wallflower 5 months ago | hide | past | web | favorite | 46 comments

Lignin from hemp could be a possible bitumen replacement:


Looks like hemp is 5-30% lignin depending on the type, with female hemp having roughly double the lignin content by dry weight:



Also algae oil can be converted to a bitumen-like tar with roughly 55% efficiency, so if we assume the best algae is 50% oil by weight then we end up with about 25% tar by weight (I can't find confirmation of this, so they might mean 55% tar from algae directly):


Perhaps these could be combined with recycled plastic to make an asphalt derived purely from biomass and recycled materials.

The best genetically engineered algae is over 90% oil by weight.

While I applaud the change in perspective into looking at plastic as a resource, not a curse, this article smells of BS:

> He received a patent for the process in 2006. Since then, almost 10,000km of Indian roads have been paved using his technique.

This sounds like random stats thrown around by government officials, particularly because later in the terribly-written article, it mentions:

> Nonetheless, at least 16,000km of road have subsequently been paved in the state of Tamil Nadu. The national government has since approved the idea and sanctioned at least 13,000km across the country to be paved in the material as well. Of this, 8,600km have already been completed, says Dr IK Pateriya of the rural development ministry in Delhi.

The numbers simply don't add up.

> Shredded plastic below 70 microns (including the multi-layer plastic shreds) is then sprinkled over it.

A shredder capable to shredding materials down to 70 microns is absurdly impressive, and would likely cost hundreds of thousands of dollars. Unless the article means that some of the plastic films being used have a thickness of 70 microns. Honestly, it just looks like the author read 70 microns in the source material and threw it in to impress without knowing what it means.

> A stone tile measuring one square metre has a manufacturing cost of Rs 100, approximately £1.. 60 plates would be sufficient to construct an eco-friendly bathroom, says Dr Vasudevan.

£60 to build a toilet in India, plus labor, construction, etc? This is a very bad idea. The median household income per capita in the poorest states in India is under $1000/year. Just the cost of the toilet is much higher than the median monthly household income of one person.

That's before we get into the issue of using cement and concrete in the "plastone", which are very carbon-intensive (concrete generates about 400kg of CO2 per cubic meter). It would be much cheaper, simpler and greener to use wood to build it, which can be carbon net-negative.

You might be surprised to know that the govt. spends around 220$ to build a single toilet in small towns / villages in India under the Swachh Bharat's sanitary division.

I even have a friend who found it super lucrative to build toilets around his factory for the govt. and hence took it up to build a few toilets every day to add a stable revenue source.

This may not add up given the per capita, but that's how it is, welcome to India.

Rural toiled fund allocation raised to Rs. 15000 per toilet:- https://www.thehindubusinessline.com/economy/policy/rural-to...

"The problem [in India] isn't just a lack of toilets -- it's a lack of toilets that people want to use."

National Geographic's deep-dive on the issue: https://www.nationalgeographic.com/magazine/2017/08/toilet-d...

Yeah, I'm quite aware of that being an Indian and living here all my life.

Bill gates has written about this problem as well. Heck we've even got comedy movies surrounding this issue.

However, the toilet building programs are isolated from these facts, they don't even have proper maintenance programs in place to make sure their usable. Every infrastructural spend in India has leakage of money towards those who have power.

Its mostly true. Here is the patent received in 2006 http://www.allindianpatents.com/patents/198254-a-new-mix-pro...

Lots of roads in many countries have been paved using this technique however the exact numbers are tough to calculate.

The 70 micron number is sort of wrong. The films used must be less than 70 microns in thickness (relatively thick plastic bag such that they can easily shred) but they are only shredded to between 2mm and 6mm in length/width.

Oh, I'm not doubting that the method exists. I'm doubting that it is as efficient as portrayed in the article, a good solution for using plastic, and as widely used.

Plastic litter is everywhere in India due to lack of litter management.

In that reality, regardless of the efficiency, solutions like this that target the symptom rather than the root problem get attention.

> Plastic litter is everywhere in India due to lack of litter management.

Certainly this is true. But assume that litter management improved in India: they would still have to dispose of the plastic litter.

Isn't the point that it can be disposed of by paving roads?

The problem is scale. Indians use 10kg of plastic per person per year, so 13M tons per year. If India were to pave 10 thousand km of roads per year with this tar/plastic combinations (completely unrealistic), it would use up only 10 thousand tons of plastic, or a meager 0.8% of all plastic consumed in India.

Only commenting on India's plastic consumption [1]:

India which, despite its 1.3bn people, falls outside the top ten of the plastic polluters (8 of them are in Asia) thanks to armies of ragpickers.

A related useful read on the relatively less harm caused by Plastic compared to other pollutants[2].

[1] https://www.economist.com/leaders/2018/03/01/dont-bin-plasti...

[2] https://www.economist.com/international/2018/03/03/the-known...

Perhaps after some years, that percentage will increase to "life changing" level. It all boils down to the motivation of the folks who has the means to make the change.

10,000km of new paved roads per year? At an Indian scale, that seems pretty minuscule.

I found an interesting article that breaks down some of the potential problems with this process and the risks involved with heating plastics and trying to differentiate between plastic and PVC (they release different compounds when heated, both potentially problematic). https://www.thenewsminute.com/article/heard-about-miracle-pl...

> the risks involved with heating plastics ... (they release different compounds when heated, both potentially problematic)

The article makes this claim:

> Studies reveal that even heating plastics such as PP, PE and PS releases moderate to highly toxic emissions – carbon monoxide, acrolein, formic acid, acetone, formaldehyde, acetaldehyde, toluene and ethylbenzene.

Citing this[1] paper. But the paper only shows toxic emissions from recycling plants operating at 200-300 degrees Celsius, not at 165 degrees Celsius (ie the peak temperature of asphalt).

[1] http://www.sciencedirect.com/science/article/pii/S0045653508...

edit: btw the article's broken vimeo link was the trailer to Chris Jordan's incredibly powerful film Albatross (then titled Midway): https://www.albatrossthefilm.com/, https://www.youtube.com/watch?v=PLkTTJW4xZs

From the OP's article:

> Asphalt is heated to a temperature of 170C (338F). Shredded plastic below 70 microns (including the multi-layer plastic shreds) is then sprinkled over it. The bits of plastic seemingly disappear, melting into the red heat.

"seemingly" disappear. How is this any different than, say, the banned "microbeads"? This just puts tiny fragments of plastic into the environment, which is even more difficult to collect/recycle/sequester than plastic bags and bottles. I think this is a well-intentioned, but overall terrible idea and I hope they are forced to find a better solution.

I may not be fully understanding this, but isn't this process just going to make the Ocean plastic pollution a lot worse?


Indian Monsoon Rains wear away the plastic from the road over few months, years....

The plastic particles drain and make it to the rivers.... eventually to the indian ocean...

... few years later, we now have large scale plastic particle pollution in the indian ocean thanks to this ingenious technique of mixing plastic with bitumen.

I doubt it.

Unless the paved roads are physically close to the Ocean it's unlikely the plastic will be washed away to ocean water. (BTW: Plastic decomposes much faster in sea water than on land - again that doesn't make it ok to dump it in sea water though )

Furthermore the plastic is "heat treated" and then mixed/layered with Bitumen. While the chemical reactions have not been explained it's likely that some form of chemical binding is happening at those temperatures i.e. Plastic is undergoing chemical conversion - at least at amalgam level.

It doesn't have to drain to the ocean, just to the nearest body of water, which will take care of the rest of the journey, no?

Little bit disappointing. Instead of 10 parts of bitumen, it requires use 9 parts of bitumen and 1 part of plastic. Add to that the heating of plastic to a tight upper bound lest it releases toxic fumes.

> Add to that the heating of plastic to a tight upper bound lest it releases toxic fumes.

165 degrees Celsius is the maximum temperature for asphalt itself[1][2], so conventional spreading equipment is designed not to exceed that. The plastic is melted by the hot asphalt, not separately.

[1] https://www.fhwa.dot.gov/construction/reviews/revhma01.pdf

[2] "Hot mixed asphalt is manufactured at temperatures between 270°F and 325°F." (that's 132-163 degrees Celsius) https://www.forconstructionpros.com/asphalt/article/10297263...

>> Plastic wouldn’t clog our oceans or our landfills if we didn’t throw it there in the first place.

The big worry isn't so much the oceans being "clogged." It's the microplastics. It's the tiny bits of plastic that bio-accumulate. The turtle choking on a plastic bag is one problem, the repercussions of plankton absorbing tiny beads of plastic into their cells another. Making roads out of bulk plastic doesn't help the microplastics issue. Spreading it out over thousands of miles of road may actually be worse than landfill it in a single place.

I seem to recall that asphalt may be ripped up and recycled -- I wonder if this stuff can be recycled the same way.

If anyone could help, I'm working with a company led by a young woman in Kenya who is actively creating paving bricks out of used plastic bottles. They need about $25k-$50k for machinery to help scale out the operation, and we're trying to find some people who can help secure this funding. Contact me if you'd like to help with doing something good with them.

Her company website: https://gjengemakers.wixsite.com/mysite

Looks scammish

I suppose that is probably true that a lot of very early stage startups may appear that way. That said, I've worked directly with them in Kenya and can attest to the fact that it's not and they are doing good work pushing this concept forward. If you have suggestions for other things that would help establish the veracity of things, do let me know.

While I can't say anything about GP's post, the Gjenge organization doesn't seem to be scammy per se. It pretty interesting to scroll a bit through their Facebook timeline and see another world [1].

One which seems to be heavily influenced by a European and Canadian conference / competition for African entrepreneurs. While there are some photos of 'plastic bricks', the products predominantly seem to be conference demos, especially the mobile app [2].

[1] https://www.facebook.com/gjengemakersltd/

[2] https://play.google.com/store/apps/details?id=com.noriega.g_...

what machinery is needed?

They need 3 machines specifically, one is for heating the material, one for pressing it, and one for forming it. I'll see if I can get the listing of the machines as she has already found the ones available for purchase locally.


You should have her contact him. He has done some work involving pressed bricks with post-consumer waste, and in fact has taught a class at MIT where part of the coursework includes making bricks using recycled materials mixed with earth and cement.

For this to work, the roads need to be better or same quality, and the usage of plastic needs to be more economically efficient.

Road quality being the same, the addition of plastic, including the labor, additional equipment costs of spreading it, storing it, producing it, must be cheaper than the cost of using just the bitumen.

Additionally, processing the recycled plastic has to be cheaper than just making new plastic for this process in the first place.

If this works out, it would be a good use of some waste materials.

> 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.

This is a tall claim that needs substantiation. I'm no chemist, but I think most organic compounds, plastics included, break down with heat and light exposure.

Perhaps he thinks his process makes the plastic break down more slowly, but again, evidence needed.

I read recently about children getting cancer from sports fields made from recycled car tyres.


References abound but here’s the top one https://www.google.com.au/amp/s/amp.cnn.com/cnn/2017/01/27/h...

I’d think twice before making roads from (even more) toxic chemicals.

Do we not get to see a picture of such a road, or am I missing it?

snambi 5 months ago [flagged]

plastic is disgusting. no matter however we disguise it.

Maybe so, but please don't post unsubstantive comments to Hacker News.

Literally half of your posts are unsubstantive and tell other people what to do, like a control freak. Hypocrisy, thy name is dang.

That's true of course, except that it's my job and, alas, the community doesn't solve this problem without effort. Some medicines are toxic but one uses them when the alternative is worse. I wish we knew a better way.

In case it helps, these comments are even more tedious to write than they are to read.

How about simply allowing conversation to just happen? Would you like it if I told you how you were to speak out in public?

It's the GOLDEN RULE. Something you seem to have forgotten in its entirety. You're literally trying to treat someone as if you were their parent. You shouldn't be surprised to find people like me stepping up since you've already coerced people into cowering down.

Unfortunately all our experience with internet forums is that "allowing conversation to just happen" leads to the death of the forum. At least once the forum gets beyond a certain size.

dang is the site admin.

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