CoRncrete: A corn starch based building material (2017)

https://research.tudelft.nl/en/publications/corncrete-a-corn-starch-based-building-material

by thunderbong • 2 years ago

152 104 2 years ago

research.tudelft.nl

thevtm• 2 years ago

This has been out for quite a while, there's even a YouTube video from 2015 showing how to make it using a microwave.

https://www.youtube.com/watch?v=b7dYcJaCOMU

acchow• 2 years ago

They mix 225g sand with 50g of corn starch.

It's more "sand based" than "corn based".

aaronblohowiak• 2 years ago

in concrete, cement makes up less than 25% of the mix, and here corn is like 20%, so I think when you're comparing this class of materials (concrete, epoxy granite, concrete), it makes sense to describe in terms of the binder even if it is a smaller % of the complete product.

szvsw8• 2 years ago

All concrete is more aggregate than binder… but it’s the binder that matters from an emissions perspective.

yunohn6• 2 years ago

Well, tbf the paper clearly says it was published in 2017 and the first author is the same person who uploaded the presumably experimental stage video to YouTube in 2015.

orbisvicis• 2 years ago

How does it handle water?

kdtop• 2 years ago

Perhaps they have to seal it so water doesn't get in.

hlieberman• 2 years ago

It's a concrete that: 1) breaks down in water in a day(!), and 2) has a "5 times higher impact on human health and 3 times higher impact on eco-toxicity as compared to concrete.".

Cool research, but I'll pass on using it.

klysm• 2 years ago

Having 'negative' results like this published is so good though because then it's harder to scam people with this idea in the future.

mythas• 2 years ago

Yeah when the CORN-FREAKING-CRETE skyscraper crowd funding video comes out we can all be more skeptical than we were for SOLAR-FREAKING-ROADWAYS.

candiddevmike• 2 years ago

Why do we still use corn based ethanol?

szvsw8• 2 years ago

Alternatively, some other researcher can say “cool, some problems I can try to address with future work!”

Or it can go by the wayside. Both outcomes are fine. But no need to pre-emptively dismiss something that is obviously not being pitched as a production-ready building material…

adrian_b• 2 years ago

There has been another thread on HN, with a research starting from this, which has developed a concrete suitable for use on Moon or on Mars, where there is no danger of it being broken down by water and where its production would be simplified by this choice, because starch must be produced anyway for food, so making concrete does not require additional production facilities.

https://news.ycombinator.com/item?id=41751122

Therefore even research results that do not seem useful in normal conditions may find some circumstances where their use becomes preferable.

szvsw8• 2 years ago

Interesting. The degradation in wet conditions seems like a major challenge to solve.

I initially was skeptical of the utility when I saw the mention of heating requirements, but the temperatures aren’t that extreme, and seem very reasonably achieved with electrified energy sources (which in turn can easily be supplied via renewables).

Being able to produce concrete without the emissions involved with the production of portland cement is a major goal of decarbonizing the building stock, so it’s always good to see new lines of research in this front, even if still in the germinal stages!

ARPA-E Hestia has some cool alternatives (a bit further along in research stages) for those interested:

https://arpa-e.energy.gov/technologies/programs/hestia

danans4• 2 years ago

Being able to produce concrete without the emissions involved with the production of portland cement is a major goal of decarbonizing the building stock

AFAICT, cornstarch has a similar emissions to portland cement:

https://apps.carboncloud.com/climatehub/product-reports/id/7...

szvsw8• 2 years ago

Yep, the authors do a relatively straightforward LCA and estimate essentially equally carbon footprint between concrete and “corncrete.”

Point still stands - it’s a major goal of building technology to mitigate the embodied carbon of buildings due to concrete.

danans4• 2 years ago

A big possible issue with this is that cornstarch (at least the way it's currently produced) has the same carbon footprint as portland cement, which it replaces in this process.

https://apps.carboncloud.com/climatehub/product-reports/id/7....

szvsw8• 2 years ago

The authors do mention approximately equivalent carbon footprints in their LCA, but they don’t really explain how they account for the energy involved in heating the corncrete. If they are assuming a clean grid or renewable source already, then there’s not much potential for reducing that carbon footprint. But if they are assuming a typical or dirty grid, then that’s one area where the footprint can come down a significant amount. I was only skimming but I didn’t see a mention of what assumption they used there.

danans4• 2 years ago

But if they are assuming a typical or dirty grid, then that’s one area where the footprint can come down a significant amount.

Not sure I understand how, since regular concrete made from portland cement does require heating to cure - in fact it's exothermic.

The vast majority of the emissions from traditional concrete come from the manufacturing of portland cement. It's not clear how a renewable grid would significantly lower the emissions of producing cornstarch, since the majority of emissions happen at the agricultural stage, via the petroleum based fertilizers.

scythe• 2 years ago

Before you get too excited:

- Global production of corn: 1.2 gigatonnes, source https://ipad.fas.usda.gov/cropexplorer/cropview/commodityVie...

- Global production of Portland cement: 4.1 gigatonnes, source https://gccassociation.org/key-facts/

And of course, cornstarch is only about 70% of the weight of corn. IIRC grain production statistics are usually by dry weight, but if we assume wet weight, it's even worse. Even if we completely obliterated the meat and biofuel industries worldwide, we would struggle to meet a quarter of the current demand for cement, which anyway is forecast to increase.

dylan604• 2 years ago

Here's hoping that corncrete doesn't interfere with all of that wonderful ethanol. /s

photochemsyn• 2 years ago

Portland cement is not easily replaceable in its main use (building construction) because concrete made with organic substances as sand grain binders, be it cornstarch or epoxy-polymer, isn't fire resistant.

The compressive strength of cornstarch concrete maxes out at 26 MPa according to the paper, while different Portland cement formulations range from 20-50 MPa, and epoxy-polymer can go up to > 100 MPa, though brittleness is a problem.

The optimal strategy for cleaning up Portland cement production is probably (1) renewable-based electrification of the kilns used to make CaO from CaCO3 (limestone), and (2) capture and stabilization of the CO2 from the kilns in a form like carbon fiber or diamond. Still a bit sci-fi but technologically feasible (but not economical at present).

szvsw8• 2 years ago

Another major area for decarbonization is also just better design - just by making it easier to fabricate and deploy shaped beams/floor systems which allocate material in a way that mildly follows the moment diagram, you can knock out massive amounts of emissions, just by virtue of the fact that the developing world will largely be building all floor systems out of concrete…

https://doi.org/10.1016/j.engstruct.2021.112955

notamy• 2 years ago

Under water submerged conditions (20˚C), hardened CoRncrete specimens showed partial to complete degradation within a day.

While this certainly isn't great for most obvious building use-cases, I wonder if it would have utility for ex. building a research base on the moon someday.

szvsw8• 2 years ago

I actually have some friends working on construction materials for moon bases! ie turning regolith into bricks, using drones/robots to assemble the structures etc. pretty cool stuff. There’s a fair bit of research going on into this problem.

I think the main challenge with your idea is that you have to get the corn starch to the moon… you really want your solution to be focused on ISRU (in-situ research utilization) as much as possible.

elif2• 2 years ago

It's a 1:5 ratio starch:regolith

I think you'll find that transporting the water is far more costly, which would be the case with any lunar concrete

Animats3• 2 years ago

This is much like staff.[1] Staff is a kind of cheap artificial stone, made from gypsum, cement, dextrin, and glycerin, with some long plant fibers for tensile strength. It was used for temporary exhibition buildings for various fairs a century ago. The Palace of Fine Arts colonnade in San Francisco, built for a 1915 fair, was originally made from staff. By the 1960s, it was a ruin. The current version is a full rebuild from 1974 in more durable materials.

There are more promising bio-materials for construction.

Attempts have been made to make boards from bagasse, the leftover fiber from sugar cane processing. It works, more or less. The most useful application for bagasse is making clamshell containers and plates for fast food. It's cheap, biodegradable, and non-toxic.

[1] https://en.wikipedia.org/wiki/Staff_(building_material)

yunohn6• 2 years ago

Sometimes I wonder if buildings really should last hundreds of years taking up that space. Similar to how laws last almost forever and lead to byzantine requirements and tricky interpretations.

Would be interesting if transient infrastructure and time-limited laws would lead to a more beneficial way of living.

Cthulhu_2• 2 years ago

Japanese buildings are designed to last about 50 years iirc, after which they're demolished. Temples are rebuilt every X years as well. The building materials, at least in those temples, are mostly natural (wood, mostly cleverly jointed so minimal metal required). IDK if they're still popular but the tatami mat is made out of rice straw, also fully biodegradeable (assuming the stitching isn't plastic).

jedimastert• 2 years ago

The question then becomes how do you make a building degrade in a way that isn't dangerous to the occupants? When a building does degrade, it takes more energy to remove the debris and build a new structure. Can that be minimized as well? This isn't to say I'm against the idea, just thinking out loud

Animats3• 2 years ago

No, just slums.

Tanoc2• 2 years ago

If buildings could be more easily repurposed this wouldn't even really be a question that needs to be asked. Throughout most of human history larger buildings were repurposed instead of being destroyed, because there wasn't an illusion of limitless materials and labour. The proliferation of specialized buildings after the late 1800s because of that illusion rising, especially for commercial interests, is one half of a problem. The other being regulations written for those specialized buildings that provide little or no possibility of being repurposed.

For example old roadside motels from the '50s and '60s could easily be remade into dorm style apartments with micro kitchens supplemented by communal bathrooms, but laws, especially hygiene and fire codes, currently prevent that. Those motels are built of sturdier materials than many modern homes, and only need to be refitted with fire suppression systems and heat pumps to be cheap housing.

Making temporary housing is just creating a new problem rather than solving an existing one.

Nasrudith• 2 years ago

Most of our infastructure would benefit environmentally if it was more permanent, not less. Roads in particular. Buildings seem to have side benefits from more permanent construction such as better insulation and disaster resistance.

Cthulhu_2• 2 years ago

They're building tall buildings out of "wood" nowadays, but it's so processed, sliced up, layered and laminated, and pumped full of epoxies that it's really more down to aesthetics than any environmental benefit; that is, effort / energy investment is high to the point where it's probably cheaper to make steel, and they're not biodegradeable.

bobthepanda• 2 years ago

There’s still some environmental benefit; wood is so much lighter than concrete or metal as a rule, that you end up needing not only less material in general but also less material in the structure because the frame weighs less and needs less support, not to mention general carbon savings from transportation of heavy material.

It’s also a major time saver since unlike concrete it doesn’t need to set, and the products are basically manufactured panels that don’t need specialized workers to install.

skybrian• 2 years ago

That seems rather long-lasting for a temporary building. I wonder what other buildings should be temporary?

Animats3• 2 years ago

That seems rather long-lasting for a temporary building.

By 1964, not much of the colonnade was still standing. This was all that was left.[1] What you see today is a full rebuild.

[1] https://www.sfgate.com/bayarea/article/Dramatic-Palace-of-Fi...

qup• 2 years ago

Do ants eat it? They eat some corn-based insulation I have.

elif2• 2 years ago

I'm gonna guess it's more likely that it won't last as a building material, rather than believe no one thought to mix sand, cornstarch and water until now..

ncphil• 2 years ago

Encouraged to see the skepticism here.

Recalling when, after years of hype, the demand for corn-based ethanol as a fuel competed with corn for food, leading to even greater food insecurity world-wide.

Grifter's gotta grift, but that doesn't mean their BS gets to go unchallenged.

metada5e• 2 years ago

Corn-based electrical insulators proved problematic in cars due to rodents eating the tasty insulators. Something to check in testing this material. Mycelium based construction materials may be more beneficial due to fire resistance, insulation and excellent R values and relative unpalatability. Ecovative is a good place to learn about this (no personal affiliations, just a fan.)

bfung• 2 years ago

HN meta: an actual research paper vs product posing as science. Nice.

a1371• 2 years ago

This is a thing not because it adds strength or sustainability. We produce way too much corn and they are looking for ways to use them up.

jxf• 2 years ago

Unclear on that first point. The authors claim 26 MPa for CoRncrete, which is about the same as the higher end of the range of concrete (~28 MPa) but much cheaper. On the other hand, it sounds like the paper's saying it's also much less durable.

LegitShady• 2 years ago

I wouldn't count anything under 40 MPA as "high strength concrete" at all. Thats where high strength concrete starts for me. High strength concrete mixes can go up to 180-200 MPA although thats some crazy specialty stuff for very niche uses.

25 mpa concrete is "i'm doing my driveway" concrete or "I bought a bag at home depot" concrete not high strength concrete.

elgenie• 2 years ago

Producing less corn rather than subsidizing it is the better way to go.

This just seems like another fake-green boondoggle, similar to ethanol.

gigatexal• 2 years ago

Full article here: https://www.sciencedirect.com/science/article/abs/pii/S09500...

major505• 2 years ago

please, let it be the registed commertial name. I would be awsome.

29athrowaway• 2 years ago

Topsoil is very limited, this seems like a bad idea.

otterley• 2 years ago

(2017)

dang• 2 years ago

Added. Thanks!

andai• 2 years ago

Does the polymerization prevent biodegradation (e.g. digestion by fungus)

I don't think I have access to the full paper, but it is described as biodegradable, which seems to be the opposite of what you'd want your house to be made of?

architango• 2 years ago

Siliation or esterization of the long carbohydrate chains would make them close to indigestible, and also far more water-resistant, but at that point the cost (including environmental) would outweigh the benefits over concrete.

mystified5016• 2 years ago

Ohio has entered the chat

zouhair• 2 years ago

Stop using food for anything else than food, people. We don't have enough arable land to waste on this stuff.

MBCook4• 2 years ago

We have enough food to feed something like an extra 1.5 billion people.

Fixing waste and distribution would more than make up for it, and that’s not including the possibility of shifting corn over from ethanol instead if this proves actually useful.

dukeofdoom• 2 years ago

Interesting, just watched a guy that turned cooking oils into plastic (with a catalyst like iron). And he got into how canola oil, was a rebranded industrial lubricant that needed a new market post wwII. (just with lowered toxicity levels)

"Seed Oil converts to PLASTIC"

https://www.youtube.com/watch?v=Ra_tCL5-4c0&t=1s

And earlier listened to Robert Kennedy on a podcast where he discussed how offshore wind farms, have turbines placed in the ocean with giant blades that can explode and pollute water with shards that close beaches and kill Whales. While significantly more expensive than terrestrial wind farms.

Public opinion is often swayed by such labels like "environmentally friendly", "reusable", "pro environment". Who could not support such things ... Turns out environmentally friendly products, often are just a swindle to get massive amount of subsidy money from government ... for bad ideas. It's a form of corruption, as politicians that approve these things often benefit in some way. While public loses.

DrNosferatu• 2 years ago

Won’t that compete with food production?

imtringued• 2 years ago

This is meaningless. Hempcrete or strawbale construction with a load bearing wood structure is more sustainable than this.

CoRncrete: A corn starch based building material (2017)

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