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:
> 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...
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.
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.
Having 'negative' results like this published is so good though because then it's harder to scam people with this idea in the future.
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.
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…
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 The Palace of Fine Arts colonnade in San Francisco, built for a 1915 fair, was originally made from staff.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.
That seems rather long-lasting for a temporary building. I wonder what other buildings should be temporary?
> 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...
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.
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.
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.
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).
Japan is not in the same era as what you're describing.
There are many modern buildings that are built the same way as other modern cities and designed to last.
They have very modern infrastructure, and while what you're describing does exist, but is by no means the norm nowadays.
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
I was thinking less about potential energy usage / emissions, so that’s a good point. Probably solvable like the sibling comment about Japan.
I was philosophizing more about changing the way we enforce permanency of decisions taken by humans who lived before on everyone who comes after them.
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?
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....
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.
> 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.
I love the name.
EDIT: to make this comment a little less useless: here's Jonathan Davis performing for The Queen of the Damned movie. The official soundtrack release includes different performer's vocals. Davis had a contract at the time, which allowed him to sing for the movie, but not on the oficial OST release.
Full article here: https://www.sciencedirect.com/science/article/abs/pii/S09500...
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.)
> 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.
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.
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
Makes sense!
HN meta: an actual research paper vs product posing as science. Nice.
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.
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.
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.
This has been out for quite a while, there's even a YouTube video from 2015 showing how to make it using a microwave.
They mix 225g sand with 50g of corn starch.
It's more "sand based" than "corn based".
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.
All concrete is more aggregate than binder… but it’s the binder that matters from an emissions perspective.
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.
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..
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).
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…
Topsoil is very limited, this seems like a bad idea.
please, let it be the registed commertial name. I would be awsome.
Do ants eat it? They eat some corn-based insulation I have.
(2017)
How does it handle water?
Perhaps they have to seal it so water doesn't get in.
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.
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.
Here's hoping that corncrete doesn't interfere with all of that wonderful ethanol. /s