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Ferrock: A Stronger, Greener Alternative to Concrete? (buildabroad.org)
161 points by vezycash 3 months ago | hide | past | web | favorite | 87 comments

This reads like an advert. The whole "carbon-negative" thing relies on the assumption that steel dust is a waste product, which seems highly dubious to me. Steel is commonly recycled, including steel in very small pieces such as machining chips. It's hard to believe that anybody producing steel dust in quantities sufficient for use as construction material would just throw it away. The fair comparison would include the energy needed for steel making, which needs even higher temperatures than the "staggering 2,800 degrees Fahrenheit" needed to make cement.

Yes. It checks all the green boxes (CO2, Native American nations, EPA, etc.) but not the structural engineering boxes. Now if the tensile strength were 5x greater, that would be something. An alternative to concrete with rebar would be useful. Rebar corrosion is a huge problem and the limiting factor on the life of modern concrete buildings.

Some way to use up recycled glass cullet has potential. There's a glut of that.

Basalt rebar looks pretty good. It's too new to be in wide use yet, and prices aren't lowered by wide use either. Non corroding, though.

They do mention that it is less brittle (more flexible) than concrete. This would mean that less cracks might form, which would be very helpful in increasing rebar lifetime.

My first thought when I read it's more flexible was that this would be applied to road surfaces where crack prevention was the only way to prevent damage from weather. I agree, though this is also clearly an ad =)

Wasn't CLT supposed to be the green answer to concrete?

One problem with Roman concrete is the very long curing time, which makes it less suitable for very tall buildings, because they require that the lower floors are almost fully cured before the upper floors are erected above them.

Yep. The article compares it throughout to cement instead of to concrete. People don't build large structures out of cement. Is it supposed to be used as binder to replace cement in concrete? Or is the comparison to cement simply more favorable than if they made a realistic comparison to a functionally similar mix of concrete?

Much (most?) concrete construction already includes steel in the form of rebar. It's not clear how much this new process uses compared to traditional concrete. Or if the fact that steel dust can be used versus rebar represents a carbon advantage.

We'd have to see a fuller lifecycle analysis of a variety of construction scenarios.

That was my view too whilst researching the subject. The only information I could find on Ferrock was very hopeful marketing material.

We need new materials here urgently. Ideally something which, like plants, would pull the carbon from the air during the curing process. Whoever creates such a material is going to get very very rich..

They linked out to a company called IronKast as an example of commercial development. The site isn't encouraging: http://ironkast.com

Low grade iron scrap can probably be diverted from landfill, or reclaimed from it?

Low grade iron scrap goes to Nucor Steel. Nucor started in steel making rebar from scrap. Then they figured out how to continuous-cast better steel from scrap. Now they're the biggest steelmaker in the US. If it's steel or iron and you can get it to a scrapyard, it's going to be recycled. If it was a car, it's going to be recycled. If the magnets at the recycling center can pull it out of trash, it's headed for a steel mill.

Iron and steel are not normally put in landfills. Due to the ease of extraction, iron is the most recycled material on the planet.

If people don't do this already, the technology to do it cost-effectively probably doesn't exist.

Yes, I’m pretty sure you could make cement from waste clay as well...

Also wouldn't steel make the concrete less effective over time as the steel rusted and made the concrete weaker?

The article claims that the steel rusting is actually an integral part of the process. The iron in the steel reacts with CO2 to rust, which sets the material.

I actually read the carbon negative claim as implying they're forming an iron carbonate. I'm not sure why it would be carbon negative if it's just iron to rust, rust doesn't have any carbon in it.

Watching the YouTube video (mentioned further down) which covers in-development concrete alternatives (https://youtu.be/wOE4UegzJ_M?t=190), apparently this forms FeCO3 + H2.

The C in that would be the carbon sequestration. :)

Without commenting on Ferrock's merits, I want to say I'm glad every time I hear concrete/cement's CO2 impact addressed. I feel that should be a MUCH bigger part of the conversation about any kind of construction as we look towards very sharply curbing emissions over the next decade.

For example, "the wall". Obviously advocates of the wall for the most part don't give a crap about the environmental impact. But even on the Left I don't hear this cited often as a reason to oppose it (amongst many). The CO2 emissions from constructing a several hundred mile long concrete or steel border would be enormous. (Steel is also a major emissions source.)

Even urbanists, who generally talk a lot about denser construction as having environmental benefits and are kind of "lefty", don't generally talk about the counterposing cost of concrete & steel emissions. I'm not saying it doesn't pencil out, but let's please always talk about it.

> " The CO2 emissions from constructing a several hundred mile long concrete or steel border would be enormous. (Steel is also a major emissions source.)"

You probably don't hear this approach taken very often because most people won't consider it persuasive when they remember that we have nearly 50,000 miles of interstate highway and many many times more miles of lesser highways and roads. The concrete and steel needed for a couple hundred miles of wall would be a drop in the bucket of infrastructural concrete and steel across the country.

You can of course argue that every drop counts, but that sort of argument isn't going to impress many people, which explains why you don't hear it very often. Arguments against the necessity of the wall have more bite.

> The CO2 emissions from constructing a several hundred mile long concrete or steel border would be enormous. (Steel is also a major emissions source.)

This might still be worth if it prevents illegal migration of 1 million people per year from countries with much lower CO2 emissions per capita (e.g. Venezuela 6t/year) to the USA (16.5 tons/year).

http://greennews.ie/carbon-footprint-of-trumps-proposed-us-m... estimates the carbon footprint of the „Wall“ as 48m tons - once. With my simplistic numbers above it saves up to 10.5m additional tons per year (i.e. N times that amount in N years). So its carbon footprint is amortized in less than 3 years.

That said, I have no political opinion about the „Wall“ (being in Europe), I just like analyzing both sides‘ arguments.

That assumes that once anyone enters the US, they will, on average, produce the same amount of CO2 emissions as present US residents. That seemed dubious to me... so turned up this: https://cis.org/Immigration-United-States-and-WorldWide-Gree...

> The estimated CO2 emissions of the average immigrant (legal or illegal) in the United States are 18 percent less than those of the average native-born American.

> However, immigrants in the United States produce an estimated four times more CO2 in the United States as they would have in their countries of origin.

So I suppose the overall logic still holds, just slightly adjusts the math.

The thing is, at the end of the day emissions are global - We all share the same Earth.

I love this counter-intuitive thinking.

A while ago at dinner a friend said she was trying to do the right thing environmentally, but it was just too complex. (The case in point was her wanting an EV but hearing that while the car would be clean, there would still be emissions back at the power plant producing the electricity - true in many places but not in my country which has around 78% renewable grid energy).

Your comment clarifies just how very complex it is understanding the overall impact on the environment of our actions.

(No comment on whether a wall would actually prevent 1M illegal migrants a year).

I just read this as "The trump border wall will be good for the environment because individuals from a low pollution country will not start polluting at the same rate as Americans."


Not quite. They said if it prevents 1M immigrants.. a pure hypothetical to explore the math of discouraging American lifestyles. They definitely did not say the wall would succeed in preventing 1M/year from entering.

That is absolutely absurd as only 190K/year cross that border illegally to begin with.[1] Most undocumented immigrants in the US enter legally and just overstay their visas.

[1] https://qz.com/1525779/how-many-undocumented-immigrants-cros...

Specious argument.

1. It assumes that each immigrant’s carbon footprint will suddenly leap to typical American consumer levels. But desperately poor immigrants are likely the lowest producers of emissions. Thus, admitting more would actually lower America’s per capita carbon footprint.

2. Addendum: This "1M/year kept from entering" hypothetical is utterly ridiculous to begin with. Even if the wall was 100% effective -- which is absurd given it can be climbed over with a ladder or tunneled under -- only 190K/year cross that border illegally to begin with.[1]

[1] https://qz.com/1525779/how-many-undocumented-immigrants-cros...

In other words, according to your data/assumptions the amortization time is just longer by a constant factor (unless you mean to claim that the wall would be completely ineffective, which is absurd and needs more proof than „I believe it can be climbed over using a ladder“). I don’t disagree strongly. The point that a single, large CO2 emission „investment“ may be worth it, still stands.

So if a wall with a “carbon footprint close to Ireland’s annual CO2 emissions” keeps out just one more immigrant/year, your point “still stands” and it’s just a matter of “amortization time.” Your reasoning here is about as sound as your mischaracterization by a factor of five of the number of immigrants crossing illegally.

It will need maintenance though, as it will be continuously attacked.

And what is absurd about an unguarded wall being very ineffectual? As an obstacle it represents a rather modest practical challenge compared to walking the length of Mexico for example. A tall enough ladder isn't a very exotic object, and rudimentary training of its handling will be provided by the same people who teach how to cross the desert.

So putting up a wall on some parts of the border makes it not worth the the effort and risk of crossing at those parts, but if you put it up all over the border you only modestly increase the total risk.

Responding down here so as not to derail your otherwise strong comment, but I was bothered by the part that read "Obviously advocates of the wall for the most part don't give a crap about the environmental impact." This might be true on average, but not universally, and I don't think "obviously". I'm not personally an advocate for a wall, but I have pro-Trump relatives who would respect the environmental argument, particularly regarding animal habitat. I think it's a matter of weighting different priorities, rather than "not giving a crap". If all else was equal, I think many advocates would be happy using environmental impact to decide between designs.

Didn't say it was universal.

I'm confused by your last point. Are we to assume that people living in denser constructions would otherwise have lived in grass huts? Or, less ridiculously, only pre-existing buildings? I would imagine that the alternative between people living in new apartments in a dense area would be sprawl, where they would instead live in new houses, which are going to (per person) have much higher amounts of concrete and steel used.

Dense urban construction typically uses more concrete and steel. New homes in low rise areas can be built mostly out of wood, for example.

Not saying sprawl doesn’t have its own impacts, just that we should properly account for the footprint of concrete and steel construction.

As an “urbanist”, the kind of “dense urban construction” I would like to see is (some proportion of the) suburbs currently full of single family detached homes on large lots replaced by 3–6 story timber-framed apartment buildings / condos near transit and zoned to allow ground-floor retail. Ideally with narrower roads, fewer parking lots, more public green space, and more land outside of cities left as forest.

Many of the densest neighborhoods in the world have no buildings taller than 5 or 6 stories.

But I would be surprised if a 40-story apartment building and the infrastructure to service it required more concrete than housing the same number of people in a low-density suburb. Consider all of the sidewalks, sewers, parking lots, concrete foundations, elevated highways, bridges, .... involved in building and servicing a low-density car-commuter neighborhood.

The “one plus five” buildings you’re talking about typically have concrete first floors.[1]

You make good points about sidewalks etc. but at the same time that stuff needs to be built bigger and stronger and renewed more in dense urban areas. All I’m arguing for is let’s run the numbers. Don’t just assume city living is more ecological because it’s denser.

[1] http://archplanbaltimore.blogspot.com/2015/03/how-one-plus-f...

The technology now exists to construct buildings in excess of 80 meters entirely out of wood.

With that in mind, it's now possible to construct dense urban areas without relying on carbon-emitting concrete or steel going into the structure. Only wood, which is a carbon sink and can be sourced sustainably.

Given that this is fairly well-known - and that the impact of concrete on the environment well-studied - what is it that leads you to think that the numbers have not in fact been run?

I would not say any of that is fairly well known. Nor that it’s clear whether you’re claiming the general consensus urbanist vision is all wood, or that it’s concrete but the emissions are ok because they’ve been “well-studied”.

I'm imagining that there's an element of truth to what you say - but one would guess that the slabs for these houses are still made up of concrete, not to mention the driveways (as well as all the other infrastructure running to said houses - sidewalks, curbs, etc). Apartments being smaller, I would be surprised if there's a huge difference in materials and construction energy input per capita between apartment living and house living. The economies of scale of an apartment building are pretty big; for example, it has one roof and one slab (obviously way bigger).

It's of course possible to construct all sorts of weird versions of this comparison (tiny houses vs McMansions, ultra-modern mid-rises made from timber, etc. etc).

I suspect it's all moot given that transport is such a substantial component of energy use and these houses/apartments should last a long time.

Lower/moderate density could still mean apartments, just constructed without much concrete or steel. You don’t necessarily neeed concrete slabs with smaller buildings. Transportation could be solar powered. It’s at least plausible that moderate density villages networked by sustainable transport could be more ecological than high density concrete/steel structures.

All I’m saying is I don’t hear urbanists talking about the carbon footprint of construction. It’s like an article of faith that high density is ecological.

you're not including all of the concrete to pave the roads, sidewalks, etc to get to that sprawl. Nor all the plastic and sh*t used on siding suburban houses. Nor all the malls and other sprawl buildings which are also, by code, required to use steel studs and similar construction to dense urban environments. Nor all of the gas / carbon involved in all of the in-efficient travel in those locations.

Eg just becuase it's short doesn't mean it's efficient, and tall doesn't mean inefficient.

What it means is we're all just arguing based on no data and instead preferences.

All good points, but none of us are arguing for doing things they way they’re done now. My question is what we should be aiming for. Is it greener to build max density, given the strength required for those buildings (as well as the transport of food, water and resources into cities)? Or is it greener to build moderate density towns that can be constructed from greener materials and co-located with food and water sources? (Not necessarily single family homes and suburban sprawl.)

I would think the goal is to provide the most efficient building in the places people are providing needed social and economic value. Not to force people into the most efficient space possible. So you're going to have different answers where different climates, industries, and needs are present.

Hyper density isn't going to work in rural/farm/resource areas where people essentially need to spread out. Nor does super low density work where everyone essentially comes together to do things.

In the end I think you need to assume that all of the arrangements exist for a point on the multi-variate optimization curve, and just figure out commonalities that make them all more efficient overall, instead of re-aligning all living on a current single local optima.

That’s easy then. Add a carbon tax and the market will adjust accordingly to the costs.

Unfortunately politically it’s not so easy.

Bringing up the wall here is a weird argument. It's sufficiently awful on so many levels that emissions are the least of our concerns.

>David Stone

Nice Aptronym there


Thanks, the list of people with aptronym names was fun to read and the section about inaptronym names was even better. I read them aloud to one of my flat mates and we had a good laugh.

I just saw something in one of those websites with overloaded side columns that had an article about a UK police officer named Rob Banks.

That's... hi-larious. Favorite from the Wikipedia names list: Don Black - white supremist.

TIL - aptronym

I sense reference to David vs Goliath

I’m not sure why the article calls CO2 C02, did they just think zeros look better; it makes you wonder about the article.

Are typos a known issue in searches? 1, I, or l, 0 and O


Looks nice but I really wonder about its chemical properties over the longer term, and its other unexpected behaviours (how does it react to electrical discharge? fire? extreme cold? acid rain?).

I'm curious how the patent will impact it's adoption. Was regular concrete patented when it started to be used? Depending on how strictly he enforces it, this could easily prevent Ferrock from becoming widespread.

Did a quick google on patents in this area and there are MANY! And, Thomas Edison even had concrete patents http://edison.rutgers.edu/cemepats.htm


The B1M YouTube channel recently made a video [1] covering concrete alternatives (Ferrock, Biomason bricks) and solutions for injecting CO2 into concrete (CarbonCure). It's really interesting.

[1] https://youtu.be/wOE4UegzJ_M

There are a lot of other portland cement alternatives that are not exploited despite being very cheap.

There are literally mountains of flyash laying around in Europe without anybody wanting to use them for concrete.

> While the material composition and implementation techniques have already been tested at the University of Arizona, IronKast is currently in the process of commercializing the Ferrock patent and implementing it into pilot projects within marine environments.

So, in other words bought and paid for by the taxpayer, and sold to the highest bidder on the commercial market.

So much for encouraging use of this stuff. It'll be priced right out of the market because it's "green".

> So, in other words bought and paid for by the taxpayer, and sold to the highest bidder on the commercial market.

Yes. And why this has become common practice might surprise you.

Universities used to try to open technologies up to anyone who might want to use them. Cool new thing, come use it, free to all humanity! Problem was, for the most part nobody wanted the free thing. University outputs typically require some non-trivial amount of investment and work to actually be commercializable, and few companies want to invest when they can't know they'll get a commercial advantage over the competition out of it.

Selling it on the commercial market, on the other hand, accomplishes two things. First, it puts some money back into the university, which might allow for more research for the taxpayer dollars (cool, right?). Second, it offers improved chances that the patents might actually turn into real stuff now that the owners of it have both a commercial interest and temporary exclusivity.

I wonder if it could be made at a reasonable cost at global scale.

I wonder if this ferrock would have undesirable qualities when interacting with radio signals and electronics.

Accidental faraday cage? :)

Isn't the mercury produced by cement manufacturing a more urgent issue than its CO2 output? CO2 is being attacked on many large-scale fronts, but last I checked the mercury in the oceans rendering seafood unsafe to eat was largely put there by the cement industry.

The high temperature needed for industrial processes like making concrete is a perfect fit for concentrated solar furnaces. That's because there is a thermodynamic loss in taking heat energy to another form like electricity and back again. That's why natural gas heating is roughly 2-4 times cheaper than electric heating. I don't understand why every factory in the world doesn't have one of these attached to it to save close to 100% of their fuel costs for 4-8 hours of the day:


Some formulas on concentrator efficiency:



(PDF): http://www.desware.net/sample-chapters/d06/e6-106-05.pdf

(PDF): https://core.ac.uk/download/pdf/82769819.pdf

It looks like the highest temperature achievable for a trough-shaped solar collector is about 400 C, whereas for a parabola, it's closer to the temperature of the sun (at least 2000 C). Note that the maximum possible temperature achievable for any concentrator is the temperature of the source, by the laws of thermodynamics:


I don't have time at the moment, but maybe someone could derive the maximum temperature for a parabolic trough? I feel like it might be approximately the square root of a parabolic dish, but I don't know for certain.

I could put together buying ferrock in large quanties (over $1 million) because of the many bike paths and greenbelts that still need to be poured along the river, canals and train tracks in my city. But using concrete or asphalt is perhaps too environmentally unfriendly, and I haven't found a good alternative (say pavers) because we still want people to be able to skate and have a comfortable bike ride. We also have football field-sized piles of glass bottles waiting to be recycled that would be another free input along with solar heat.

What are you going to make your crucible out of that is transparent, won’t contaminate the contents and is strong enough at high temperatures to withstand regular use?

Also if it wasn’t available 20 years ago there’s your reason.

My first thought was maybe silicon carbide, since it can be made with readily available silicon and carbon. But there are other caramics which have much higher melting points. Who wants a little hafnium carbide at 3958 C haha:


I'm having trouble finding infrared conductivities:


So looks like aluminum nitride might be best (first made in 1877 so we have the technology!) with a melting point of 2200 C:


Portland cement (the basic ingredient of concrete) is made at 1450 C:


And looks like any aluminum from the crucible wouldn't contaminate the concrete. Not sure about the nitrogen, but since the air is nitrogen/oxygen, it should be ok:


But I think it's important to flip the problem on its head. Since solar thermal energy is essentially free after the solar furnace is manufactured, then we might as well scale it up to provide 2-10x more heat than we need, and then choose a ceramic with the material properties we want, even if its thermal conductivity isn't as efficient as we'd like.

Keep in mind that any heat we get from this will be roughly 4 times cheaper than from photovoltaics (running at 25% efficiency) since we avoid the light->electricity->heat conversions.

You seem to have a fundamental misunderstanding about how crucibles operate. The outside of the crucible is not supposed to get particularly hot. Heat is applied to the inside; the crucible contains both the material and the heat.

If you don’t do this then all the air in the room is also heated up to ludicrous temperatures, and that tends to be bad for any other equipment or people nearby.

but we have more sand than iron-dust, no?

Good question. I know for a fact that the type of sand is important, specifically that the shape and grain of the sand required for concrete makes a lot of readily available sand unusable for concrete.

As for iron dust, I have to agree. The only way I could see iron dust being practical is if this tech was able to repurpose industrial waste (rusted up sheet metal, old rebar, etc).

From the article:

> It’s actually created from waste steel dust which is normally discarded from industrial processes and silica from ground up glass. The iron within the steel dust reacts with C02 and rusts to form iron carbonate. It’s this that is fused into the matrix of Ferrock and, like concrete, after it’s dried, it cannot be melted back into a liquid form but retains its hard, rock-like qualities.

> ... But there’s skepticism from the cement industry that while Ferrock could be great for niche projects, it isn’t practical for large-scale industrial use, like highways for example. If steel dust suddenly goes from being a “waste” material to a highly-prized building resource, it’s price will increase exponentially and the costs of producing Ferrock may limit its application.

Well, just don't switch iron/iron oxide dust for aluminum dust...


I read that the Sahara is useless, for example, because desert sand is rolled rounded. The only sand that concrete can use is the dug up, sharp cornered kind.

I wonder if it's possible to "roughen up" smooth sand for this purpose. Shoot it against itself in a special machine, thus breaking it to smaller, sharp-edged pieces... or something.

"Large Saharan Collider – not what you think it is!"

Concrete "sand" is made by smashing quartz into tiny rough bits.

I heard that there are more stars in the universe than grains of sand on earth, so we could use stars instead..

Have you tried mixing stars and water together?

I believe that's the recipe for the Philosopher's Stone, from the old books.

That's why the Middle-Age alchemists couldn't make one.

Now we can.

Perhaps that’s how the sauna was invented

You're forgetting that it's easier to create rock dust from scratch than it is to create iron dust from scratch. That's important when you're comparing the two, since you can't simply scoop up iron dust off beaches and river banks anyway. Given the choice between manufacturing rock dust and manufacturing iron dust, the choice is obvious.

To manufacture rock dust you:

  1. Quarry rock.
  2. Pulverize it.
To manufacture iron dust you:

  1. Quarry ore.
  2. Pulverize it.
  3. Smelt it (which requires coke, a basket of worms in itself.)
  4. Cast it.
  5. Grind it.

We may be running out of suitable sand to use for concrete, but that doesn't mean iron dust is more abundant.

Looks good. I wonder if is color fast for lack of a better word. Would it cause stains?

5 times harder.. superlative concrete?


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