I'd long been part of the camp that says "on the whole, concrete's not that great of a material to build with, for a bunch of reasons, but it's also got some significant upsides."
Then, I stumbled backwards into this crazy building technique that solves _some_ problems really well.
It's this traditional building technique called "rammed earth".
It's updated a smidge for modernity, but it's basically the same today as how buildings were built 1000 years ago.
Mega beautiful, practical, interesting constraints and opportunities, anyone can build them, etc.
> Video from a skilled modern-day rammed earth structure builder
Note that the rammed earth there is being mixed with cement, making it in effect a lean concrete. Additionally, the column (?) is on top of a concrete footing, it appears from coloration to be a fairly normal concrete mix at the bottom, the top layer is also definitely a standard concrete mixture, the rebar looks like standard for something in a short building as that presumably is. Essentially the only difference between that and a standard concrete structure is that the column has to be much larger in cross section (as the lean concrete mix used would have lower compressive strength than normal concrete), the mixture uses less cement in exchange for compaction in lifts (i.e. exchanging material cost for labour cost), and the formwork has to be much heftier to sustain the pressures being placed on it from the pressure rammer.
I quite like the sturdier looking columns, and the layering is quite attractive (that guy clearly puts a lot of effort into it, visible when he's fine tamping the outside edge of the layer very carefully), but I don't think it's so much different than normal concrete. Trying to do QC or QA on that mix design would be a nightmare.
I think cob (think hobbit houses), similar, has been around longer. And there are examples of cob buildings lasting hundreds of years. I wish building code would let me get some friends together for some house sculpting . . .
I've had the fortune of checking out a few rammed earth structures around BC, Canada (there is a cool fence/wall built with it within a property on Saltspring Island, a winery's sales building on Hornby Island, an amazing example in Osoyoos[1], and many more) and I agree, it's really beautiful.
If I have the opportunity I'll almost certainly use it to build a home in the future. I'm always excited when I see buildings using it. Well done rammed earth walls are absolutely stunning when finished properly.
Do you know how labor compares to more conventional methods? My understanding is that labor is often the biggest expense when constructing in America.
I wonder how difficult rammed earth would be to standardize. The Wikipedia article emphasizes customizing soil makeup to the local conditions and mentions the need for an expert to manage quality control. Basically I wonder how resilient rammed earth is against contractors cutting corners.
I don't like this trend of piling up unrelated green house gas contributions, particularly for a relatively small (8%) of the total of anthropogenic climate emissions.
For example, of that 8% figure 40% is fuel used to heat the kilns which make cement - i.e. a substituteable energy usage not unique to the cement industry. 10% is the fuel used to mine and transport the raw materials (also substituteable and not unique to the industry).
About 50% of emissions overall are from the actual calcination reaction of limestone[1], but plugged into that number it would then be that 4% of global emissions are from a non-replaceable operation in making cement.
That itself is also a bit a misnomer of course - aging concrete structures re-absorb CO2, up to about 40+% of that released during their manufacture over their lifetime.[2]
This is certainly not a process we couldn't manage by CO2 scrubbing or sequestration activities during the manufacture of cement, or you know, probably could offset with forestation projects.
All the rest of contributions are not cement industry problems, they're technology problems which if solved would change things positively for every industry (i.e. electric/microwave kilns, electric mining and transport vehicles).
and I consider it to be required reading for people outside of the field on the topic of concrete emissions. Globally, concrete production emits like crazy but this is largely a product of scale; other building materials emit far more GhGs by mass and volume but are used in much smaller quantities than concrete.
I'm all for a broad package of carbon taxes to both reduce growth and force the development of political and financial solutions for a low-growth, steady-state or degrowth economy but don't be misled into thinking the end result is a smaller share of concrete as a building material. More likely, carbon taxes will reduce the proportions of plastics, steel, aluminum and glass in construction in favour of more concrete.
On "we have to build differently with concrete": one promising development is carbon fibre reinforced concrete (https://www.compositesworld.com/news/carbon-fiber-reinforced...). Since most of the cement in conventional concrete is actually needed to protect the steel reinforcing rods from corrosion (and parts of the structure have to be stronger to support the rest of it), structures built with carbon fibre concrete can be much lighter and therefore use less resources. And because of that, it might even become cost competitive despite the higher price of carbon fibre.
But the "...or abandon it altogether" which someone left out of the title should be considered too.
Interesting article. Since the article focuses on Switzerland and I live there I have another angle to present that I find very interesting.
In our local region one problem is that the 'city' is heavily concreted. There's a distinct lack of green in many areas. In the summer and in particular this year, but other heatwaves as well, this becomes punishing in the city: concrete absorbs the heat during the day and radiates it at night, making the city even hotter.
See the sibling comment about whether the CO2 numbers make sense, but I also think with warming environs locally we're going to have to get a lot smarter about how we build to manage heat as well. There was a fascinating article on HN a while ago about the London Underground and the troubles they're having cooling it... The Swiss build a lot with concrete in their cities and there's going to be a corresponding difficulty of keeping them cool.
Traditional masonry construction has the same results in terms of thermal mass. More so, if it's denser and thicker. With the right shading and ventilation it's useful for both temperature extremes. See vernacular architecture in warmer/more extreme climates, or what Federation Square in Melbourne achieves with concrete:
Considering active heating/cooling as well as passive, the more thermal mass we have in buildings, the better they can act as thermal batteries for surplus renewable energy.
I'll add, there's some fascinating stuff towards the end, like this:
> Block went for a walk on top of the vaults [Kings College Chapel in Cambridge]. “In thickness-to-span ratio, they were proportionally as thin as an eggshell. They were so thin I could feel them vibrating. When I jumped, I felt them bounce. And yet they were still strong and standing. When you have an experience like this, and really feel how exceptionally thin this totally unreinforced structure is, it really motivates you. You realize: Damn, we have forgotten something. We have forgotten this knowledge.”
Not to be that guy, but the most efficient solution to this is a carbon tax. Once there is a carbon tax the market will be incentivized to pick the most environmental solution (keeping in mind we can pull this carbon back out of the air if we really need to). It would make a huge economic incentive to invent low-carbon concrete, for example.
I'd prefer that governments invested directly in carbon sequestration, and climate change mitigation if necessary, as well as sensible nuclear and renewable energy. Carbon tax is artificial, unsustainable, bureaucratic, and ripe for gaming. Accepting that CO2 production is for now a shared burden of modern life and working to mitigate it, rather than setting up some wealth distribution scheme, is more realistic, and more likely to succeed imo.
If you want to incentivize carbon capture you shouldn't focus on PLANTING trees (it's automatic - trees can plant themselves perfectly well without us).
The reason there are no trees somewhere is never "nobody planted them". It's either "somebody cut them and does something to prevent them growing back" or "the land isn't good for trees".
So planting the trees is never the solution. Buying farming land and reserving it for forest (that will grow by itself) is much more efficient.
>Carbon tax is the least bureaucratic and hardest to game mechanism.
Do you really think that in a world where every law is rife with carve outs and loopholes for specific industries, a world where states peddle liquor and gambling because sin taxes fund things they like, that a carbon tax would not be gamed? Of course not. The societal cohesion and political process to produce results that are not highly gamed, tilted or rigged simply does not exist, or at least it doesn't exist.
Your opinion that a carbon tax will "just work" in reality as it does in theory is predicated on sufficient amounts of ignorance that the distinction between ignorance and malice is no longer meaningful.
If you were king, I'm sure the carbon tax would be efficient, simple, and fair. But we live in representative democracies beset with special interests and ulterior motives, which means any carbon tax that our systems of government would actually end up implementing would not be efficient, simple, or fair.
I think you're underestimating just how badly a carbon tax could be implemented. If you don't account for the carbon emissions of e.g. imported goods, or carve out enough exceptions for specific influential special interests, you just end up accomplishing nothing other than regressively taxing the entire population.
The government is going to screw up anything they touch. So yes they'll screw up the carbon tax, but that's also an argument against any other measure they take to address the climate crisis. The carbon tax is more efficient than any other proposed measure, so you have to argue that they'll screw up the carbon tax more than they'll screw up the other stuff.
> you just end up accomplishing nothing other than regressively taxing the entire population.
Pick one. If it accomplishes nothing, it's not an effective tax either.
I posted at the top of this thread. Just want to clarify that I don't advocate for "incentives" like carbon credits or something, I advocate for government treating carbon removal as infrastructure, the way we build roads etc
I agree; I think it's better to just enact some sensible regulation. A carbon tax isn't going to magically produce more carbon-free energy (solar/wind/nuclear); only regulation can improve that situation.
> There won’t be a single perfect solution to the problem of concrete. One potential advancement is green concrete, which is decarbonized by changing the recipe, production process or longevity. Another is to capture emitted carbon at cement plants and store or reuse it.
Scroll down to the bit about ETH Zürich's research and there's some interesting stuff beyond the long opening about history.
> Block’s early research was focused on heritage architecture — vaulted cathedrals and other historic structures. “Our modern engineering tools are quite inadequate in explaining how safe these buildings are,” he said. Sometimes, he went on, digital engineering models of old buildings concluded that there should be no way they could still be standing, that they should’ve collapsed centuries ago. But there they were, solid, unmoving. Maybe, Block thought, there was something wrong with the models.
Any kind of physical model that is computable must make huge simplifications by ignoring most characteristics of the modeled system.
Therefore whoever creates the model must choose a priori which features should be included in the model, because it is believed that they influence the results. and which features should be ignored, because it is believed that they have negligible influence.
Any kind of physical model must be validated by comparison with experiments.
It is extremely frequent to discover that the model does not match the experiments, which means that the a priori judgments about what can be neglected have been wrong. In such cases, the assumptions on which the model is based must be reviewed and some of the decisions about what features should be included in the model should be reversed.
This is the normal way of working with any models, so the fact that the first attempt of modeling the ancient vaults has failed, does not say much, except that those who had made that initial attempt either did not understand well the behavior of certain rocks under compressive stresses, or they did not understand well how the building techniques used by the old masters redistributed the stresses in the rocks composing the vaults.
The article does not explain which was the problem with those wrong models, but then it mentions that the team of Block has applied the traditional method of stone masonry, of making structures which are under compressive stresses, instead of bending stresses, like in a flat floor or ceiling, to design floors that need much less concrete than the conventional floors.
This seems like a very obvious method, which should have already been used if good, so I wonder if the comparison about the concrete consumption was made at equal usable interior spaces. The main reason why flat floors and ceilings have been preferred in modern multi-level buildings was to provide interior spaces that can be completely used, without being partially blocked by structural elements (e.g. if the ceiling is a vault, you cannot put at a wall a cabinet raising up to the ceiling, but only up to the height where the curved part of the vault joins the vertical walls; if the vault has ribs, those impose additional constraints).
So I feel exactly the opposite, yet having nothing to do with climate denial. I should state that my experience with government lies exclusively with the US, so that should be taken into account to understand much of why I feel this is an approach that would result in an outcome that's the opposite of what is desired.
Let's ditch "the thing" -- "Carbon Tax", because "the thing" has certain assumptions behind it -- like political party X or Y believes or is skeptical of climate change/carbon taxes/etc. So I'm going to just call it a Concrete Tax. You can make the connection that it's a carbon offset, is way more sophisticated than a tax ... For most citizens, "Concrete Tax" is how it's going to be experienced/understood, anyway (and for a lot of them, that might be a good thing if you support the tax).
So we start at "Government applies or increases the tax levied per (unit) of (concrete) sold (at specific supply chain point)." Your problems begin with the things in parenthesis, but let's say you've gotten them right. The arms race begins.
It isn't this simple, but as it relates to this topic, it's good enough to think of "a cement business" as a for-profit publicly traded company who -- like every for-profit publicly traded company -- has a responsibility not to keep the customer happy, not to make good products, not to help the environment, not to make the C-level executives or the employees wealthy or really do anything other than "to make money for its shareholders (owners)".
The goal of the government by levying a "Concrete Tax" is to coerce the corporation into altering its behavior -- either replacing "concrete" with "green concrete" or using something "more green", entirely -- by increasing the cost.
First, you have to look at the market. Advances have been made and are being made in to make concrete more green, more durable, and superior to other products for more purposes (both in durability and environmental impact). Really, you're seeing a diversity of products that trade-off different strengths and fit better for narrower purposes. The article didn't conclude that "things are A-OK" but reading where things are and understanding that "the pace of technology is always accelerating", we can expect that "left alone we'll have better products, anyway". Apply the tax and "the current producers" start to consolidate. It's likely the next product isn't "I Can't Believe It's Not Concrete", but rather "Concrete 2.0 -- twice as strong with 10% of the Carbon!" It's possible you make it hard to enter the market to "provide a solution" because of the closer association of the hypothetical "Concrete 2.0" and the cursed/taxed Concrete.
Once the "arms race" begins, the taxed business is rarely left with "do what the government wanted me to do". Frankly, they didn't just come out and ban it, they went the subversive route by applying a fine (sorry, tax) to the product so it's hard to judge them for not playing by the same rules. They'll start poking at "the definition of concrete"; the exclusive goal being to find "something that is taxed less" with "how well it appears environmentally" being one of many (and only as high as it must be) variables ranked according to cost/need. The common approach is to move the problem somewhere else in the supply chain where people aren't paying as much attention (kick the can down the road).
The "avoid the tax by importing it" approach is a favorite. This usually falls into the pattern of "this or that trade agreement forbids the US from taxing the imports, so we'll just stop making it over here and import it from there" or "it's taxed regardless, but they'll make it over there for half the price because they just get to pour the byproducts onto the neighbor's land", either way -- add "moving the stuff" to the environmental impact. Maybe while the bill was being written, the Concrete Lobby had "their guy" get some language in there to make sure only a component that makes up a 10% of the final product is what's actually being taxed. The regulators liked it because it's easier to track, the industry liked it because if they just import that part, that'll lower how much has to be moved. There's a loophole somewhere that'll require further adjustments to the regulation/law. In the meantime, R&D budgets are increasingly being spent on working around the tax.
In an ideal world, that "tax money" would go to a magical entity who's sole purpose would be "to create solutions to the problems concrete solves which have less environmental impact." In the US, it would be worse than "vaporized", it would go to organizations which would spend that money adding oversight/administrative burden and creating jobs that will make it a lot harder to solve the problem (once it's solved, what do we do with all of the regulators...?). Even if that organization existed and worked, the cost to transfer the money from "the business" to "that research organization" will see pennies on the dollar make it to "actually solving the problem."
I'm sorry if this sounds combative or hostile -- it's difficult to express a different opinion and avoid "sounding like a bit of a dick." I wouldn't have wasted the time, though, if I wasn't open to hearing where I'm getting it wrong. It's a difficult thing to argue, as well, because I can't say "OK, give me an example of something that was taxed which accelerated advancement/adoption of a preferred technology that worked better than just letting the preferred technology stand on its own" because once you tax it, you lose the ability to measure the result untaxed. I think the EV tax credit might be a good example of a tax that will turn out to have not been worth the cost. I think once Li-Ion technology reached the point that it was realistic to use in replacement of an ICE, the many, many other benefits beyond "the price of gas" and "smog/pollution." I decided 4 years ago my next car would be an EV, I had no idea what the tax credit was then -- gas/pollution/the tax credit were not factors for me. My factors were convenience of filling up at-home, maintenance, overall simplicity, electronic features, and performance. Any two of those being radically better than ICE and I'm buying electric at a 25% premium. Add to it that my driving patterns have evolved that even the lowest-range EV available in the US would ideally fit my needs, and owning an ICE vehicle stops being a "baseline" and you start seeing all of the inconveniences pile on. Now, in 1999 when GM produced the EV-1 using a $40,000 battery that was in (most ways) worse than an ICE-based vehicle, there wouldn't have been any amount of green points" that would have gotten all but the wealthiest among us to buy one. The tech was so far* from being ready that even were it offered at competitive prices it would have been dismissed.
There's a Romanian startup that tries to address part of the issue. They estimate that their technology can decrease concrete use by 30%: https://svelte.eu/
No doubts about "traditional" wood elements (beams and the like) made from trees, they show quite good fire resistance, basically when on fire an outer shell of carbonized material forms and acts as a insulating layer that keeps the core stable for relatively long times.
But in many "modern" structures the large, structural parts tend to be made of composed materials, essentially smaller parts glued together.
In these cases the weak point becomes the glue used in them that may make the element fail well before a monolithic wood one.
Of course it depends on local codes and standards, but generally speaking these elements need to be protected by either anti-fire paint or gypsum panels.
For those clicking in, seeing the length and thinking something like "Pages and pages; sounds really alarmist" and are ready to click off, he ends up doing a really thorough job also explaining what advances have been made, what's being looked at for each of the various identified problems and it ends up being an interesting and informative piece on the subject ... if you find Concrete interesting. (That's a pretty good tl;dr if you want one, but it makes me sound (at best) underwhelmed or (at worst) grumpy, so ...)
I'm kind of reading this thinking "that sounds like a bunch of crappy things to say" and I can't find a way to accurately explain where my head was at without kind of sounding like "a dick" -- it's really not intended. I get extremely annoyed with alarmist articles, especially those with the words "Carbon Footprint" and "Climate Change" in the title[0]. I am not a "Climate Denier"-whatever-boogie-man, I've just noticed that articles with those words in the title are (a) almost certainly going to tell me nothing I don't already know -- they're very low-information, (b) they're low-information because their audience is the general public usually for the purpose of getting them behind some government action that will "move money around and help nothing" or (c) no-information because the goal was to scare you into clicking.
I feel really badly for getting annoyed at this article given that it was none of these things, but turned out to explain history, current state-of-the-art, the various problems, various approaches being looked at by industry/in use (or near/in research). Failing to include those components causes readers to fall into a "mental trap" that I'm sure has a name, but which I don't know. It's the "5% of cars are electric vehicles, we expect that to grow to 10% but if ((really unpalatable/expensive solution)) isn't done, we won't have the charging/grid/etc capacity to support it!", ignoring the fact that ten years ago we didn't have the infrastructure to support the 5% that we have, today and assuming that we'll suddenly stop building out new infrastructure.
"Humanity"[1] advances at an accelerating pace. It's easy to get lost in that word. A way that helps me grasp it better was told to me in fifth grade: as time goes on, we double the amount of things we know in less and less time. Yes, we lose things, too, and even regress in places, but we're getting better at that, too and overall we're ahead. By including past advances, current state of the art and where things are heading, the author reminded the reader that "the world is moving around all of these problems, too."
It also presents the trade-offs correctly. I find it interesting that -- in my lifetime -- I've watched 12 miles of a 6 or 8-lane cement road get blown away and rebuilt twice (along with years of roving maintenance). Grumbling about "it seems like they work on that same road every other year despite replacing it every 25 or so" aside, the differences in how they are built and the final product are astounding. Gone are the rusting painted iron road bridges, replaced with cement. In two cases, a 2.5-year (and I mean, in-between snowfalls on both ends of the year) job took under a year to do the second time. I think the biggest difference was how the road bed was put down. Before, it was methodical, a few squares at a time at various stages in the "pouring from the cement truck" to "cleaning everything up and smoothing the top out". In all cases the last several years, it's some combination of "prepare the foundation the surface of the road will sit" then over two weekends this machine the width of the entire road rolls down the bed while about the same number of workers manage the machine. They finish it off with curbs/the like and Bob's your Uncle. If this similarly reduces the cost (I have to believe it does but I have no data), an interesting equilibrium has to be reached between price, the time it takes to build[2], maintain and destroy[3]. Unfortunately, the raw "price" of the most expensive part and "how long the voters will be furious" will win out provided everything else is "barely passable".
[0] Calm down... just read on.
[1] I know, what's "Humanity" -- a subset of humanity, of course, but enough of us to matter.
[2] And similar balancing of civilian annoyance: I'm OK with an important highway being taken out for a year every 25 or so if maintenance is "knocking a lane out for a few months every 5 years" instead of "knocking most of the highway out for most weekends every other summer" for a material that goes down in a few months (or lasts for 50 years, etc).
[3] Extremely durable/robust concrete is great until it's time to build a bypass through town and some roads need to ripped up before their useful lifetime. Concrete that survives being beaten up by God, semis and all of us for hundreds of years is going to be resistant to ... a lot of stuff.
Are these the same architects who have inflicted a shitscape of low priced high rent cookie cutter 1+5 block projects on us? If so, then why should we care what they think?
I'd long been part of the camp that says "on the whole, concrete's not that great of a material to build with, for a bunch of reasons, but it's also got some significant upsides."
Then, I stumbled backwards into this crazy building technique that solves _some_ problems really well.
It's this traditional building technique called "rammed earth".
It's updated a smidge for modernity, but it's basically the same today as how buildings were built 1000 years ago.
Mega beautiful, practical, interesting constraints and opportunities, anyone can build them, etc.
Wikipedia: https://en.wikipedia.org/wiki/Rammed_earth
Video from a skilled modern-day rammed earth structure builder: https://www.youtube.com/watch?v=jijU-4A8jAk