What’s the most underrated material in the modern world?
How about concrete? Often dismissed as boring, ugly & inert. Concrete is actually surprising, dynamic & incredibly complex.
With that in mind here are a few reasons why we need to start talking about concrete
First off, we use a lot of it. A hell of a lot of it.
Every minute of every day, construction firms around the world pour out the equivalent of more than 200,000 bathtubs of concrete.
Every year we pour enough concrete to cover the entire landmass of England.
The vast majority of concrete these days is being poured in China, to build bridges, skyscrapers, high speed rail etc.
Indeed China produced more cement in the past three years alone (2018-2020) than the US did in EVERY year since the first Portland cement plant opened in 1865.
Or another way of looking at it. Here is the total amount of cement produced in the US over the past decade vs the amount of cement produced in China in the same period. You get the idea.
At this stage you’re prob wondering about why I’m saying both “cement” and “concrete”. Actually they’re slightly different things. Cement is the magic ingredient inside concrete. Concrete is basically sand plus gravel plus cement. Add water and you get an extraordinary reaction.
Calling it extraordinary isn’t overdoing it. The cement reacts with the water to create a kind of gel which quickly and then slowly begins to cure into stone. Look under a microscope and you see lots of tiny stony tendrils forming which bond to each other and the sand/stone.
Scientists still don’t 100 percent understand what’s going on inside cement when it’s setting. In chemistry labs this remains hotly-debated territory. Also intriguingly, it keeps on curing long after it’s apparently set. The Hoover dam is still curing nearly a century after being built!
But the upshot of the chemical reaction is to create a kind of stone you can pour into a mould. Hard these days to imagine how revolutionary this was back in the 19th century when the main alternative was bricks/masonry which was v labour intensive and considerably less strong.
Concrete is very, very strong, especially when you combine it with steel reinforcement bars (rebar) which also give it tensile strength (so you can build bridges with it). The 20th and 21st century world is literally built on concrete, mostly reinforced concrete.
Now, we are not the first civilisation to be v reliant on concrete. The Romans had their own form of concrete (known as Opus signinum) & there’s evidence our ancestors used a form of cement as long as 10k yrs ago. The Colosseum is partly built out of concrete, behind the brickwork and in the foundations.
That brings us to the most amazing building in Rome: the Pantheon. An enormous, pristine, beautiful and quite delicate-looking dome, all built out of concrete TWO THOUSAND YEARS AGO.
It’s still the world’s biggest unreinforced concrete dome even today.
But while modern concrete is stronger than Roman it tends to last less long. This is usually down to corrosion of the steel bars inside. A big problem these days esp in highway maintenance. Many bridges get this problem. Eg lots of these (not Hammersmith) thetimes.co.uk/article/half-…
Anyway, after the fall of the Roman Empire, the recipe for concrete was forgotten. Only in the 15th century, when an old manuscript by Vitruvius resurfaced with hints about the recipe, was interest in this building craft re-ignited. It sparked a race to “re-invent” concrete anew.
When historians write abt the enlightenment, industrial revolution etc, they often talk about steel and science and electricity and so on. They tend to overlook concrete & cement. But in the 18th and 19th century many of the world’s greatest minds were focused on this challenge.
There were countless contenders making artificial stone but the eventual winner of this race was someone called Joseph Aspdin, who patented Portland cement in 1824 (the “Portland” bit was essentially a branding exercise, since Portland stone from Dorset was v fashionable).
No-one is quite sure, by the way, whether Aspdin came up with the recipe himself or nicked it from someone else. If you’re interested in this topic and, well, concrete more generally, Concrete Planet by Robert Courland is well worth a read amazon.co.uk/Concrete-Planet…
Anyway, Portland cement wasn’t quite the same as the Roman variety, whose secret ingredient was a kind of volcanic ash called Pozzolana. In most ways it’s actually stronger. Tho in terms of water resistance we are still learning much from the Roman variety eurekalert.org/news-releases…
To simplify enormously, Portland cement is a powder formed when you roast limestone/chalk with clay, sand and, occasionally, other additives such as iron oxide. You end up with black, unpromising-looking nodules, which are called clinker. Crush them and you have a basic cement.
This all happens in a kiln. Back in the day these were “bottle kilns”: like those old pottery kilns you see in Stoke-on-Trent and elsewhere. But these days they are rotary kilns, vast, hot, titled tubular ovens through which the ingredients tumble as the chemical reaction occurs.
I went to the cement plant in Rugby the other day. It was unexpectedly thrilling. The kiln is the enormous tube here (not the tall tower where the chimney is, which is kind of pre-heating the ingredients).
The kiln here is the biggest in the UK. This plant is actually the oldest still operating in the UK – possibly the world. This plant was making cement for the Victorian industrial revolution. Cement during WWI and WWII. Cement today for HS2 and more.
The kiln has to keep turning, 24hrs a day, partly because of all the demand for cement (LOTS post Covid) but more importantly because if it stopped the heat inside would melt the tube and it would sag & fail. This would be v bad, the plant manager said, with some understatement
Cement plants don’t get much attention. Manufacturing stories fixate on car plants/steelworks but cement is a crucial part of the economy, because of how many sectors it underpins (construction, property, transport). & unlike most sectors we’re nearly self-sufficient in cement.
But there’s growing focus on kilns these days, because cement happens to be one of the trickiest obstacles in getting carbon emissions down to net zero by 2050. Cement is responsible for roughly 7 percent of global emissions. More than aviation & deforestation combined. It’s a BIG deal.
Actually that 7 percent comprises two parts: the chemical reaction as calcium carbonate (chalk/limestone) is heated and the carbon bonds with oxygen, creating calcium oxide (quicklime, key component of cement) & co2. Then the emissions from the kiln’s heat source, traditionally coal.
Its relatively straightforward to remove coal from the equation. The Rugby plant (run by Cemex these days) uses Climafuel – essentially processed waste – to heat its kilns. Here’s the big hangar where they store it. The grabber picks up the fuel and sends it to the heating tower.
This plant – and the UK cement industry – is FAR greener these days. In this country cement CO2 emissions are down 53 percent since 1990 – partly by reducing energy emissions, partly by adding things to the final mix. But the CO2 from that chemical reaction is a far tougher nut to crac.
You can’t achieve the chemical reaction in the kiln w/o carbon emissions. So for the cement industry the only foreseeable way to get to zero emissions is via carbon capture & storage. And CCS is v expensive and while the tech works in theory we’ve yet to see it applied at scale.
Raising another q: can we make cement without emitting co2? Yes and no. One alternative is alkali-activated cements where you add an alkali solution to blast furnace slag or coal fly or waste incinerator ash or metakaolin. You get a really strong cement w/o direct co2 emissions.
Few weeks ago @BrantWalkley and his team at @sheffielduni mixed us up some samples. On the left is traditional Portland cement. Middle is alkali-activated, reducing emissions by c.80 percent. On the right is one that is zero carbon!*
- Whether it’s really zero carbon depends on how you do the accounting. Because it was made with blast furnace slag, some carbon WAS produced by the steel mill from which it came, if not in the cement reaction. Account for this carbon and it’s not zero emissions
This alkali-activated cement is also more resilient to rebar corrosion. Why? It has a higher pH than traditional Portland cement, which helps protect steel from rust. These alkali activated cement blocks have been sprayed with a solution which goes pink when there’s a high pH.
Remaining question: how well these cements stand up to real world use/abuse over decades. We have 200yrs of Portland cement but much less with these ones. Tho there are one or two structures around world made with alkali-activated cement, esp, surprisingly, in the ex-Soviet Union
Faced with shortages of Portland cement in the Soviet era, some chemists/builders experimented with these unconventional cements. Here’s an apartment in Mariupol, Ukraine. Tho few of its residents realise, this building is a site of deep interest to scientists these days.
But while these kinds of cements are much greener the problem is they’re quite hard to scale up. And the defining feature of concrete is scale (back to those first few tweets). And ease of use. One of the most amazing things about concrete is that pretty much anyone can make it.
If we’re going to continue relying on cement (hard to imagine 21st century civilisation without it) and hit net zero we need some BIG technological leaps – soon. Lots of 💰 going into batteries/hydrogen/solar etc. But this issue, unsexy as it might be, is also v v important.
If you’re still, god forbid, interested in cement and concrete after all that, here’s a short @skynews film I made with @maddylratcliffe about it
See more here: pingthread.com
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Howdy
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“Climafuel – essentially processed waste”
From: https://www.cemex.co.uk/alternativefuels.aspx#section0
Climafuel ® looks like shredded paper and consists of paper, cardboard, wood, carpet, textiles and plastics.
ClimaFuel significantly reduces waste sent to landfill, whilst preserving fossil fuel resources.
My capitals.
Several cement plants in the UK are already BURNING TYRES successfully and have demonstrated that the overall environmental impact of using tyres in the fuel mix is reduced when compared with burning coal alone.
They’re burning old oil and paint thinners too, yet: “does not affect emissions or air quality”.
“But while these kinds of cements are much greener
It may be “cleaner than coal, but it aint clean.”
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Howdy
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What is “Tire Derived Fuel” and why is it dangerous?
“What they fail to mention in their promotional materials is that tire incineration under any circumstance creates pollution that makes the air dangerous to breathe.”
https://www.energyjustice.net/tires
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DeadHeartDiary
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The only thing people have to recognize is abundance, suitability, somewhat ironic independent codependence, variety and REJECT homogenization.
You can use almost anything for energy generation, but you have hegemonic, monopolist, artificial scarcity, standardized stagnation sort of appeals.
Like, if you used some calcium, sodium, silica, maybe potassium, magnesium….instead of fucking cobalt and lithium, perhaps you’d get somewhere.
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Carbon Bigfoot
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Howdy:
The title of the website gives you the agenda indication—“Energy Justice” and it is biased from the get go and does not provide fair representation of the facts. Having been involved in waste incineration since the 60s, as BSChE , Professional Engineer I would suggest that with parameters established in the article provides one unique way of dealing with used tires; the other being added to asphaltic concrete for road construction/repaving here in the USA.
None of the chemicas listed can escape combustion annihilation and a coal fired heater the residence time ( something they conveniently didn’t considered ) almost assures conversion to H2O and CO2. Metals in the flue gas are collected into tertiary bag houses. And the rub of the above article CO2 is not a pollutant— and it ruins and extremely great article about one of my favorite building materials….CONCRETE. You can’t make an omelet without breaking some eggs.
Those of you that think industry, or modern life can exist without pollution are naïve as hell. Nature provides far more toxic pollution ( ex, terpenes in pine tree stands, volcano discharges ) more than Humanity—THATS THE FACT JACK!!!
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Howdy
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“does not provide fair representation of the facts.”
Yes, I know C BF. I’m not thick. That’s why I went to the cement site to balance It a bit.
In the same vein, I mentioned the volcanoes because it’s a taboo subject as far as emissions goes.
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Howdy
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After sufficient research, i came to realize my comment regarding the effects of burning tyres in a very high temperature environment such as a cement processing plant was ill-informed and misleading. Carbon Bigfoot was correct, I was wrong. I apologise. I should follow my own advice.
Thank you for the education, Carbon BF
Were you to burn tyres in a fire without the very high temperatures and filtering used, then the result of that is extremely toxic.
DeadHeartDiary
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Hey, you should check out terpenes, like 1,8-cineole. Maybe then you ca n get out of the atmosphere, with minimal pollution.
Sorry, I gotta troll some. With facts.
Howdy
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“In the same vein, I mentioned the volcanoes because it’s a taboo subject as far as emissions goes.”
i actually commented on volcanoes in another article which I confused with this one:
Then there’s the effect of volcanoes. We don’t hear enough about volcanoes.
Just attempting to clear up confusion and because It is pertinent to the events.
Howdy
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“Hey, you should check out terpenes, like 1,8-cineole.
Sorry, I gotta troll some. With facts.”
Since you stated none, let me know when the facts are here to see.
Jerry Krause
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Hi Carbon and other PSI Readers,
GREAT COMMENT!!! Readers, please attention to those who have actual experience about that which they write.
Have a good day, Jerry
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DeadHeartDiary
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https://phys.org/news/2019-08-key-phosphorus-based-molecule-life-earth.html
https://www.airspacemag.com/daily-planet/phosphate-problem-origin-life-may-be-solved-180973899/
https://www.airspacemag.com/daily-planet/phosporus-you-cant-have-life-without-it-least-earth-180967243/
ATP isn’t central to what’s known as life, is it?
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DeadHeartDiary
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I mean, they kinda do call it the devil’s element and you know what else the say about the devil and life on earth.
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DeadHeartDiary
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I did mention the starcraft and shit, right?
Yeah…
https://www.lmsal.com/solarsoft/latest_events/
https://bolzer.bandcamp.com/track/phosphor
I got MUCH MORE, where that comes from.
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James
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Concrete was a quick fix used after WW2 to build millions of bridges and suchlike as needed for the new road systems. For me the most underrated material is steel. It’s what keeps the concrete up in the air, even for 50 odd years and even in salty sea air. However after that, it can corrode and let the concrete down, literally, as in Morandi’s Polcevera Bridge in Genoa. We can solve the problem by demolition and rebuild; with steel alone, as we have seen.
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