A Concrete Problem

something within that spirit. And recently I was perusing Scientific American like I do, and I saw an article by Benjamin star Ow titled X Prize Winners use c O two emissions to make concrete and We're gonna get to that, and Starrow made some excellent points. I highly recommend the article. But that article made me think, I should you an episode about concrete. We depend very heavily upon concrete. It is the most frequently used material around the world for

the purposes of, you know, building stuff. It's the literal foundation for many of the structures we build. And the production and transportation of concrete represents a truly enormous source of carbon emissions, which of course are major contributors to climate change. And so I thought I would dedicate an episode to concrete. Now, you could argue it's not high

tech stuff. Most of the time, concrete doesn't have you know, cool circuitry or artificial intelligence or anything like that, although we will talk about the technology that does use some of that stuff. However, concrete represents a technological advance, and there are some interesting technologies, like the ones that use CEO two to help actually make concrete, that we can talk about. But first let's talk about what concrete is.

It is a material that is made up of aggregate, that is particulate material that ranges from medium grade down to course. So think of stuff like sand or gravel, or pebbles or crushed stone. These are loose, small, individual pieces of hard material. Now, obviously you can't just build with aggregate all by itself. You would end up with piles of particulate. You'd have sand dunes or or piles of gravel, which is not terribly useful. So another part

of concrete is a binding agent. This is essentially a glue. It holds the particulate together and we go from having a pile of sand or gravel to concrete once we mix it with this binding agent, which gives that that material strength, and the result is something that's akin to an artificial stone, but it's one that when it's still in its viscous form, you can actually shape the stuff.

Then it will harden and will hold that shape. So rather than having to look for a stone that's just the right shape, or having to employ a stonemason to cut an existing stone down to the correct shape, you could just, in theory, make one yourself out of concrete. Another important aspect of concrete is that it's chemically inert. It is not reactive to stuff, so it's very stable. You don't have to worry about concrete getting wet and

then going all droopy. Though with concrete, water does actually make a difference, but we'll get to that, because water is all part of the system. Now. Depending upon your point of view, you might argue that the binding agent for concrete has to be cement in order of you

to consider the finished product actual concrete, otherwise it's something else. However, other people are a little more loosey goosey with a definitive terms, and they will use concrete to refer to materials that relied on other binding agents to hold together, particulate, or sometimes they might give a little ground, and and they'll call such stuff a sort of a predecessor to concrete.

The discovery of cement probably dates back thousands of years when early people's observed something interesting with regard to their cooking fires. So people would dig a hole and into that hole they would, you know, build their their cooking fires. And those high temperatures from the fires would cause the edges of the hole to kind of dry and crack and sometimes even turn into a bit of a powder.

And when it would rain, water mixing with that powder would sometimes become a sludge that would then harden into

a stone like material. Now, one source I looked at for this episode was a paper titled Concrete History and Stories from World Scientific Now, according to that source, these ancient peoples used a protoconcrete to start construction on the famed hour of Babel, you know, the one that in the Bible was began construction and then God said, hey, guys, I don't dig how you're building up to the heavens, so I'm going to give you all different languages and

scatter you so that you can't taught to each other anymore. But according to this paper, uh, what was happening was that the builders kind of ran out of raw material before they could finish construction, and then they just sort of abandoned the project. Now, several ancient civilizations used different aggregates and binding materials in an effort to create artificial stones. The Assyrians and the Babylonians used clay and bitumen. And you might not be familiar with bitumen um, And in fact,

I don't even know if I'm pronouncing it correctly. I should have looked that up before this episode, but hey, let's wing it anyway. It's a petroleum based type of hydrocarbon, so it's a If you were to break down its chemical composition, you would say it's a compound of hydrogen and carbon, which is pretty common. In fact, that's the reason why a hydrogen based economy is harder than what it sounds like. Hydrogen is almost always bound to something else,

and frequently it's carbon. Anyway, it's extremely viscous and it's really dense stuff, and it can be found in pitch lakes and oil sands out there in nature. So in some parts of the United States, it's referred to as asphalt. Though the asphalt we used to pave roads is made up of other stuff in addition to a binder made from bitamin or a bitumin like substance. Meanwhile, the Egyptians

and the Phoenicians were using gypsum and lime. Gypsum is made of calcium sulfate dihydrate, and it's a big ingredient and lots of stuff including drywall, chalk, fertilizer, and modern cement. Lime the material, not the fruit, so you don't you don't put this in a coconut and drink them both up. In this case, we're talking about an inorganic mineral made of calcium and various oxides. The Greeks also use lime, and they treated it in kilns to create burnt lime.

Like kilns are an important element of creating cement. You couldn't just use this material as it was, you know, found in nature. You had to treat it to heat in order to have the chemical transition into what would become concrete or cement. Rather, we'll talk more about processing lime in a bit, because that does play a huge part in the production of cement. In fact, many early civilizations would use kilns similar to or in some cases exactly the same as the kilns that they would use

to fire pottery. The kilns would reach the temperatures needed to quote unquote burn the lime, making it suitable to use as a binding agent. Most of these early forms of protoconcrete would cure in the air. They hardened upon exposure to the air, or, as spinn Thalo put it in an article in nineteen sixty seven, quote lime that needs air to achieve strength end quote. I like that phrasing.

Then came the Romans. And while the Romans stole a ton of stuff from the Greeks, they also innovated quite a lot of stuff themselves, and one of those things they innovated was concrete. Now, the Greeks had been using concrete a little bit, but not anywhere to the extent that the Romans did. And the Romans discovered natural cements called Pozzolan's. Actually, I should say that Pezzolan's might have already been in use pre Roman times, but the Romans

really went ham on the stuff. Mm hmm, ham and pozzolan. So what the heck is pozolan? Well, according to the American Concrete Institute, it is quote a solicitous and aluminous material that in itself possesses little or no simentitious value, but will in finally divided form, and in the present some moisture chemically react with calcium hydroxide at ordinary temperatures

to form compounds having sementitious properties. End quote. That is a mouthful, but in plain English it means that it's a material that when ground up into a powder and mixed with water and material that contains calcium hydroxide, it becomes cement. Like that is, it can bind aggregate as cement and form concrete. Actually, I should point out in fact I Probace should have done this already. Cement and concrete are not the same thing. They are not synonymous.

Cement is to concrete what flour is to a cake. Right. It's an ingredient, it's an important part, but it is not the same thing anyway. The source for the Romans was a puzzolonic ash, which in itself came from volcanic ash and pumice. So the Romans would collect this ash and they would use it with calcium hydroxide to create their cement. When did they start doing this, well, we're

not really sure. It wouldn't have been any later than one fifty before Common era or B C. As there's evidence of concrete structures dating from around that time period, so it was definitely at least as late as that. It was probably earlier, much earlier. But there's just no Roman record that says, quote, it's to seventy four b C. And we just invented concrete. Also, why are our years counting down backward? Anyway? I'm off to the vomitorium end quote.

And yeah, I made at least two dumb jokes based off inaccurate representations of ancient Rome's timekeeping in terminology, but I couldn't resist. Concrete would play an enormous part in the Roman architectural revolution. In fact, it was such a crucial component of that movement that we sometimes referred to

it as the concrete Revolution. This marked a period in Roman history of huge architectural projects, including the famous Roman Pantheon, on which was has a dome made from concrete that, from its shape, supports itself with no need for additional columns or other supports apart from the walls, which kind of act like columns. The Romans could build enormous structures

thanks to concrete, which could be poured and then cured. Well, it's the quote process of controlling the rate and extent of moisture loss from concrete during cement hydration end quote. That's the helpful definition from cement, Concrete and Aggregates Australia. So let's dive into that a little bit further. Hydration is the mixing of water with cement and aggregate that gets this whole binding process going. And I realized this is skipping over the modern method of producing cement, but

we will get back to that a bit later. Right now, we're talking about Roman concrete, which uses a natural cement with fewer controls, and that meant consistency was a little variable. Okay, So you make the concrete by mixing together water, cement, and the aggregate, which forms a workable paste. You put this where you want it to go, such as in a form mold. So imagine that you've got like a wooden box that doesn't have a top and the sides and bottom are all removable, So you put it together.

Then you pour the paste into that box so it takes on the shape of the box. Then you remove the wood once it's all done. But the once you're done bit is important. So the Roman concrete, like modern concrete, required hydration. That is, the cement needed moisture to harden further. Once dried out, concrete is set, and generally speaking, the

faster it dries out, the weaker it is. Don't get me wrong, it's still strong stuff and it can withstand incredible compressive forces, that is, forces that push down on it, you know, in an attempt to compress it. But it can also be a little brittle, and if the concrete remains wet, the reactions within cement will tenue and sometimes for years if it remains moist before drying out. It's

this process of hardening that is called curing. It's not the drying out part, it's the hardening part that's that's kind of the the end process is dried out. It's the keeping it wet in order to get the hardness and strength you want. That's important. Um and in fact concrete part of that mass is made up of water. Chemically, what's going on is calcium silicates are undergoing an exothermic reaction. As they interact with water, they release hydroxide ions, calcium ions,

and heat. The bit about releasing heat is what makes this an exothermic reaction. Eventually, calcium and hydroxide ions saturate the system and they begin to form calcium hydroxide crystals. Meanwhile, calcium silicate hydrate forms. The crystalline structures provide seed points for further ions to kind of glom onto, and the process can grow from there. But it does need water to continue this reaction, and as those crystals form, the

concrete gets harder and stronger. Controlling this reaction falls to the rate at which water molecules can diffuse through the calcium silicate coating. As the reaction progresses, that coding gets thicker and it gets more difficult for water to make its way through, which in turn means the reaction begins to slow down. Hydration will continue as long as water can get into the system and as long as there

remains unhydrated compounds within the paste. This process can go on for days or weeks, or months or even years. I'll be there for you when the rain starts to fall. As long as water can permeate an access unhydrated cement, the process will continue. Also, while the reactions release heat,

this process itself goes through an interesting revolution. Early on in the hydration process, the reactive mixture will release a good amount of heat, the temperature will will go up several degrees, but after the first now fifteen minutes to half an hour of the reaction, that temperature starts to drop.

Then a few hours in the amount of heat it releases will begin to climb again, and over several hours it will peak, and once you get like twenty hours in, it will then begin to slowly drop the temperature again, very slowly ramping down. And what's happening is that the rate of the reactions themselves changes as things initiate and then water it continues to react with the cement mixture.

Then it gradually becomes more difficult for water to make its way to unhydrated elements of the cement, so the curing process can be done without having to heat anything else up, and in fact it itself heats up. As we'll learn a bit later, that's kind of the opposite of the actual modern process of making cement. So concrete formation is exothermic, but the production of cement turns out to be endo thermic. I'll explain more later on this episode.

Now we've got some more to say about the process of concrete forming, and we'll talk a lot more about cement in just a moment. But first let's take a quick break. Now. I mentioned that if concrete dries out quickly, it won't be as strong as concrete that was hydrated properly. But let's get a bit more detailed with that, because it's not as simple as just you know, drenching wet cement mix as you wait for it to cure. The amount of water you add makes a difference. The ratio

of water to cement is important. A low water to cement ratio means you're gonna end up with concrete that's very strong, but it's also very difficult to work. So, in other words, the paste will be extremely viscous and you might end up with shapes you totally didn't intend and now you're stuck with them unless you, you know, grab some heavy duty tools. High water to cement ratio means you're gonna have a paste that's really workable, but the over all strength of the concrete will be low.

So it's not just how long the cement is kept moist, but how much water you use to do it. In our modern era, there are other things we can add to cement and aggregate to improve stuff like workability, and plasticity and strength. But let's get back to the Romans, because we've got to get back to them, because they're always Roman around. It's a dad joke. The Romans learned about the hydration process and produced a lot of concrete, at least for the time anyway, They relied on the

natural cement features of volcanic ash. Many of those structures exist in whole or in part today, which is really just a testament to the strength and durability of concrete.

But there was a pretty long span of time between the fall of the Roman Empire and the widespread use of concrete and other civilizations outside of some uses in building in churches and cathedrals, And it may be that the knowledge of producing concrete was largely kept in religious scents as far back as the earliest examples of the stuff, which gave the edge to the clerical folks out there

over everybody else. So the Roman Empire trips on a bananappeal and falls and Europe plunges into the Dark Ages kind of. I mean, the history of the Dark Ages is actually really complicated, but for our purposes, the secrets to cement and concrete are largely lost until the fifteenth century when the rediscovery of an old manuscript written by

Marcus vitruvious Polio, usually just called Vitruvius, rekindled interest. Now, Vitruvius was an architect and engineer way back in the first century b c. He wrote a long manuscript about the principles of architecture, and it included a section on the production of Roman concrete. So as the Renaissance began to bloom in Europe, there was a new interest in concrete.

In fact, Giovanni Giocondo used Roman concrete to build a part of the bridge called the Pont the Notre Dame in Paris in fourteen nine, which, as I understand it is widely thought of as the first example of the modern use of concrete, and it was also necessary. The Pont Notre Dame sometimes gets called the most ancient of bridges in Paris, but this is largely a matter of point of view, because it hasn't always been the same bridge.

The Pont Neuf is the oldest bridge that remains in its original form in Paris, but there has been a bridge at the location of Polt Notre Dame. The longest. However, that Pont Notre Dame Bridge has gone through multiple collapses and demolitions and otherwise has been destroyed numerous times, only to have been rebuilt. So this is a real ship of theseus kind of thing we've got going on here anyway.

Giacondo used a recipe of Roman concrete as part of the rebuilding process after the bridge suffered a collapse in fourteen ninety nine when the way of houses on the bridge proved to be too much for the old structure. This version of the bridge, the concrete one, stood largely unaltered until eighteen fifty three, So that was back in four but widespread use really wouldn't kick into high gear

for a few more centuries. In seventeen seventy four, an English engineer by the name John Smeaton learned that by using quicklime as an ingredient for making cement, he could make better, harder cement, and later in seventeen ninety three

he discovered something else which brings us to calcination. Calcination is the process of heating up a solid to a very high temperature, and the purposes to burn off any volatile substances within that solid mass so that you're left with a more pure lump of whatever it was you started off with. Smeaton discovered that calcinating limestone that had clay content in it would produce hydraulic lime. As the

name implies, this produces a lime that hardens underwater. Three years later, an Englishman named James Parker patented a hydraulic cement produced by calcinating limestone that contained clay. Engineers began building lime kilns, essentially ovens dedicated to calcinating limestone. So they were trying to recreate the effect that those ancient peoples saw around their their fires, their food fires, years and years and years centuries earlier. Now let's skip ahead

to eighteen twenty four. A builder named Joseph Asten found that by grinding up chalk and putting it in a kiln with clay produced an even stronger type of cement. This is the type of cement we call Portland cement. It's named after the Isle of Portland in the English Channel. It's where a type of limestone called Portland stone comes from, and that stone played a huge part in British architecture. Fact it still does. More people made contributions towards the

understanding and production of cement. But the next innovation I want to talk about came courtesy of Frederick Ransom. Ransom wanted to find a way to consistently make the best cement, which required a new type of kiln. So the old cement kilns were essentially vertically aligned ovens. So think of like a chimney. You would load this stuff up with limestone and clay, You would have fuel at the bottom.

You get the kiln up to a certain temperature, and you would kind of mix everything together, and in between loads you might even allow the oven to go cool, which represented a pretty darn big waste of energy because it takes a lot of fuel to get kilns up to temperature, and once you get it up there, it takes less fuel for you to just keep it there than it would if you let it go cold and

had to start it up again. And by high to pachures, we're talking up around four dred degrees celsius and hotter. The result of this process is that the limestone and the clay partially melt together into nodules that are called clinker. The clinker, once cooled, can be crushed into a powder mixed with gypsum, and then you've got your cement. A lot of stuff actually happens in this process, but I'm going to explain more in just a moment, so stick

with me. Ransom figured out that one way you can make a better kiln is to go from this vertically aligned, you know, smokestack style kiln to a tilted one, one that was almost closer to horizontal than vertical, but still on an incline. So the raised end, the part that's higher up, would be where you would feed limestone and

clay into the kiln. On the opposite end, the lower end, you would have an opening at the base where clinker could pass through, and that's also where you would have your heat source that would get the raw materials up to the right melting point, and the whole thing would rotate, shifting material around and causing it to gradually move down

the length of the kiln. It was a rotating kiln, so you would feed in your mix of limestone and clay at the top and at that end of the kiln, far from the heat source, you would have the relatively chilly temperatures of between seventy two degrees celsius. At this temperature, any water content in the feed would evaporate off. This is also the end where any gas is given off by the process would escape. The raw material would then sift down further into the kiln as the kiln rotated,

and it would start to reach hotter segments. So once the material reached between four hundred to six hundred degrees celsius, the clay would start to decompose into oxides like silicon dioxide and aluminum oxide, and the limestone would decompose into

calcium carbonate, magnesium oxide, and some carbon dioxide. So some of that carbon dioxide would then expel out the end of the kiln, but we would continue our journey down the kiln, and now the raw materials are reaching around six hundred and nine hundred celsius somewhere in that range, and the calcium carbonate from the limestone would react with the silicon dioxide to form a material called the light or B E L I T E, also known as

die calcium silicate. So this again continues to sift down the length of this rotating kiln, and of course it gets even hotter as it gets closer to the source of heat, and around nine hundred two thousand, fifty degrees celsius. Any remaining calcium carbonate decomposes into calcium oxide and more carbon dioxide, which again exhausts out the end of the kiln.

Then the material gets towards the point where the hottest section is with temperature is getting up to around four hundred fifty degrees celsius, and the raw material begins to melt and fuse into clinker, which sifts down through and opening at the base of the kiln and falls into a cooling tank. Modern rotating kilns recapture the heat from the clinker and they use that as part of the way to power the system. So if you follow that process,

you realize a few really big things. First, the chemical process to create Portland's cement is an endothermic reaction, meaning you actually have to add heat to make this reaction happen. And we contrast to that to the two concrete curing that's an exothermic reaction. It gives off heat. You also probably heard there are a couple of steps there that involve a release of carbon dot oxide in this chemical process. That's one of the big byproducts of cement production carbon dioxide.

But it doesn't stop there. We also have to consider the whole system, not just what gets produced through this chemical reaction. So to power the kilns, I mean to make the heat, we need fuel and that tends to be fossil fuels, and burning fossil fuels also produces carbon

dioxide emissions. So cement production contributes a significant amount of CEO two emissions, both in the chemical process itself of cement becoming cement and also the fossil fuels that you need to burn in order to create the heat to get this reaction going. In fact, global cement production accounts for about five percent of all CEO two emissions, which

is a staggering amount for one specific process. And when you factor into the equation other considerations, like the fact you still have to transport the cement to wherever it's going to be used, you start to see how our dependence upon cement and concrete becomes challenging. Now, let's get some stuff straight. Concrete is incredibly useful and and important.

I mean, without concrete, there'd be no way to build stable structures beyond a few stories, which would mean that we would have to sprawl out even more than we already do. And I should also add that the fact we can build really tall structures like skyscrapers isn't just due to concrete. You see, concrete does have incredible compressive strength, that is, it can hold a ton of weight literally can hold a ton of weight, tons and tons of weight,

but doesn't have great tensile strength. If you build a very tall structure and you only use concrete, you're asking for trouble because something like really high winds or an earthquake could cause monumental damage and even total collapse. But fortunately we have a lot of people to thank for creating more resilient ways to use concrete. One of those people was a nineteenth century gardener in France named Joseph Monnier.

He wanted to create a more durable flower pot. Then he began to experiment with concrete set around an iron mesh frame. He created iron reinforced concrete or ferro concrete. A lot of other people would build literally upon that idea, giving us stuff like the lovely rebar that gives more tensile strength to concrete. So concrete is really handy stuff. It's one of the big innovations that has supported urbanization and industrialization. So it is not easy to say we

should give up on concrete due to carbon emissions. However, at the same time, humans are producing a lot of cement. In twenty the estimated global production was around four point one billion tons of the stuff, and every ton of cement creates nine ms of c O two emissions, which is around one four pounds of carbon dioxide per ton of cement. So that would mean in cement production dumped around three point seven trillion ms or eight trillion pounds

of c O two into the atmosphere. And again that's just figuring in the production of cement, not the transportation or anything like that. And keep in mind might have actually seen more cement production than we did had there not been a pandemic. The four point one billion tons figure has remained fairly consistent since around but back in the industry actually produced an estimated four point two billion tons, so we're not likely to see this number go down

anytime soon. And there are other parts of concrete production that contribute to CEO two emissions, it's just that the manufacturing of cement represents by far the largest contributor. All Right, So we know that making concrete creates a lot of carbon dioxide. We also know concrete is really important stuff, and that it's not as easy as just walking away from the material. When we come back, i'll talk about those researchers who pumped c O two into concrete mix

and what that all actually means. But first let's take a quick break. In two Matt made, the then governor of the U. S State of Wyoming, issued a challenge. It was a competition to find ways to convert carbon dioxide emissions into sellable products. So, in other words, ways to take something that is generally a negative, that is the release of carbon dioxide, and to turn it into a positive. Now, presumably the goal wasn't just to create a product, but to lock c O two into some

other substance so that it wouldn't be part of the atmosphere. Now. Me did this for a few different reasons. One big one is that Wyoming has a coal industry. But obviously coal is a fossil fuel, and burning coal releases c O two, So the optics are not great for the coal industry, and it's hard to get around this fact that this particular industry contributes to climate change, and that in turn poses a pretty big threat to our way of life, which is perhaps the most understated way I

could have put that. So finding a way to capture c O two and convert it into something else and to make it a profitable endeavor would be a great solution. One of the reasons carbon capture initiatives aren't exactly proliferating all over the place is that they tend to be expensive, and often the output isn't something you can monetize. So it's not that we don't know how to capture carbon dioxide. We've got lots of ways to do it. It's just that we don't have a lot of ways to do

it that in turn generate revenue. They represent a cost. So if you're literally pumping CEO two underground so that it's essentially captured down beneath the ground, and you know you're not making any money off that CEO two it's just pumped down there, it's actually gonna cost you money to move the CEO two down there. And businesses, by and large, from what I understand, exists to make revenue.

So generally speaking, businesses don't tend to follow pathways that two expenses if they can avoid it, and carbon capture is expensive. But if you can create a product, Well, then you can recapture those costs, and if the product is good enough, as in popular enough and desirable enough, you can actually make a profit off of it. And now with a profitable plan for carbon capture, you can

kick things into a different gear. Now, what is environmentally beneficial is also economically beneficial, at least in the short term. And let me do a quick aside here. I want to stress wholeheartedly that climate change mitigation is in fact economically beneficial. It's just on a much longer timetable than

most businesses focus on. Businesses tend to look at fiscal quarters or maybe a fiscal year, and mitigating climate change on that kind of time scale doesn't seem to make economic sense because of the expenses involved, and you're not likely to see any kind of you know, results immediately.

But when you pull back and you take a much longer term view, you see the climate change stands as a threat to entire regions and industries, and you realize that climate change mitigation is the best economic strategy in the long term. It's just really hard to get stakeholders to look that far out, as we tend to be pretty short sighted when it comes to stuff like money and lots of other things too. All right, let's get

back to this X Prize competition thing. Out of the competition emerged a couple of teams with proposals for a green concrete strategy, and both teams had shown that by injecting carbon dioxide into the concrete production process, they can both reduce the amount of CEO two that was released

and they can make concrete stronger. One team, called Carbon Cure Technologies injected c O two into concrete wastewater, which didn't turn it into some sort of carbonated beverage, but rather created a mineral that, when added back into the concrete mixture, made it stronger. The second team, you see l a carbon Built, injected c O two into concrete as it goes through the curing process. This approach reduced the amount of carbon dioxide emissions from producing that concrete.

By now, that's just the production of that concrete, not the cement that was used to make that concrete. Keeping in mind that cement production is the real issue here. The reduction in greenhouse gas from concrete production might seem like a band aid on top of a very serious cut. It's not nearly good enough. It's a reduction that is good, but it's not eliminating the vast amounts of c O two given off through cement production. The process does require

CEO two. That means that you could create carbon capture systems and pair them with facilities like a cement production facility, so the CEO two generated from cement production would go toward making better concrete. But honestly, these facilities produce way more carbon dioxide than you would need to produce green concrete solutions. You would really need to build in capture

and sequestration facilities into cement production plants. But like I said earlier, those solutions are expensive and they represent an economic cost to the companies. It's possible for governments to create incentives to reward companies for capturing and sequestering carbon, but outside of that it's a tough sell, and even the political approach is super difficult because there are a lot of politicians who aren't exactly swayed by the science

of climate change. Meanwhile, there are engineers looking to find ways to reduce the amount of carbon emissions released during cement production, largely by fiddling with the formula. A big source of the problem is that the materials in the process of make cement have to be heated up to around fifty degrees celsius or hotter to form clinker. Finding alternatives to those materials that can react at lower temperatures would release the amount of fossil fuels that you needed

for the process. Another solution is to look at byproducts generated from other industries like fly ash and use those as additives to reduce the amount of cement production that you need in order to make concrete. So, in other words, if you are using fly ash to make up some of the weight of the cement, you don't need as much cement to make concrete, and as long as the finished product is as good or better than existing concrete,

your golden Now. I also didn't really cover this, but with the hydraulic nature of concrete the need for hydration, there's also a big need for water. In fact, the concrete industry takes up nearly ten of industrial water use and nearly one point seven percent of total global water use. So not only is it dumping CEO two in the atmosphere, it's using up a significant amount of water and in some areas of the world that might not be a

huge deal. But for other areas that are affected by water shortages and droughts and have a need to lay a lot of concrete to build up their their infrastructure, that's a huge problem. Water resources are precious, I mean, wars are fought over them, and an industry as thirsty as concrete production adds more pressure. One thing I wanted to close on was a cool technology that uses cement products similar to concrete as an ink in a three

D printing application. These companies are using enormous three D printers to print buildings, and there are actually a few different companies doing this. One of them is called icon Icon has a large industrial three D printer called the Vulcan two, which uses a cement based building material which the company calls lava crete as the ink. So with the Vulcan Too, it's possible to print out a single

story building. The Vulcan too can print walls that stand at a maximum of eight and a half feet tall, and the printer is thirty three ft wide and can print on a foundation that's up to twenty eight feet wide. However, the Vulcan can also move down the length of a structure as it builds it and there's no real maximum length that you would have, like you could in theory build it as long as you wanted it to be.

It would always be at max. Twenty eight feet wide, but it could be as long as you needed, assuming you had the materials and the land, like the level space to build upon. The printer pushes out the mixture at a rate of around five to seven inches of wall length per second, which yeah, that's really fast. So by laying down lines of this lava creet each line is about an inch tall, then you can lay out the outline of your wall structure, and then you start

putting on the second layer. Each layer binds with one underneath it, and so then the volcantuo can print a building, or at least the walls, you know, the internal and external walls of a building. You would still have to provide the finishing touches, you know, stuff like doors and and a roof and ceiling and that kind of thing. But this mixture has the special binding agents in it

so that they do hold together. And using that approach, it's possible to build a house out of a concrete like material within a day or two, depending on the size of the building. The rapid approach to building durable homes could be a huge game changer and help communities address problems like homelessness or creating housing in the wake

of a natural disaster. It's the plasticity of the liquid form of the material that makes it really possible to go through a three D printer device, and the curing process makes it a practical structural material. And I have to emit these are really interesting technologies that could serve as a huge benefit if put to the right use.

That's a big if. However, it requires people to spearhead projects that aim for these goals, and of course that does not change the fact that cement production is still an environmentally costly process. We shouldn't forget that while cement production is a big contributor to greenhouse gas emissions, it is also not the largest contributor. Transportation tends to be

the biggest one, followed by electricity production. And so while it's important that we address issues with carbon emissions from cement and concrete production, we can't focus solely on that issue. If we quote unquote solved it, we would still have a lot of work to do. So if we just look at one thing, that ends up creating a false sense of achievement whenever we make any sort of progress, and meanwhile, we continue to dump tons of CEO two

into the atmosphere. The quest to create green concrete and cement has to be part of our approach to climate change mitigation, but it can't be the only part of it. Well, that wraps up this episode of text Stuff and our look at concrete. There's obviously a lot more we could say. I didn't really go into the various additives that have been developed over the years to change the the the qualities of concrete, but that would require a much deeper

dive into chemistry. And y'all know, when I started getting lots of letters and numbers together, my eyes begin to glaze over. So we're gonna leave it here for now. But if you have suggestions for future topics of tech stuff, reach out to me. The best way is over on Twitter. The handle for the show is text Stuff HSW and I'll talk to you again really suit. Text Stuff is an I Heart Radio production. For more podcasts from my Heart Radio, this at the i Heart Radio app, Apple Podcasts,

or wherever you listen to your favorite shows. H