Zero Emissions Cement is Closer Than You Think
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- เผยแพร่เมื่อ 18 พ.ค. 2024
- Concrete is the second-most-used substance in the world after water, and it's responsible for 8% of global CO2 emissions.
But, what makes concrete so indispensable and strong? The secret ingredient is cement. Cement is what binds everything together and gives concrete its strength - and also where most of the emissions come from. In 202, more than two and a half billion tons of CO2 were released from cement production. While cement in concrete can be recycled, the demand far outstrips the amount recycled each year, which means we have to produce a lot of fresh cement.
There are things we can do to limit how much we use, but because developing countries are using increasing amounts of cement to build housing and infrastructure to improve living standards of their booming populations we’re going to need more and more each year for a while yet. That means we need to find a way of producing it without the emissions, and unfortunately cement-making is likely to be one of the most difficult sectors to decarbonize.
But though it’s difficult, it’s by no means impossible. In this video we’re going to take a look at how traditional cement production works, where the CO2 comes from in that process, why it’s so hard to get rid of, and how we can make cement without CO2 emissions. I’m going to try and make the abstract concepts a bit more… concrete.
Bookmarks:
00:00 Intro
01:29 Laying the foundations - Cement vs Concrete
02:35 How is cement produced?
03:55 Methods of reducing emissions in cement production
06:48 Can we avoid using lime altogether?
07:56 Carbon Capture and Storage using Cement
09:40 Removing emissions from heat
10:33 Outro
Sources:
(coming soon)
The Engineering with Rosie team is:
Rosemary Barnes: presenter, producer, writer
Kevin Irman: research, calculations, assistant editor
Javi Diez: editor www.linkedin.com/in/javierdie...
David Hodgson: writing and research
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IIRC the --Brisbane International Airport-- runway (HUGE amount of concrete) used a carbon negative geopolymer, developed by a local university.
Edit: oh it wasn't Brisbane's Airport, it was a Toowoomba airport (a town 130km inland of Brisbane.
*"BWWA is built with approximately 40,000 m3 of geopolymer concrete making it the largest application of this new class of concrete in the world" [2015]* Nice
It's not the only one. Calgary also has a geopolymer airport.
70% cheaper than OPC.
I didn't know that! If I ever fly into Toowoomba (or Calgary) I will look down and remember to be impressed 😊😊
There's been one in South Africa for a decade, too.
th-cam.com/video/wArEbfC91m0/w-d-xo.html
Many thanks for such a concise summary of the state of low-emission concrete.
Keep up the great work!
That was very well researched. Thank you Rosie.
I was not aware that China is on better 57% while it seems the rest of the world is on 65%. Is this because of regulations or why can't we improve like China?
Having been in Peru and walked up to the Machu Picchu but missed Puma Punku, personally I am looking to Polymer Concrete since I got to know that even the Pyramids in Egypt nearly for sure were made in this way. Trying to get more knowledge and experience but also interested in the different results and expenses between the solutions.
That was a lot of information in less than 11 minutes. So much so that I'll forgive your pun to close your intro. 😎 Having had 4 decades of time in and around the building industry I think the initial low hanging fruit is use reduction. As you pointed out there are areas that could benefit from thoughtful engineering to reduce concrete use, and there are opportunities to eliminate concrete in some areas as well. Concrete free "slabs" for on or below grade construction are viable and within the ability and skill set of almost all builders. They merely need to rethink a few steps in the process.
An excellent summary of the progress towards net zero cement and cement alternatives. Thanks, Rosie et al.
Thanks so much!
Cradled by concrete
Is my band name
Love your videos Rosie. I can see lots of improvement in them since you first started as well. You speak more naturally and the transitions between points are much more confident and fluid. I don't know if you're editing them yourself, but there's also definitely a higher quality of editing since you started. It's really nice to see you growing into something you've obviously put so much effort into.
Your videos are fantastic, and very informative, thank you.
I believe she is employing an editor now, yes.
Thanks for this very nice comment! I found a great editor, Javi, about a year ago. He's got an engineering degree so he is a perfit fit for the channel. I'll pass on your compliment to Javi!
I think that you have forgotten to mention that cement absorbs lots of CO2 while hardening....
Yes I should have 😊
Great stuff! I always learn something from your videos.
Sublime has the best name. Until someone gets a viable, scaled manufactory, I'll stick with the best name ^.^
I agree one million percent.
Loved the video Rosie, learned so much about the cement making process.
An excellent review. One point that seems to have been missed: much of the CO2 driven off in lime production (calcination) is re-absorbed by the cement, just over the ~ 100 yr timeframe, so not fast enough., but carbon neutral over the long term- so the real issue is the energy, not really the calcining..Alternative cementitious materials, wiser use of cement, alternatives TO concrete for above-grade construction, electric heating in calcination, biofuels for clinkering, and CCS...they're all needed. Note one thing missing here: hydrogen. I don't think there's really a role for hydrogen in cement production because the clinkering kilns need a radiant flame- they don't even like burning gas, they'd prefer coal. Hydrogen is definitely capable of generating the required heat (at tremendous cost) but isn't a perfect fit. Biogas methane with the addition of biochar is a better fit there.
Thanks for adding those extra points. Does cement really reabsorb ALL of the CO2 from lime production eventually? Even in the middle of a thick slab?
Seems like an imperfect CO2 sink.. wonder if the 100yr timeline has an effect? And seems logical that only x% of the volume would capture CO2 (exposed).
AND we would have to make sure all buildings remain in use over 100 years…. With all inefficiencies we might end up wirh 15-20% of the original CO2 captured … changing materials sounds better
Great and thorough video. Glad to see that CCS is actually being used in the industry already.
outstanding video. well explained, infromative and clear. 👍
Thank you Rosie for all the excellent information on your channel. Just one comment, on one of your videos you were somewhat puzzled by the use of ebikes. I live in a very hilly part of the world and which meant any trip on a normal bike is a sweaty task. I wanted a mode of transport that allowed me to pop around town without breaking a sweat and that was an ebike. Best purchase I have ever made, it allows me to get out and about, run errands, small shopping trips etc, without going near my car and without needing a shower everytime I take it out. Ans as a bonus I also discovered that I am getting fitter despite it being an ebike and overtime reducing the level of assist I need from my ebike. It has become our second car greatly reducing any short trips we would have taken (5km ) and even some of the longer ones (40k). I would highly recommend them to anyone wanting to reduce the time they spend in their cars, but are not fit enough or have challenging geographic location for a normal bike.
Really informative summary of the production process, emissions sources and potential mitigation solutions. Would be great to see more 'overview' videos like this for other hard-to-abate sectors like shipping, chemicals, aluminium, heavy-duty vehicles etc 🙂
Crude oil is compost.
Compost that's been compressed, heated & stored for millions of years, none of which are necessary to use it as feedstock for oil refineries. I don't know if 80 million barrels per day of compost is available though, especially as the raw vegetable matter is stored for a few weeks while it turns into compost (though that stage may be unnecessary too).
@@alanhat5252 this is a common misconception. Very little of oil is composed of what we would typically call compost such as leaves, tree trunks etc. The majority is actually decayed algae and zooplankton or phytoplankton (minuscule animals and plants) from a very large time window roughly 250-65 million years ago. You are correct that modern technologies permit us to create different types of fuels nearly directly from various sources including plants like corn for ethanol, but engines would have to be redesigned to run 100% ethanol. Porsche has an interesting but very expensive method which uses electrolysis to split water and eventually refactor that into race fuel quality methane using atmospheric CO2.
Other companies are using bioreactors to induce production of methane or similar from algae, but all of these methods don’t scale very well and would not be sufficient to power all the vehicles in use today.
Keep your eyes peeled for aluminium! Should be ready to release next week. Shipping and chemicals are on the list, and for heavy vehicles the closest I did was this livestream with David Cebon on trucking th-cam.com/users/livefkbcZ-UzOso
Many thanks for your comprehensive analysis, which certainly does include as a major factor avoidiing concrete use, which some commentators seem to not have taken on board!
But there is no way it will reduce to zero, so you also cover techniques for reduction, some of which I was previously unaware of.
Kudos.
Thanks for the great video. Love your channel, I watch it regularly. Mass timber can replace concrete in so many. applications from buildings to bridges. It is great to get to zero emissions concrete but that doesn't solve the problem that it is a finite resource. Keep up the great videos!!
Thank you for this comprehensive yet succinct review.
Excellent video, condensing loads of info in a structured way in just a few minutes. Hats off!
Loving the set. And cool to see the progress made in production. And as always informative and good content
the video you include about MCi international isn't linked, just to let you know! great content as usual, well done
Oops! Thanks for letting me know. I'll go add it now 😊(nice to know someone is clicking those cards!)
These video's are really well made. Easy to follow and not pandering to whatever crowd it's trying to reach. We really need this for a responsible transition. Well done, Girl!
This is top-quality journalism, we need these principles to spread around the world, voters cannot make informed choices without it.
the video quality and production really went up. congrats!
Albert Bates, co-author of "Burn: Using Fire to Cool the Earth", is developing a process to add up to 20% of biochar to bitumen for road surfaces. Biochar, as the book describes, also has a role for improving concrete. This meshes with Rosie's first solutions point to "use less of it" and require performance standards instead of requiring a set amount of cement.
I talked about biochar a little bit in my CCUS video, and have been meaning to come back to it as a topic for its own video. So many topics on the list! th-cam.com/video/KpGvHpB7SQ0/w-d-xo.html
@@EngineeringwithRosie can you bring someone in to explain the likely reaction of the oil industry to that, please?
Thanks Rosie, I’m hooked! You have a new subscriber and a better informed consumer!
Thanks for this. Excellent summary as usual covering a lot of ground with precision and keeping it real.
I work in low-carbon cement research. There's one clarification I'd like to add to a mostly good explainer: the limestone>lime calcination works essentially in reverse over the service life of a concrete structure; CO2 - about 30% of emissions used to make the concrete - is absorbed by the concrete over its life (also: geopolymers use a lit of industrial chemicals, which use enormous amounts of energy- the emissions are not in the cement, but the ingredients). Also, CO2 injection is likely to have unintended consequences on the longevity of concrete structures.
A further way to reduce total cement use is to have longer lasting concrete structures (ones that don't need to be torn down after 30 years).
There's a lot of research and innovation in this area, so watch this space!
Thank you.
CCS reminds me of fusion reactors.
A lot of building codes have material requirements instead of performance requirements for the amount of concrete to protect the steel reinforcement. You have a core of steel-reinforced concrete on the inside that is actually load-bearing, which is surrounded by unreinforced concrete to protect the steel from water intrusion and rusting, so reducing concrete usage for a given structure is more about preventing water intrusion rusting the steel reinforcement.
The most promising technique that's easy to scale tomorrow is switching from rebar to chopped-up steel fibers mixed into slabs that prevent the concrete from cracking so water can't get in. That allows you to reduce the floor slab thickness by 40%. I think steel or polymer fibers mixed in as a supplement to traditional rebar can provide a similar benefit for beams and columns. You can also sidestep the problem with some geopolymers that are inherently completely waterproof.
The other great way to reduce concrete usage is switching to alternative materials. For buildings, using engineered wood instead of reinforced concrete for either the whole structure for short buildings or just the floor slabs for tall ones dramatically reduces concrete usage, and reduces building weight, labor, and construction time too. Civil construction tends to already use reinforced earth instead of concrete wherever possible because it's cheaper and the scale is so huge, so I don't know how much more substitution exists on that side of concrete usage.
Makes me wonder how effective chopped/modified waste plastic would be for rebar replacement. Side benefit might be less concern about water intrusion.
@@koyamamoto5933 the plastic fiber reinforcement isn't structural since most plastics aren't very strong, it just reduces cracking and spalling, which protects the structural steel rebar from water and reduces damage from thermal cycling. recycled thermoplastic plastic might work if you can spin it fine enough.
@@thamiordragonheart8682 recycled polyester (2 litre bottles etc) can be spun fine enough that individual strands aren't visible to the naked eye but that introduces problems like silicosis.
"B1M" channel on TH-cam (the largest construction engineering channel) has been looking at engineered timber buildings for a while
@@koyamamoto5933 plastic reinforced concrete is possible but works in a very different way to steel reinforcement - you can make car springs out of it!
Love this! Made it so much easier to understand sometimes dense engineering topics for those of us with a passing interest in learning things like this!
Great video again!
Did anybody else's heart skip a beat at seeing those 'O2 atoms' at 3:23?
I think the usual issues applies, current standard practice is cheap and easy, well developed, known and trusted, and, it's a pretty powerful industry.
We could replace a significant part of the concrete we use with wood, we can make wood constructions resistant to things like fire, fungi and pests. Building with sustainably produced wood locks that carbon for the lifetime of that building, at least. The carbon content of dry wood is typically higher than that of CO2.
Humidity used to be a severe issue for wood buildings in year round warm climates that weren't very dry, and very dry areas usually don't have a lot of fast growing trees.
Wood definitely has limitations, it's typically not useful for foundations, or constructions in water, but that doesn't mean we can't use it where it is about as good as, or better than concrete. Wood have some practical advantages over concrete, it's much more insulating, also lighter for the same strength, and unlike concrete, acid rain dosen't dissolve wood. Increased CO2-levels will decrease pH of rain, this is already an issue in some areas, not a huge issue, but with increased CO2 levels in the atmosphere it can become a serious issue in some cases/areas.
Gracias
I'm not a chemist, I'm a builder. I know that cement is a relatively new building material, only used for about one hundred years. That means that most buildings don't have any cement in their structure, yet these cement free buildings have lasted for hundreds of years.
I love your work, thanks xc
Great video!
It is great to hear the optimism of this survey of what _could_ be done in an industry with such feet of clay that it is resisting any change to its massive momentum of continuing to expand the fossil emissions it creates, and such duplicity that it greenwashes with every word when it speaks of its plans at all.
Geopolymer and sequestration of aggregates are cement's two great hopes in a world that needs everything to become net carbon negative, and rapidly -- at least 2% of today's level less fossil emission per month down to zero by 2030 to avoid Lahaina repeating over and over again. Unlike Ordinary Portland Cement (OPC) and most other cements, geopolymer (alkali-activated metakaolin) tolerates charcoal (or 'biochar') as an aggregating material well, and can be made substantially lighter and better insulating concrete with little loss of strength, cheaply. This is a good way to sequester the wood waste from all those trillion trees the world needs to plant by 2060 to prevent the trees from decaying into methane.
While carbon curing has a nice sound to it, the present practice is for governments to subsidize carbon cure cement that otherwise would never have been produced, thereby creating fifty times as much CO2 emissions from fossil (which all limestone is). In reality, carbon cure is a dead end: all cement eventually cures over time, so the gain of 'carbon cure' is temporary and dubious.
Building out of engineered wood, however? That's as good as it sounds. Especially increasing population density of cities with engineered wood buildings in walkable neighborhoods.
Keep up the great work.
I work with slags, and GGBFS, which can replace GP Cement is already being used at about 40% of the concrete binder blend and can be higher, up to 100% such as in some geoploymer blends.
Additionally, there is a bunch of good research going into if BOFS or other steel slags can be used to both capture/sequester carbon and provide a cementitious material.
As you say, blast furnaces are likely to be phased out and the newer technologies are not mature enough to know if the byproducts will be useful for cement, but we have a couple of decades before this (at least) where we can act based on current technology. The steel slags side of things is likely to hang around for much longer and it's showing good promise to supplement cement while also sequestering CO2
Thank you.
It's not just cement that is an issue.
180 litres of water are used to make a metre cube of concrete. 47% of this water remains held in the concrete.
Fifty billion tonnes of aggregate are extracted from beds, banks and floodplains of rivers and lakes. Vietnam’s Mekong Delta is disappearing.
We need to reduce the amount of concrete used. Have a look at a product called Stratadune that uses a lot less concrete.
Excellent work again Rosie, thanks.
Hi Rosie I am fan from The Netherlands. I think you missed SaltX from Sweden and Aussie Calix Limited with their doughter from Europe: Leilac. Have a nice day 😊
Recycled plastic -in-situ raft slab form-liners can be used in on-ground slabs to reduce the amount of concrete used in these applications. It can according to supplier data reduce the overall cost of am in-situ slab by 15-20%. As per your video when you add this to a process from Carbon Cure you are potentially looking at reductions in concrete volume. These two reductions might go some way to balancing out the increased in production cost of the new concrete mixtures thus allowing for a faster transition away from existing concrete mixtures.
Awesome video. Whenever I talk about climate change with people, especially those interested, I try to draw focus to these silent killers. It's been awhile since I've heard any progress updates so this video was very appreciated :)
Wow! Great explanation of concrete and cement and how the production of cement emits CO2. Nice to know that there are at least some promising solutions on the horizon for reducing that CO2.
Your breakdown was awesome as we have come to expect. I have what may seem a "silly question"; how much CO2 is lost to the atmosphere via soda pop? I mean it has to bee almost total, as when you open the container and the pressure drops to atmospheric, and bubbles of CO2 start rising furiously. This and few other ongoing situations make it very hard to see "serious" in a lot of both US politicians as well as world wide. We literally have people canning and selling CO2 infused drinks by the millions. That has to be adding to that gosh awful total. And even if we stop this, carbon capture of all the "trash" we can get out of our air is good for every living organism on today's earth. I can also see some sort of world organization to determine which countries are not abiding and announce sanctions in the trade areas. Otherwise, I don't see success for any of us.
Hi Rosie. There’s another way of reducing CO2 from concrete. In many cases, it’s possible to replace the steel rebar with basaltic rebar. BR can be produced with renewable energy and basalt is as you know, the most abundant mineral on earth.
Theres a couple of companies developing very high temperature electric heat using turbines to compress some inert gasses, I remember seeing a couple of names on IEA page about emissions from concrete
Awesome! Once any of those scales up, we just need an alternative to sand.
Great video!
Thanks very much for the informative video. Seems like this process is in some ways the opposite of mineral carbonation? Can calcium carbonate be used more directly in building materials?
There is also the possibility to replace concrete, where concrete is not needed, by wood. I do not talk about the matchstick houses built in the USA (mainly 1.5 by 3.5 inch), but houses like they are build for example Norway using beams instead of sticks. You can produce houses that stand up to heavy winds and earthquakes out of timber. Regarding multi story buildings from timber, they are reaching 20 floors.
Timber buildings are good as long as there is enough timber grown and we actually sequester carbon at the same time. A lot of the timber would be used as CLT or laminated beams. Both can be adjusted to in what direction the strength is needed and produced to needed sizes for each project.
Establish a global, escalating, predictable carbon price (call it a "dumping fee") and watch all of the most practical new ideas accelerate. Decisions at every level need to be based on carbon impact.
Cool. Need to push on multiple fronts.
Of course, you can always revert to lime mortars in many applications. Lime mortar sets through carbonation rather than hydration thus absorbing carbon dioxide from the atmosphere. As you point out calcium oxide is made from limestone at only 1000degC which is much easier to achieve in an electric furnace. As you say, this temperature has already been achieved in Finland. Capturing the emitted carbon dioxide from an electric furnace is a little easier. Lime mortar is carbon negative at point of use.
9:47 - there's a process by ThyssenKrupp that heats kiln using methane burned in oxygen produced on-situ instead of air, making CO2 much more concentrated in effluent gas and so easier to capture. After a series of pilot plants, the plan is underway for an industrial scale installation in Našice, Croatia. The captured CO2 will be stored in nearby saline aquifer.
Building with bamboo, hemp, and wood will remove a lot of carbon from our atmosphere, and hempcrete walls will lock up the carbon for hundreds of years. Producing lime in electric kilns powered by renewables is another positive for using these building materials. We should be insisting that these building materials are used in earthquake zones like Turkiye.
👍
great summary, though I would add Rondo energy to your list of heat solutions. They've been able to generate very high temperatures using electric heat batteries - not quite to Cement heat yet, but they are working on it.
Rosie, have you explored the properties of geopolymer vs Portland cement?
What about using other materials like hempcrete for example instead?
Lime based concrete or mortar is different than klinker based in that it reabsorbs the emitted CO2 over a couple of years, turning back to calcium carbonate, making it truly carbon neutral if cooked with renewable energy.
Unfortunately it's an order of magnitude less resistant and doesn't harden in wet conditions (so called hydraulic lime does harden wet, but uses the same chemical reactions as klinker, so it doesn't reabsorb the CO2).
I'm sure research could be done to increase it's strength so it could be used anytime wet hardening isn't required.
Also look at the recent research apparently solving the mystery of Roman concrete
Are there substitutes for cement?
Rosie, please also talk to First Graphene, an Aussie listed company in Perth but the CEO Michael Bell is in Singapore -- the Graphene scientists are in Manchester
your co2 budget should mention that when lime(CaO) cures, it converts back to CaCO3 absorbing CO2 in the process.
What if we combine different known processes with the production of cement? I have an idea which includes a pyrolysis chamber and plastic waste, which still have not been solved properly.
My idea is to run the process of making cement and use the process to heat up the plastic waste so it turns into gas. Since 95% of plastic is made from oil, there is a huge benefit from using the energy in plastic waste to be used a part of the heating process.
One pyrolysis chamber can turn 50 tons of plastic waste into gas or oil per 24 hours.
A by-product of pyrolysis is, it ties the co2 in plastic in carbon black, which can be used in the process of making cement. Or enhancing the soil farmers use to for soil enhancement.
By doing so, we solve some of the problems of cement production. And a part of the need of energy.
But we need to figure out how to channel the heat from cement production to be used in heating the pyrolysis chamber (which needs 500 degrees Celsius)
I think the combination is beneficial.
Kind of brings up an interesting issue.. In studying cement from ancient Rome a fairly recent discovery regarding its strength and ability to last has been shown to be that it is, I don't remember the exact term, bit it's something like, "hot pored". This means that the Valcium Carbonate is still in the process of conversion, unlike Clinker, and it actually develops crystallized bits inside the material. When cracks form and water finds its way in the water dissolves these crystals, which then redeposit in the cracks, as it seeps back out, sealing the cravk and restrengthening the material.
So... do any of the alternatives exhibit this trait, voukd be made to, etc., or are any alternatives we develop going to have the literal same problem as, ironically, all modern cement, in that they cannot self heal, and are thus actually less structurally sound over the long term?
Hard science put simply. Thanks
Strawbuilding which use straw for thermal isolation panels could also be interesting in carbon negative building
You should look into CarbonCorp/C2CNT and STEP cement
Very good technology overview. Another way to reduce world wide cement production and CO2 emissions: use laminated wood as in CLT or GLULAM for buildings upto 10 stories high. Trees capture CO2, so there is a double benefit!
I had this discussion with my eco issues professor in a tutorial , he was excited about the possibility of using magnesium carbonate for carbon storage but I couldn’t find any large scale magnesium ores that are not carbonate based minerals then neither could he.
Majority of family houses in Canada are wooden. Except for the foundations.
Really interesting, thank you. Books, wood, wind, composites, Danish?
She used to work in Denmark.
As with many other areas, a carbon tax is needed to make the processes viable. Cement is too cheap right now.
God this is such high value climate content.
Thanks Rosie
Thanks Rosie a great video! When cement cures it absorbs CO2 so when you look at the whole lifecycle. How much is absorbed vs emitted?
Love your videos Rosie. Yes we should move away from cement & concrete there are many lightweight alternatives that are recyclable. We have invented a new building system called CLIK that uses NO Concrete and NO timber.
Ms. Rossi, you have a couple decades of experience. You very young lady. You start when you were 10?
Love your videos. Very well put, very informative.
I am 40 😊
What do you think of using coral for cement, bolstering it with graphene, and using hydrogen to make the rest of the ingredients? (energy usage)
If cement is cured/solidified it will absorbe similar amount of CO2back from the air, is it not counted? Only when it is produced?
If you use carbonacious materials as an aggregate in concrete you can also make it carbon negative. Like hempcrete, woodcrete, plasticrete etc..
Is there a number for what carbon price would make the best alternatives economically attractive next year? If the carbon price makes a transition in cement production immediately attractive, how long would it take to roll out those technologies in places like India and Africa, which will be ramping up the development of concrete infrastructure and housing for decades to come?
I don't know the answer to that but I did hear recently that adding CCS to traditional cement manufacturing would approximately triple its cost. Cement is such a cheap material, that's why it's so widely used and it will make it really hard for new technologies to compete on price.
Add in that modern concrete doesn’t last. Roman concrete last thousands of years, our concrete is good for a century or so. A lot of early 20th century classic buildings are nearing the concrete expiration date…
Another option worth considering as a cement alternative is large-scale wood construction, which not only avoids concrete and steel production but also acts as a long-term carbon sink. The kind of constructed wood materials they use like cross-laminated timber (CLT) can actually be just as fire resistant as steel and concrete. th-cam.com/video/1N0tdEc4oTw/w-d-xo.html
Neocrete seems to be looking hopeful as an additive to reduce cement quantities without needing a fossil fuel source. Sources from volcanoes in NZ I believe.
Should be called Paleocrete:
Pozzolanas such as Santorin earth were used in the Eastern Mediterranean since 500-400 BC. Although pioneered by the ancient Greeks, it was the Romans who eventually fully developed the potential of lime-pozzolan pastes as binder phase in Roman concrete used for buildings and underwater construction. Vitruvius speaks of four types of pozzolana: black, white, grey, and red, all of which can be found in the volcanic areas of Italy, such as Naples. Typically it was very thoroughly mixed two-to-one with lime just prior to mixing with water. The Roman port at Cosa was built of pozzolana-lime concrete that was poured under water, apparently using a long tube to carefully lay it up without allowing sea water to mix with it. The three piers are still visible today, with the underwater portions in generally excellent condition even after more than 2100 years.
-Wikipedia
I don't like all those concrete skyscrapers to begin with. Perhaps we could build mathematical structures which are strong without needing much material? And other materials should be used. Perhaps fiberglass sheets and a lot of "sticky polymer" could be used. Perhaps going in the ground could be an option too since the structure would need less support there. That would save on heating and cooling too. I always feel too that renovation should be preferred but now they find it easier to smash everything down. That works easier. Yes, but we need interlocking panels etc to cover old walls etc..
I am in a building made out of heart pine and plaster. Plaster is carbon negative because it absorbs carbon as it ages.
I learned something here too. Thank you.
You finished by saying we need political initiatives to make things work. I agree. The cheapest way for all is taxes on all carbon that may end up in the atmosphere. But many resists that in a very dogmatic if not religious way - what can we do?
Great in depth discussion. I would love to see a discussion on the relative amount of steel in a wind turbine and an oil well.
What is the main thing preventing the scale up of magnesium-based cement?
fashion
Portland Cement has been on the market less than 200 years (1840s) but cement & concrete have been in use since before the Roman era. Which type of cement is popular at any one time is purely fashion.
At 3:43 you are talking about CO2 emissions while showing natural draft water cooling towers with ‘water vapor’ drifting out of them. 🤔
I was unsubscribed to you. I did not do it… looking forward to x. Hopefully they do a better job than TH-cam.
What did the Danish dictionary in the video have to say on concrete?😮
Concrete er "beton" på dansk 😀
This entire analysis seems to ignore the latest science that when curing concrete re-absorbs a good portion (25-60%) of CO2 released from the limestone. If we can capture the CO2 during production it seems like, concrete could become a useful carbon sink.
We use so much concrete that there are sand shortages too.
7:55 “.... level required by 2015.” ?? 🤔
1:01 No, that doesn't mean we need to find a way of producing it without the emissions.
Don't forget additives (to the cement, making concrete). If you add biochar from (truly) waste biomass, you can get to negative emissions. There's a company already doing this.
I wonder how the rediscovery of Roman cement recipes will affect the carbon footprint of concrete
Good video, but I feel like you should have at least said something about hydrogen as a replacement in heat. Hmmm