Why isn't Roman Concrete used today?

[@1TakoyakiStore]

When I was visiting Indonesia I noticed that the modern methods used in masonry construction differed from those in the USA. When I asked around apparently their concrete was particularly strong and cheap compared to elsewhere in the world. Turns out they too like the ancient romans would add volcanic ash to their cement.

[@AngkatanNamwaran]

Same with the Philippines, the volcanic ash from the 1991 Mt. Pinatubo eruption is being used in construction today.

[@habibainunsyifaf6463]

I mean... We're full of volcanoes, it's cheap enough to use.

[@Michael_Brock]

There is the other thing, self healing concrete. Roman concrete was NOT 100% cured. Less adequate mixing. So if cracks appear (earthquake or storm) the concrete will carry on curing repairing the cracks. Edit clarification.

[@ObsceneSuperMatt]

@@Michael_Brock Using quicklime in the mix creates the clumps that react to water and reseal cracks. Using seawater is also part of the formula.

[@Wyattinous]

What a well rounded and succinct explanation to this topic, your final words even more so. The methods were amazing for there time, but methods change and adapted to the project at hand. I’d love to see Roman concrete utilized to build structures again, and people finally finding out how it was made had me excited.

[@frank_zapping]

The Building of the thumbnail was built in 1936, it is called "Palazzo della civiltà italiana", also known as "Colosseo quadrato" (square Colosseum)

[@robertgiles9124]

aka the Cheesecake building; I lived a block from there in 1962 in EUR

[@EinChris75]

I visited that place about 20 years ago. It was a hot summer in Rome.

[@ralfjansen9118]

It stood empty for many decades until the fashion brand Fendi took residence there . Until today, you can read the proud fascist inscription there: All the neighbourhood was erected by Mussolini to the world exhibition of 1940 which had to be canceled because of the war.

[@CyberMatt85]

Made by Benito Mussolini

[@TheAtomoh]

Na cacata fascista in poche parole

[@MarkACarroll]

That building in Chicago is indeed a hulk of a space. Solid hallways, but not claustrophobic when one walks it. Open to the public as well. First floor has small shops.

[@iamgermane]

No earthquakes in Chicago either.....

[@Nyx773]

@@iamgermane Actually there are earthquakes in Chicago. Indiana and Illinois lie in the most seismically active region east of the Rocky Mountains. This region consists of two main areas, the New Madrid Seismic Zone and the Wabash Valley Seismic Zone.

[@iamgermane]

@@Nyx773 Yes, the New Madrid zone is expected to destroy St. Louis. In the early 1800s there was a huge earthquake and it changed the course of the Mississippi!

[@watching010]

how did finance system in rome work? how did they pay rent? where loans with intrest a thing back then. How did companies work in that time? And how did the companies get financing for growth and new projects?

[@MercurialStatic]

I’m sure there is a book for that.

[@dodiswatchbobobo]

Diversification, innovation, and growth weren’t really priorities among Roman businesspeople. It was really just a series of pyramid schemes until mercantilism really took off.

[@Sam97979]

Slave labor made a lot possible, as well as looting whatever you need from someone else. Why pay, when you can just take?

[@antoniousai1989]

Companies did not exist at the time; it was about aristocratic members with lots of money from their land ownership. The concept of a company as an economic institution is recent and started in the Middle Ages. Loans were a thing, and so was interest; loans have existed since the Mesopotamian era. I don't know much about rents, but I remember that people did not rent apartments in the big insulae; they usually rented rooms for the entire family of commoners.

[@TheRealMjb2k]

I believe he has answered at least your second question in a video. People paid rent annually and usually in the early days of July. That's what I recall at least.

[@billcampbell9611]

Modern concrete does NOT need air or CO2 to “harden”. The water chemically reacts with the cement (hydrating). This is an exothermic chemical reaction (it produces heat). Modern concrete can indeed be poured and set under seawater (it’s a challenge but possible). The exact properties of modern concrete are adjusted according to specific needs by the addition of admixtures (additives to control various properties). Extremely strong and durable concrete can be produced if desired.

[@slimjim2584]

Modern concrete is mostly fly ash because it was historically cheap due being a byproduct of coal plants. With less and less reliance on coal in facor of oil, alternates will need to be used going forward. Maybe something better can emerge?

[@kyleanuar9090]

I'm using this type of concrete for waterproofing jobs and know they're used annually by underwater bridge pylons maintenance filling up cracks. They're super hard when set but a bit expensive

[@timothybayliss6680]

I was going to comment this. I have never heard of CO2 being necessary for cure and concrete made with portland cement will cure underwater without issue. You can just dump it underwater and it still cures.

[@danlowe8684]

@@slimjim2584 Fly ash only substitutes a portion of the cement used in the mix (roughly 20% depending on use/mix design). It also has plusses and minuses. It does not generate the heat that cement mixes do during curing, so cold weather use can be an issue. Also, if high-early strength is required (such as a business driveway entrance), it should not be used. It will likely gain more strength than 100% cement mixes over time (due to less water being needed), but it is a slower process to get there.

[@FekDindad-xy9vz]

No. But the lime based mortar he was describing does.

[@marcusmoonstein242]

The problem with regular modern concrete is that it's porous, so water can seep into it over time. This eventually corrodes the reinforcing, leeches soluble components out of the concrete, and causes damage when the water expands during freezing. Fortunately we now have many additives that can solve all these problems. Obviously these additives cost more than regular concrete, but we can now make concrete that is far superior to anything the Romans had.

[@iamgermane]

There is a structure out in Colorado built using something similar to Roman concrete.

[@ObsceneSuperMatt]

Also, iron rebar. The ancient greeks and romans would plate the iron with lead, but these days everyone is terrified of lead. Time will tell if polymer coated or fiberglass reinforced concrete will hold up. Normal iron rusts from water, and rust causes expansion in a confined space, which cases cracks.

[@jay-by1se]

I understand your point but in a way I disagree. The lime in the Roman concrete has proven itself able to last two thousand years. Modern concrete can not do that.

[@latlatko]

@@jay-by1se because it doesn't need to. There are many other considerations beyond lasting a 1000 years. But to say we couldn't make it so is just not true.

[@Dominic_LaSalle]

@@jay-by1se survivorship bias. you can clearly see all the structures that survived, but none of the ones that didn't

[@alimanski7941]

That ‘answer, not a solution’ sounds like it came straight from Garret’s teaching days

[@XDarkGreyX]

There are no solutions, only compromises

[@aldrinmilespartosa1578]

​@@XDarkGreyXthats a dillema, not a problem.

[@ae2948]

Is that why he's such a great teacher? He used to BE one ?

[@alimanski7941]

@@ae2948 taught in universities, yes

[@wfelixluck]

A Monadnock reference is always appreciated. I see this building each weekday, as I work in Chicago's Loop. Ironically, this building's ground floor features a fine mosaic featuring tile drawn from an Italian quarry.

[@tehuberskillz]

I want to thank you for all the information you provide for us, thanks to your channel my recent visit to Rome was far more exciting and knowledgable than the previous one, it changed the depth and meaning. Im so glad that we live in times where such channel exists

[@EPWillard]

I feel like we often get carried away with ideas of what could have been if we stretch things to the limit that we forget that they did things that were actually practical. it's really amazing when you look at how much we have advanced in the last century-and-change of building tall stuff and how we sometimes forget that when we assess how impressive things were.

[@GrooveSpaceArk]

It supports this channel which is a monument in its own right

[@monkaeyes3417]

huh, very useful information as a geophysics student. Was not expecting that.

[@dingjo5027]

awesome content Ryan, I love this speculative topic and the different practical perspectives you take on it. Really is a great piece of work and I love how you break down the properties of roman concrete and explain the strengths and weaknesses of it and other building materials like travertine. I think that roman engineers even discovered how to make roman concrete strong by trial and error is a profound demonstration of their resourcefulness.

[@AO-qy8fp]

Woo! Told in stone! One of my fav channels.

[@softekguy1]

Dr. Ryan , thank you for giving us this insight, I have your books and enjoy your work.

[@brucermarino]

Great research and analysis! Thanks!

[@arrjay2410]

I always find your reports fascinating. This one doubly so, since I am always interested in old technologies and how they were manifested.

[@danielintheantipodes6741]

I had always wondered! Thank you for the video!

[@geoffreymclean3218]

Love this one. Keep rewatching to catch details I missed the first time or two. One thing about the “insulae” or apartment buildings. I’ve read about how in Rome, they would extend upper stories using wood construction. Unlike today, the poorer you were, the higher you went.

[@kutter_ttl6786]

I suppose in a world without elevators, that does make sense. Can't have the rich climbing too many stairs.

[@OceanHedgehog]

Such a great video and channel. Clear and concise.

[@danukil7703]

Ooh, what a fascinating question!

[@chrisleblanc581]

I listened for 3.5 min to see if you would include the real reason for Roman cements longevity. It had nothing to do with volcanic ash per recent science publications. It had to do with lime not being milled too finely. When a crack occurred, the large grains of lime would hydrate, swell and fill the developing crack with a built in bandage of sorts. And the fellow below is correct. Co2 nor air are required. I’ve set many fence posts with cement with no water added. You would be surprised that you can even make sidewalks w out adding much water. The compounds used to make cement are extremely hygroscopic, meaning they like to bond with water so much they can pull it from the air or earth surrounding them. Calcium and magnesium salts have to be cooked in an oven to drive this moisture off of the anhydrous salt is wanted and then stored in air tight containers. Once opened though they again naturally pull moisture from their surroundings. This guy does not seem to understand the chemistry involved at all and is just parroting what has been thought and said by others in the past. Now, I’m going to walk down the street and wade into the lakes public boat launch and stand on modern concrete that was poured and set in brackish water and think. You know, we really need to teach people to read primary sources so they can better learn to call bs when “experts” give their opinion.

[@chrisleblanc581]

Ok. This makes sense. The dude has a PhD in Greek and Roman history. To me that basically means he learned to write speculations based on speculations of others with a few facts understood to varying amounts in a coherent and grammatical fashion. I’d bet he had very little hard science courses at all.

[@shelbylacouture3232]

Lol, I also watched specifically to see if he knew this.

[@VladamirOffPutin]

Naturally hydraulic cements would never be able to pass the muster in modern construction projects. In modern times, projects are driven by cost and schedule. Even if sufficient quantities of Roman cement could be produced, the slow setting process would make the prospect of use DOA. Also, Roman cements do not achieve high-early strength required or the final compressive strength required by modern building codes. These historic materials, and there are many, are best suited for the restoration of important buildings that are not compatible with modern materials.

[@VenturaIT]

it's not to do with the milling granularity, there are two types of lime... hydrated lime and quick lime... quick lime is reactive and is calcium oxide (CaO) and reacts with water to produce heat and make hydrated lime (calcium hydroxide) which is not reactive... modern concrete/cement uses hydrated lime so there are different chemical reactions happening than Roman concrete that used quick lime... the quick lime was mixed rough into the mix so it wasn't all reacted so if water got into it or it cracked then all that would happen is that it would react more and form more concrete... this is the difference, not really just the milling size... they left bits of unreacted quicklime in their concrete...

[@RabidWombatz]

Also he says normal concrete cures from CO2 in air, which is 100% incorrect.

[@jeremyd1869]

Fascinating! Thanks, Dr. Ryan.

[@user-to9ge8ii9n]

Didn't know this was a question I needed answering, but when I read the title... ❤

[@davioustube]

Beautiful video essay

[@CyberMatt85]

Very informative!

[@nomadicoasis9260]

Well that answers a question I've had for years... Thanks

[@brick6347]

Concrete is certainly a pretty amazing material, but on its own, it can be pretty ugly, especially in places with gloomier climates. I like the Roman idea of hiding it away behind a nice layer of masonry. I used to live in Warsaw, a city shaped by a post-war love of modernism and brutalism. Perhaps it's just a style that's too old to be modern and not old enough to be valued yet... but I don't like it!

[@red.aries1444]

The Romans didn't hide the concrete with masonery because they thought the concrete was ugly, the masonary was a technical necessity. If you pour Roman concrete just like in the cuppola ceiling of the Pantheon, you have to wait several years for the concrete to harden enough before you are able to take down the formwork and scaffolding otherwise your wall would collapse. By pouring the concrete between two thin brick walls you need much less sheeting and the wall is much sooner stable enough to build higher, therefore you can build much faster. And even if you would encase the Roman concrete and wait long enough until it settled, it would look mostly much better as the most of the time very grey brutalist buildings. Roman conrete is through all the rubble used in it, much more colorful and less grey. If you smooth the surface it is more or less like terrazzo. You can have this with the right modern concrete too, but that is very expensive.

[@Bob-t8l]

Was brutalism just a bunch of architects trying to make the most insane concrete bunkers.

[@jaimepujol5507]

@@red.aries1444 they did however use marble to hide the concrete and masonry, for fancy buildings at least

[@PistonAvatarGuy]

Brutalism + lots of greenery can be beautiful, imo. When surrounded by greenery, the buildings create an effect like stone mountains in nature.

[@AndrewBlucher]

The Palace of Culture and Science is the biggest offender.

[@melizen2]

So interesting - thank you!

[@Sarnarath]

This is the content I'm looking for👍

[@leviosssa5843]

this is terrifying, i LITERALLY asked myself this question 30 minutes ago, man you're good

[@DuncanL7979]

He knows your thoughts.

[@richardglady3009]

Neat video. Thank you.

[@fuferito]

The Tower of Hercules in Galicia, Spain isn't technically a skyscraper, but it has similar dimensions and form and it was built in Roman times, and it is still standing.

[@AdiSneakerFreak]

Another enjoyable video ❤

[@SleepyPotterFan]

Me, sitting in my concrete vault, first floor dungeon, looking through my slit windows at those fools in their modern skyscrapers: “At last, I can begin to live like a human being.”

[@Trenz0]

Engineering meets History. This video was made for me!

[@JohnCaldwell993]

Roman concrete is an example of just one type of ancient "geopolymer." Other cultures, like the Egyptians and Incans, had their own recipies. Geopolymers are quite different from modern "portland concrete." If we simply focus on the chemistry, we will find geopolymers an excellent material for modern applications including skyscrapers! There are many companies working on modern geopolymers for industrial and commercial uses. Perhaps a video should focus on how the Romans discovered how to combine the ingredients in the correct order to create a type of carbon-neutral concrete that has lasted 2000+ years?

[@TomTom-em2qy]

A Venetian company called MGN have a very long term study on this, have engineered a good replica lime and pozzolan line of products. They're available on the UK market and are honesty as mind blowingly good as one would imagine. I use them a lot, they're expensive but magical.

[@shawnsg]

Why would you focus on that topic? The Romans didn't set out to create something that would be carbon neutral or knowingly last several thousand years.

[@JohnCaldwell993]

@@shawnsg To be clear, I mentioned those two qualities as an advantage to us (as opposed to Roman design features). Portland concrete, which we use everywhere today, was only invented in the early 19th century, and requires manufacturing technology the Romans did not have. Portland concrete makes up 9% of the world's CO2 production and lasts an average of 25 years before needing replacement. Whereas the Romans discovered a formula requiring no complex manufacturing, 80% less CO2, and last an average of 4x longer. They did that 2300 years ago?! I think a video that focuses on how that was discovered and applied to broad-scale block pouring for infrastructure would be fascinating. It's only within the last 20 years or so that we developed the microscopy technology to distinguish between real stone blocks and geopolymer concrete poured blocks -- I think we're going to soon discover that this tech was used a lot more than we realised.

[@TacticusPrime]

Engineers and architects design structures within *budget* and timeline. They could absolutely build a structure to last thousands of years, but that wouldn't fall within the budget or timeline.

[@ΕρνέστοςΣμίθ]

@@JohnCaldwell993 The problem with Roman concrete is that it sets very slowly compared to modern portland concrete and that it uses natural pozzolans which were widely available in Campania, Italy and Santorini, Greece but are not very common in most countries. Fly ash is a good replacement for natural pozzolan but not as good as the real thing. Unless we found a way to produce pozzolans artificially, the world's deposits of pozzolan would soon be depleted.

[@anthonysaunders345]

Of course, if you used Roman concrete to build a skyscraper the same way as we do with standard concrete, all those problems mentioned would go away. Steel superstructures are used for a reason. The problem with standard concrete is that is doesn't last nearly as long as one would think. It is vulnerable to degradation from such things as H2SO4, water and salt, as well as flaking from freeze-thaw cycles and cracking instead of flexing under load. Pozzolanic ash in Roman concrete was only part of the story. What is fascinating about Roman concrete is its self-healing properties due to the presence of calcium carbonate (lime) clasts around a milimeter in size. Also, by using quicklime, it set at far higher temperatures, making the clsts brittle enough to give them their self-healing properties. These high temperatures had another benefit.The concrete set much quicker, accelerating the construction process.

[@loisrossi841]

Thank you.

[@joshuakirkham9593]

That was good, I am knowledgeable of the fact that we often look on previous eras with rose-coloured glasses, so breaking down this problem was helpful to dispel a myth.

[@therealhellkitty5388]

The interesting thing about Roman concrete is that it continues to cure as long as it is in situ. and it will cure under water. It is also self-healing.

[@Dragonogrado]

7:39 Breakwater at Two Harbors, Minnesota, to protect the iron ore (taconite) carrying lake freighters in Lake Superior

[@greatnorthernhans3319]

I'm glad someone else noticed this! I wonder how he came across that particular structure as an example?

[@Dragonogrado]

@@greatnorthernhans3319 When I was walking it recently I wondered how they built it. His photo shows those circular concrete pours on the lower right where boats moor for protection. Were those poured first since they probably go deep into the bedrock, and then they poured the rest of it?

[@elingrome5853]

that monadnok building in Chicago is beautiful!

[@kaifengwu6565]

As an architect I would like to propose iron reinforced travertine on corners and load bearing exterior columns, paired with Roman concrete vaults between those columns to stablize them laterally, and one additional medial layer of concrete columns and vaults to sablize them in depth. Then, all flooring will be wood over wood truss. This is somewhat similiar to the sections of many roman basilicas. I'm sure there would be ways to optimize the structure, lean on the strengths of the selection of materials to create larger windows and less ristricted living spaces.

[@thebosley4103]

babe wake up toldinstone just posted!

[@Chung_Wang]

I can't believe I discovered such an amazing channel via a Maltese Trackmania streamer.

[@rachel112263]

OMG!! I'm so glad I found you. Your knowledge of Roman building practices is invaluable as you have introduced me to Travertine, formed when high levels of groundwater contaning an elevated concentration of dissolved carbon dioxide come in contact with LIMESTONE, and similar deposits formed from ambient temperature water creating TUFA, reinforces my belief that the megalithic structures and underground tunnels all over the world were built and carved out of Tuff and Tufa which are soft materials easy to carve and hard to break down. Tuff, volcanic ash that can form a similar stone as granite but contains no fossils...and Tufa, such as stalactites and stalagmites that can be dated back to the Permian period 500 million years ago when the earth was still one giant continent called Pangea. This can explain why the same type of structures were built on now separated continents. Please look into this. If anyone can give me answers, you can.

[@alexanderdeburdegala4609]

A few inaccuracies / missing facts here. All non-reinforced concrete will crack / buckle under tension, even modern concrete. Roman conrete was is far better at dealing with micro fissures because it has the ability to self heal due to it's chemistry, it's far superior to modern concrete for durability due to this, this is why Roman concrete structures are still around many centuries later. Also while pozzolanna might be scarce, the chemistry is easily replicated by using coal ash. In addition Roman concrete does not take any longer to dry than modern concrete designed for the same applications, in fact Roman concrete is not only far stronger in marine applications ( with salt water ) it sets far faster than modern concrete as well. Lastly the only advantages modern concrete has, is it's slightly cheaper, and current industries / infrastructure isn't designed around making it. ( PS don't mean this to come off snarky, I really enjoy your channel, however I am an engineer and you are a historian, so in regards to this subject I think I have the greater expertise, also a lot of the knowledge I shared here has been recently discovered, making older sources will no longer relevant. )

[@Tuberuser187]

If you used some modern construction techniques you could mitigate the curing issues with the full Roman concrete Monadnock building, we run into the same problem with modern concrete on huge structures like Dams. If you used a combination of casting the Roman concrete in blocks, poured in a sequence to make the curing easier along with some piping to carry chilled water to regulate the temperature it might be possible to do it.

[@animalfriends7595]

Garrett, I should speak up more, but please understand I love everything you do here on KZbin. Remember when History Channel was cool? I do. You're part of the modern version of History Channel. Thanks for regurgitating the knowledge that led you to a PhD right here in public where we can lap it all up. It means a lot to me. Plz hook up with all the other history KZbinrs and get the planet back on track. Stay happy and thanks for all the videos!

[@OiAcIDic]

I very much enjoyed this video, I approve of both strategies and also am more optimistic than you on the possible success of both structural scehemes. I believe, the biggest concern would most likely be the earthquake resistance of the building, a very strong possibility in central Italy, and very damaging to unreinforced masonry and concrete structures. Statically both schemes should work well but lighter damage in the form of cracks would most likely appear, but they would not be structurally relevant.

[@soteriamediaproductions6165]

I just wish they could use some of the old Roman stuff in these crappy Michigan roads!

[@michaelblum4968]

In San Francisco, Calif. a fireproof, riot-proof and earthquake-proof building was constructed in 1853; it was only four stories tall, but very sturdily built. It had some of the same issues as the hypothetical "Roman skyscraper": narrow windows on the ground level, and very little natural light. It was torn down in 1959; the site is now where the Transamerica Pyramid stands.

[@happy2b4]

Besides the structural property issues, the Roman process is not conducive to the large batches and placement operations we mostly do today. It was not forgotten. After the Romans introduced the method to England, it has been continually practiced there to this day (by the few people who know how). Though probably not the salt water version.

[@podpeopleofdestiny3915]

Do you have any books on these recipes for concrete? That would most helpful

[@mlfett6307]

I did enjoy this thought exercise. My question is, would differing weather conditions affect the structure? I know Roman concrete was used outside of Italy, but were there downsides to building with it in less temperate climates?

[@TibiHIPHOP]

The last time i was so early pompei still had the go to red light district

[@drdca8263]

What’s that? Do they sell torches with Strontium salts to make the flame redder?

[@Skaggs666]

I don’t want to build a Roman skyscraper, I just want a home foundation that doesn’t fall apart.

[@antontsau]

its the reason why modern construction switched from masonry and concrete to steel structures in early 20th century - it drastically reduced wall thickness on lower floors and total building weight. Nowadays we return back to concrete as main bearing element, no need for separate riveted frame even for 40storey building, reinforced concrete makes the job. But this idea of reinforcement (rebars, flexible steel tension ropes and so on), simple but effective, was not invented until 19th century and not developed to usable grade until mid-20 century.

[@Hibernicus1968]

I wish they would build parking garages of Roman concrete. We had one downtown near our city's courthouse that was demolished after a mere fifty years, because it had started to crumble, and big chunks of concrete fell off and damaged people's cars. Meanwhile, the Pantheon, with the world's largest unreinforced concrete dome is still standing after 19 centuries.

[@JamaicaWhiteMan]

0:30 ArcGIS colour ramp. I wish QGIS had that one.

[@KennethDelavergne]

Interesting! 😎

[@davidrabbit2239]

Sunrise Resources in Nevada have a lot of pozzolan for use in concrete

[@TomTom-em2qy]

A Venetian company called MGN have a very long term study on this, have engineered a good replica lime and pozzolan line of products. They're available on the UK market and are honesty as mind blowingly good as one would imagine. I use them a lot, they're expensive but magical. They have a flooring product called Rinzaffo and it's amazing.

[@theknowledgeco-operative6997]

NPR vibes are mellow!!!

[@TheGrinningViking]

They didn't have concrete mixing trucks, and it was easier to shovel and pack down solid concrete than trying to mix watery concrete in a barrel and tip it over. Roman concrete was strong because it was trowled, as said, rather than poured. We can still make it. We don't because pouring and reinforcing is easier and better in modern applications. No thick concrete walls for us. Oh, and modern concrete heats when it sets and can do so underwater if you plop it down thick.

[@LordWyatt]

Pretty sure I know the answer but more information is always a blessing:)

[@cvrkster]

anyone getting Sheldon vibes? "Sheldon Cooper presents fun with flags" board in the background and everything 😁

[@m.e.345]

I think I asked this question before, but I forgot the answer.. Why have the iron 'clamps' in the wall of the colosseum not been replaced? ..Would they not help to preserve the integrity of what is left of the structure in the event of an earthquake?

[@jonny-b4954]

If they built it properly you could probably go.... 6-10 stories? It'd have to be done with arches and what not though. Like most their structures. They also used concrete for the floors and foundations but block for walls. And they didn't really "pour" concrete like we do. It was troweled on. Unless they figured out reinforced concrete they would likely do blocks.

[@Nightscape_]

After all those videos by geologyhub, now I wonder how earthquake resistant ancient roman buildings were.

[@Blackadder75]

What would be the largest pyramid you could build with roman concrete?

[@-caesarian-6078]

Given how most pyramids have almost no open space inside, and they are always, well, pyramid shaped, I would say until it becomes so tall the builders suffer from hypoxia, or you run out of flat land to build on.

[@LucyKosaki]

@@-caesarian-6078 i imagine there comes a point where the pressure would be so great, the blocks get crushed into dust

[@-caesarian-6078]

@@LucyKosaki Maybe, I'm no structural engineer, but I imagine that effect is minimized by everything being pressured equally on all sides, like how eggs work when sat on.

[@ackchyually9461]

assuming σ=8,5 MPa it would be around 1250 meters

[@MrX-hz2hn]

@@ackchyually9461 Assuming a constant density of 2500 kg/m3 (it needn't be constant) and a compressive strength of 8,5 MPa, a ( constant cross-section) column of concrete would collapse under its own weight at a height of 346m.

[@theodore738]

Fantastic

[@jerrysweetable]

Good video. Spelling mistake on the chalkboard behind you. Desciption needs an 'r'

[@geraldking4080]

The Glen Canyon dam construction (1958-64/3rd US largest) used volcanic ash, as have most big dams since. They would have used salt water if they had known. River water in pipes used as rebar cooled it. +100 years to set up otherwise. They mixed it all with ice.

[@pjbth]

Acfually can you expand on that their were no companies in ancient rome...i had never considered. Did they have a legal system to seperate the busniess from the person like a corporatión. When someone invested in a company was it always a loan or profit sharing basically or did they have something similiar to shares

[@sergeigen1]

5:12 dangerous QUACKS ?

[@seanfaherty]

And it’s still fantastic content even with a little error like that

[@cloudkitt]

Very cool

[@kalrandom7387]

At the end you stated piers and breakwaters, I wonder about building a dam with it.

[@andrewjensen7454]

The Hoover Dam uses unreinforced concrete, so its similar in that sense. Pozzolana, as mentioned in the video, is also how the we get the term for pozzolanic materials which are a set of common additives in concrete that react similarly to the original roman clay, but are more common around the world. Commonly, they're industrial by-products like fly ash and blast furnace slag but can also include volcanic ash even today!

[@kalrandom7387]

@@andrewjensen7454 do you work with concrete? Roman concrete would basically heal itself on the piers and water breaks, maybe the Hoover Dam actually did use a form of Roman concrete, but at the same time there's damn failures everywhere nowadays which if they had used the Roman concrete would not happening, I live in the Eastern US it's kind of a big deal right now. Modern concrete hits his strongest point in 50 years, and then, from that moment on, it degrades, and yes, I have worked with concrete before in my life.

[@andrewjensen7454]

​@@kalrandom7387 I'm a structural engineer and have taken several courses in concrete materials science and concrete design (at the undergraduate and graduate levels), but haven't trowelled anything myself beyond a fence post anchorage of ready mix. Did work for a contractor for a bit though while in undergrad and we installed a fair bit of concrete. I've also done a fair bit of research work with dams (specifically focusing on dam monitoring), and they aren't a monolith, there are a lot of different types from concrete and arch supported to earthen embankment to clay core. Most dams are earthen embankment dams as they're much cheaper per linear foot of dam to construct. Typically failure modes for them are either abutment failures, overtopping events, or seepage failures leading to piping (water is constantly flowing out from under the dam througbt he ground, if it moves too quickly it causes internal erosion which is typically a runaway problem and can be disastrous). The thing is, none of these issues are solved by using a mix with higher pozzolanic material content. Many of them don't even use appreciable quanties of concrete in their construction! For long term durability, adding more pozzolanic materials does help resist chemical attack, which is helpful but not sufficient to ensure safe operation under extreme conditions. As for what's going on on the East Coast, it is a big issue right now and really tragic. I have family in Asheville and they've been couch surfing because their house doesn't have road access or running water at the moment. However, and this is gonna be an odd statement, overtopping of dams isn't even nessicarily a design failure. They often are, and will always be considered a performance failure by the regulators and public, but there's more to it than that from a design perspective. Dams, like all structures, are designed to meet certain service criteria which are probabilistically likely to be observed and are established by the given the owner/regulator's risk tolerance. It could be designed for a 1 in 475 year flood or a 1 in 2475 year flood, but there is always the chance that a 1 in 9975 year event comes along and the dam gets sees a service environment beyone what it was reasonably designed to withstand (Side note: those numbers seem random and kind of odd, but they correspond to a likelihood of occurrence of 10%, 2%, and 0.5% in 50 years using the standard Poission Model for hazard modelling). Same goes for earthquakes. After initial design and construction, it's down to maintenence and monitoring, but these are again primarily informed by operator budgets and willpower rather than construction material. As another note (sorry for going long), sure, concrete can degrade decades after it's placed, but that reduced strength (from peak strength) is still generally substantially higher than the 28-day cured strength. Some research papers I found indicate that it's still over 50% above 28-day strength, but I will acknowledge that how you cure the concrete matters a lot so that number will vary greatly. "Strength is essential, but otherwise unimportant." - Hardy Cross

[@danlowe8684]

@@kalrandom7387 The key to the longevity of both the Hoover Dam and Roman designs was that they are always in compression and not tension. The Hoover Dam is arched as were the Roman buildings and aqueducts. Older bridges, such as the Stone Arch Bridge built in the 1800s by the railroad in Minneapolis, also used this method but it required many piers in the Mississippi River. This eliminates the need for reinforcing steel to carry the tensile loads that concrete cannot handle. But longer spans used today require steel bars and pre-tensioned steel cables to achieve. This also leads to microcracking from flexing the concrete, which allows the steel to corrode, expand, and pop the concrete away (over long periods of time). Dam failures are rarely, if ever, due to concrete failure. It is normally due to poor design, operator error, malfunctioning equipment, lack of maintenance, silting, scouring, etc. Most dams are built with a maximum life expectancy of 100 years or less not due to the structure, but due to the natural accumulation of sediment behind the dam which leaves little room for water storage over time. This played out last week in the NC floods with 100+ year old dams where the owners did not lower the lake levels due to pressure from residents and resorts around the reservoir that depend on the water for recreational purposes. The power company also sees this as dollars down the drain when releasing the water over the spillways without producing power. By the time they did release, it only added to the natural flood waters in the already swollen rivers.

[@ElCidCampeador1994]

There are some dams build by Romans, arent big, but exist. If my memory dont fail there is one neat Zaragoza.

[@MyLateralThawts]

Any day now I expect to hear an announcement where a project will be using the same volcanic ash used by the Romans in their construction, together with the latest innovation in our industry, namely the addition of carbon nanotubes in cement, that already has eliminated the need for rebar, with the resulting structures being both strong and long lasting.

[@deanandsamAO3]

Very Interesting as are all details pertaining to ancient Rome. :)

[@SusanN-x4j]

Since seaside piers made of a variety of materials often seem to be destroyed when storms lash the coastal areas, I wonder if Roman concrete might be useful in the underwater structures that hold up the piers. There was an article in recent years that said that the chemical reaction that produces Roman concrete distributes bits of a compound that can react with water to "self heal" any cracks in the concrete that might happen in the future.

[@Chung_Wang]

IIRC it was mixed poorly so there were large chunks of unreacted lime that got activated by water filling the cracks

[@jpvansplunder]

"An answer, but not a solution." goes hard

[@CAP198462]

Fetch the popcorn and my chemistry book, this is going to be interesting.

[@xLoLRaven]

One thing you forgot to mention is that Roman Concrete can "heal" itself. Because of mixture of minerals used, specifically quicklime, cracks that form will will seal themselves when exposed to water!

[@mickvonbornemann3824]

They do sometimes put flyash in modern concrete to emulate some of the properties Roman concrete.

[@malavoy1]

How about combine our building materials with theirs? Use modern reinforcing at a minimum (I've heard they did use some reinforcing using bronze bars).

[@ellen4956]

I have been trying to get people who are in charge of preserving places like Skara Brae to consider building a sea wall of Roman concrete as a way to preserve the place from ruin. No one listens, and they continue saying it will be lost to the sea! Why don't people use this method to preserve ancient sites that are now so close to being lost forever? Skara Brae is not the only one, but no one uses this technique.

[@Momo_Kawashima]

Roman technology in a nutshell: "Bro this thing is crazy, we should-" "No need, people will know" 2000 years later: "WHAT IS THAT?!"

[@debodatta7398]

Any civil engineer can tell you modern concrete is by far cheaper and superior to Roman Concrete. The underwater thing is so ridiculous

[@CyberMatt85]

I was reading that the colossus of Rhodes used a metal framework for support so the idea that you could build tall structures using metal was known to the ancients, too bad they didn't implement the notion on a grand scale.

[@joshuayang0331]

what if, for example, we use roman concrete to replace modern concrete but maintaining the steel structure and other modern building techniques, I'm quite curious about whether it is do able and would it make it last longer

[@vincentmichael3338]

Nice

[@BlaBla-pf8mf]

Romans could have built some epic castles.

[@recentparty8369]

Big up to darmon antonini ...

[@honestopinion6711]

ryans calming voice....love it

[@billsmith5109]

Are rebar and Roman concrete compatible?

[@lipingrahman6648]

There is much interest these days in Roman concrete, it does have some advantages over the concrete used today.

[@vanivanov9571]

I'm annoyed you didn't cover using it for roads, which is what most people think of.