My interest in Ancient Rome is part of why I decided to become a concrete finisher. The thought that the things I pour might be around long after I'm gone, always fascinates me.
The Roman concrete remained known in Italy as "calce idraulica" (hydraulic lime) and was used for underwater structures and impermeabilization of ducts. However brics were preferred for the building of large structures (see for example the dome of Santa Maria del Fiore, in Florence, the first in the world to beat the diameter of the Pantheon) for a simple reason. To produce brics in the immediate proximity of the building, you only need clay and heat, and clay is abundant almost everywere. Not so much for pozzolana and lime, that tend instead to be mutually exclusive, where there is one, there isn't the other.
I was thinking the same thing op. However, historically it seems like the rediscovered this building technology. Also the time period in which it was "lost" was the dark ages, not a lot of economic drive and growth for mega structures as the globe recovered.
@@marcoroberts9462 Concrete can be poured directly underwater. It takes more time to set, but the result is actually stronger. Roman concrete is different from Portland concrete because, while Portland concrete is weakened by salt water, Roman concrete becomes stronger if poured in salt water and, the longer it remains in salt water, the stronger it becomes. That's how the piers of many Roman ports had been made.
Roman concrete is actually what got me into becoming a history buff, I took an engineering class as an elective in high school and our teacher made us watch a documentary on ancient engineering. It was astonishing to learn the techniques and inventions they already had so long ago, and we ended up spending a whole week just learning about concrete with Roman concrete being the start of the lesson. Absolutely crazy stuff, until that class I had never even begun to comprehend the fact that some of these structures are still standing after literal ages of history.
And to think the Romans even knew about pre-stressed concrete: they actually buried tightened chains inside some of the concrete structures which acted like the steel reinforcements we use in modern concrete. Architecture is what got me interested in history initially, and I still find it fascinating.
Roman culture lasted about 800 years. Modern enlightened culture is about 300 years old. And like the Romans western culture is arrogant to an absolute perfect fault. It is the reason why decadences and decay is starting to set in the Western world.
@@bighands69 It's bizarre to see the shell of a vast forum with a stone farm cottage inside it. I wonder if our mighty skyscrapers will one day be aviaries for the simple pleasure of racing pigeons? Hotel rooms on the top floors cheap housing for poor people who have to climb a mile of stairs?
Visiting the Pantheon was easily one of the most mind-blowing experiences an engin-nerd like me could have - walking in through the enormous portico doors, your eyes instinctively drawn upward to the engineering masterpiece of the concrete dome & the oculus flooding the chamber with light.... then remembering that this structure has stood for near 2,000 years.... and it's _completely unreinforced concrete...._ still gives me chills!! 😲💫💜
Yeah, I remember the first time I went. I had seen pictures of it and expected it to be maybe 30-40 meters tall. Then you enter, and look up, up, up until you arch your back backwards and gasp at its beauty, size and age... fantastic building.
Panthéon.. Phi... Same proportion of us.. Hu-mans. Géométries, to let resonate what get a réflécted by/from the Ether. What s been surely avoided to be taught in academy to engine -peers. It s aaaall about Pleroma Platonic Solid Music of the 7 Spheres... Resonances, and fractality. Verbum dei in aeter manebit
A big problem is that the ingredients that made Roman concrete so special (fly ash, salt water, lime) wouldn't be available in other regions, and would have been hard to allocate during periods of conflict and division within areas that these ingredients would be sourced from.
Basically any burnt silica will serve as a pozzolan. The Romans knew they could use crushed pottery or bricks in place of volcanic ash. Ceramics like brick and pottery are made from fired clay. Clay is mostly silica.
Different types of ash can create different types of concrete as can the type of lime that is used in the process. Romans found this out because they experimented and tried new things and it was a market economy that had people trying to find the next big thing.
@@bighands69 yeah, I agree completely. They didn’t have a single mix design. They knew how to make adjustments to their batches based on what they were constructing. Hydraulic concrete vs structural concrete vs decorative, etc. My comment was more of a reflection on why the secrets of Roman concrete were “lost” toward the Middle Ages. The fracturing of the empire and the general state of kingdoms and city states around Europe made for difficult conditions to utilize the mix designs created by the Romans. In most places, it was probably just easier to use mortar and stone.
so the quicklime / lime is found in most europe and was used the whole middle ages. But the volcanic ash was quite rare and also the technic of building with roman concrete is similar or even same as with quicklime. You have to realized roman concrete is a variation of quicklime mortar were you add volcanic ash and other herbs and spices. Now we dont have to wait for volcanic eruption, we can create something similar in cement rotary kiln were slag from steel blast furnace, bricks, sand and herbs and spices were blasted with 1350°C heat melting all the ingrediencies together. The modern concrete started in 1756 natured in 1824 and reached final form in 1849 as reinforce concrete that we use today. Also i think call it roman concrete is kind of wrong, its more like roman volcanic quicklime mortar since is not pored but used as mortar.
Pozzolana is such a good material for concrete because it has immense amounts of small silica strands in it. They prevent cracks from growing as the concrete is being pulled, or in tension. Concrete, like stone, is very strong when it's being pushed on, or in compression. The combination of compressive and tensile strength of the material, plus the way it was bedded in layers, makes Roman concrete one of the best building materials ever developed. In the last century and a half concrete has undergone both a resurgence in popularity and a great deal of technological and material development. The inner secrets of Roman concrete have only become revealed in the last few decades due to our increased understanding of mechanical stresses, due in many ways to aerospace technology, and our better understanding of materials chemistry. There are good Wikipedia articles on this. We're still developing new concrete compositions to match and continue to develop this amazing Roman invention. The amazing technology of their brickwork, such as used so successfully and in such a sophisticated manner in the Hagia Sophia, is also being studied and developed as is their terra cotta technology. We still have a lot to learn from Classical and ancient technology.
Also if I'm not mistaken the Roman written instructions said add water. Romans added sea water people in the future reading the instructions added just water and couldn't figure out why the results were different. It's used as an example of why being clear and precise with your instructions is important.
It blows my mind to think men of today needed to understand technology of today to understand technology of the past. Intuition would have it the other way around. The Romans truly were ahead of their time (and even ours in some ways apparently).
@@AntiquatedApe You have to bear in Mind. These Roman technologies were developed over centuries. Sometimes past down through family generations. This is why there's still some mystery about medieval sword making. (smelting) Imagine having a collective knowledge pass down over a period 2/300 years.. you certainly have learnt all the ways *not* to do something. Plus all the techniques that do work... In Yorkshire there a cisternian abbey called Riveaux Abbey. Was built around 1130. It is said the monks were smelting Iron to make tools 200 years before the industrial revolution...
Those doors are massive! The whole Pantheon experience is mind blowing. I had no idea how enormous the recessed squares around the dome really were!!! It’s not possible to get a good idea of the size and scale of those squares. I wonder how big the squares on the top row are.
The Pantheons dome is just so insanely huge. Photos can say a lot, but nothing beats standing inside the Pantheon, looking up. It's just so massive and you feel soo tiny. It's awe inspiring
I saw reservoires made from 2000 year old roman concrete .. 2000 years under ground and they still look brand new with absolutely no cracks , easily can be mistaken for something modern .. they even filled up with rain water during excavations
I grew up in a small town with alot of Italian immigrants & each of their homes has some sort of unique concrete creation. One yard features a fence with concrete posts & is still my favorite
I have enjoyed every one of your videos, and much enjoyed your book. The Roman and Greek sections of the DIA have long fascinated me (you mention them in your forward), and in fact inspired two of my daughters to study ancient history, one even majoring in the classics and doing quite well in her Latina. Thank you so very much for what you do!
Thank you Dr. Ryan. I’m staying in Rome for the holidays and your videos have inspired many excursions I will take. Already have my ticket for the Domus Aurea… that will be a first for me. Very excited.
The art at 7:28 really puts you in perspective and how eerie it would be to live around this time period. I wonder how these people thought and felt just living day by day surrounded by these magnificent ruins of a past and a people that just disappeared and thinking to themselves what went wrong? Did they feel a sense of regression when looking at these magical-like structures? Or did they just continue on with their lives without much thought about it? What a melancholic time.
I had heard once from a podcast that within only a few generations of the final collapse of Western Rome, many of these people believed the megastructures were built by gods, giants, and other metaphysical forces. It's crazy to think that Nerva's forum was probably built 400-500 years before this period, which is a longer time than the United States has even been a country.
Its kind of the reason for the incredibly widespread trope of knowledgeable ancients that has permeated collective consciousness. From sci-fi with ancient aliens building megastructures and disappearing, to fantasy and the elves accomplishing great things in golden ages that the modern people can't comprehend, the trope is everywhere. Even the phrase "they don't make em like they used to" can possibly be ascribed to this idea that they built things better in the past, even if we're more advanced than ever in the present.
@@TheRaptorsClaw we r not more advanced than ever in present... Jahjahjah. It s the opposite dude. Pls, get aware. Embarassing ignorance... As more we go on, as further we get from real tech. Once upon a time with sound all was doable. Now is hoax techq. Wake up please. It s for ur own culture 😁🙏
It wasn't really forgotten. The Roman concrete remained known in Italy as "calce idraulica" (hydraulic lime) and was used for underwater structures and impermeabilization of ducts. However brics were preferred for the building of large structures (see for example the dome of Santa Maria del Fiore, in Florence, the first in the world to beat the diameter of the Pantheon) for a simple reason. To produce brics in the immediate proximity of the building, you only need clay and heat, and clay is abundant almost everywere. Not so much for pozzolana and lime, the components of Roman concrete, that tend instead to be mutually exclusive, where there is one, there isn't the other.
I've often wondered why the Roman constructions of concrete weren't more widely copied around Europe, and why the use of it disappeared. Thank you for a very clear explanation.
Thank you for including the photo of the Pantheon dome with people for scale. I never realized how large and how high up the square features in the dome are.
Videos like this are why yours has quickly become my favorite history channel. I'd often wondered about this very subject, but never came across an answer.
Great job getting a sponsor! I'm so glad to see people like you who are making quality and interesting educational content succeed. You deserve it!!!!!!
I LOVE this channel. You put good research together with great photos, interesting facts and commentary. This is definitely your calling and I'm sure this channel will grow.
Modern aggregate tends to be of uniform size, small pebbles mixed in to give it strength. At the Colosseum, I saw in a broken column that the agregate was rocks, broken bricks, and whatever they found lying around.
@@robertbolstad9465 Marcus Vitruvius Pollio author of "De architectura", under the patronage of Augustus - not a slave; Apollodorus of Damascus. favorite of emperor Trajan, designed the famous Column (which still stands) and Forum of Trajan, and also apparently the Pantheon in the video - not a slave; Sextus Julius Frontinus, held high public offices under Domitian, was born of equestrian rank, and reached senatorial rank later in life (the most powerful elite of Rome aside for the emperors) - obviously not a slave. A lot of public construction work was done by the roman military: each legion had a chief architect/engineer responsible of the construction work the "praefectus fabrum", also responsible for the construction of military engineering works like artillery machines and camps/fortification - this a was a prestigious position definitely not held by slaves. What kind of bs are you trying to peddle and for what purpose I wonder?
Great stuff. In short: i) Roman concrete (as a cheap construction material) was not widely used outside of Italy, ii) in large-scale Post-Roman structure's of Germanic and Greek traditions of building, concrete was largely irrelevant, and iii) it wasn't so much intellectually forgotten* as of little practical use, e.g. where stone, brick, or timber offered local, relatively cheap, and more or less durable alternatives to concrete blocks (i.e. for most places outside of Italy). ;o) * Mortar as a concrete binding was a well known and increasingly widely used material, not least in Northern Europe, as more suited to the newer styles of building (cathedrals, castles, etc).
It wasn’t used outside the peninsula after the sack of Rome. Before then, buildings were constructed in the vain of Roman architecture with concrete. After the sack of Rome, where it lost power and influence and probably financial resources, it might have seemed irrational to overcapitalise on construction. Constantine gained influence in the Middle East after the sack of Rome and Christian architecture dominated as a form of public building. Serfdom was invented and the Byzantine Empire flourished. Possibly also people weren’t living as long and population growth was negative. Manual resources were not as readily available as it once was during reign of capital Rome.
"Mortar" is not one particular material. The Romans used hydraulic cement for mortar, which is the same glue that holds together Roman concrete. The Ziggurat of Ur uses bitumen (i.e. tar or asphalt) as a mortar. The Egyptians often used clay. During the Middle Ages (and really until the discovery of Portland Cement), Western Europe used non-hydraulic lime mortar; aka slaked lime. Even if you're building a structure out of stone or brick, hydraulic cement (which is the essential ingredient of Roman concrete) is considerably advantageous to slaked lime mortar. Slaked lime mortar takes days to cure (if it ever cures at all in thick walls). It sets by absorbing carbon dioxide, so it must be exposed to air. It isn't nearly as strong as hydraulic cement, nor does it adhere very well to stone or brick. Simple recipes for hydraulic mortar persisted in the East throughout the Middle Ages. When the Byzantines spread their knowledge to the Kievan Rus, they taught them how to make hydraulic mortar with lime and crushed pottery. If Western Europeans knew how to make hydraulic cement, they almost certainly would have used it over slaked lime. Both hydraulic cement and slaked lime start out the same way- limestone must be quarried and baked. The next part is simply whether pozzolans like volcanic ash or crushed brick are added. That changes the chemistry and how it cures.
" it wasn't so much intellectually forgotten" a long time ago as a history student I was shown a bit of medieval XIIth century mortar from before the Mongol invasion and it was harder than modern concrete (could not mark it with iron), and I was told told that's how I was supposed to date buildings older than 1241 ... it was not forgotten but as you say it was too expensive when good stone was available we imagine that the Romans were like superengineers, but my guess is they did not really know what they were doing and we see only the happy accidents that survived while they built mostly of wood and rough cut stone and all the less happy accidents were mined for stone since then outside the core of the Roman Empire there were more buildings constructed during the Middle Ages than during Antiquity ... also more written sources: what do we have that was written in Gaul or in Britannia from the Roman time ? All was about Rome or Constantinople, but as soon as the "barbarian" auxiliaries take over writers appear and are still preserved like almost everywhere including across the former borders of the empire
@@Ntyler01mil slaked lime mortar can be more elastic which could be useful with an expansive clay substrate of sudan for example vs natural limestone hills
Thank you for creating this. This video poses a question that's always puzzled me since seeing the Pantheon and reading "Brunelleschi's Dome." But I'm not yet convinced by this video's thesis that concrete was just no longer needed.
Very interesting video as always! Interesting because I never realised that the Roman concrete was relatively little used outside Italy around the empire. I didn't know also that the Church of Hagia Sophia was not made of Roman concrete but bricks! Of course with the decline of the Roman empire the Roman concrete was not required anymore and the Basilica was made of bricks. Thanks for sharing this very informative video 👍👍
@@dfirth224 wrong, the church used everything that is Roman including "recycling". What the church refused to do was building a pagan temple especially since the proclamation of the Edict of Milan in 313, which declared tolerance for Christianity.
@@dfirth224 The church is Roman. Medieval Europe was a totally Romanized society, from clothes, to customs, to language, to religion. The Roman empire itself was still around during the middle ages.
The Hagia Sophia does actually use Roman Concrete, as did many other structures in Constantinople, but the Romans also used bricks quite prolifically throughout the period of the empire. Hagia Sophia was actually built to be fireproof through some ingenious methods.
Perhaps it was done to make people not feel lost inside that giant dome? Makes it look more to human scale, the roof, one would think, is not that high above your head. Sort of the exact opposite of all buildings in Disney World, that appear to be bigger than they really are.
Unfortunately, "While it is unclear when concrete originated, it is likely that attempts to make it occurred at several locations during the Neolithic period. Some of the oldest known examples include lime concrete floors at Yiftahel, southern Galilee, from around 7000 BCE, and Lepenski Vir, Serbia, around 5600 BCE.
There is a nice article in Wikipedia on Roman concrete The Pozzolanic Ash is the ingredient that makes Roman concrete unique. The Pozzolanic Ash comes from the volcanic fields around Naples, the Vesuvius area, and it apparently has a very rare chemistry. It was great luck that this rare ash fell into the hands of the Romans. Salt destroys todays modern concrete, so there is an effort to use a concrete similar to Roman concrete in areas effected by salt. Even in areas not near the sea, modern concrete has been destroyed by using salt, such as, on icy concrete bridges here salt is used to melt the ice. - Thanks for the discussion on how Roman concrete was placed. The use of a very dry mix was the key, as modern concrete is quite wet and flows like mud and would destroy the brick forms.(1:05)
@@BotanyDegreePilkerton Do you people not understand how to use wikipedia? After each claim, there will be a small number in brackets next to the sentence. At the bottom of the page, you find the source material for the claim. Those links are what should be used.
I'm, I will disagree to your saying that they could not calculate forces and tensions mathematically.It stupid to consider that they've built two enormous hippodrome just because the concrete was good.they had very good knowledge of forces stresses etc.In Spain they made a pool on top of a mountain and a tunel from the top to then center of the mountain, then they let the pool water flow in the tunel in the mountain, the potential energy became kinetic energy and all of it had no way to release but by breaking the mountain apart, thing is that they succeed it, so they knew how much water to add to do the job, the mountain had valuable minerals for the empire...I have a book on the hellenistic science and I can assure you that they were incredibly familiar with classic physics in the level we are today, they just had no formulas and so it was quite hard to pass this knowledge without studying a lifetime.They knew the 1st law of Newton by the meaning and not by the formula ΣF=ma.So yeah they knew very well what they were doing that's why their buildings still stand.
They could not calculate those things mathematically. You said it yourself "they didn't know the formulae". Moreover, you look at the pantheon now and think that they had to know exactly what they were doing, but that dome actually collapsed several times, and the one we have now is just the longer lasting one. Romans were builders but not mathematicians. Things stayed up because that time they did, not because they calculated it properly
@@giovanniriccardovigano3990 The Pantheon's dome never collapsed. It cracked and was rebuilt all through its history. The dome of Hagia Sophia collapsed I think 3 times. It was always rebuilt.
@@giovanniriccardovigano3990 omg...omg dude you have zero idea of the level of the mathematics of the period, just zero.The fact that they had no formulas doesn't mean that the people who knew how physics, weren't able to calculate.You want to tell me now that Diophantus wasn't able calculate(? ), he knew better mathematics than me and im physicist.They've built hydraulic robots,the book was know up to the middle ages, the muslim world attempted to make some of inferior quality and they succeed, the byzantines had a bunch of them in Constantinople to impress the barbarians, you want to tell me that they calculated the stress and the forces of the gas by mistake, or by guessing?
@@giovanniriccardovigano3990 considering the Antikythera Mechanism it would be weird to think the ancient world didn't have advanced abilities in mathematics and physics. It just wouldn't have been possible to build a machine like that without this kind of knowledge.
The reason many of these ancient structures remain erect is not the result of Newtonian physics, regardless of whether they had formulas or not. There WAS a knowledge and incorporation of sacred geometry. The utilization of the Fibonacci sequence, as an example. That is not something that necessarily needs formulas, but can be drawn out while creating blueprints/design, and it can be represented mathematically as well. This knowledge was used not only to make something be viewed as aesthetically pleasing, or even correct from some perspectives, but it was used to consider how the forces of nature would impact the durability of the structure. While we have to build strong foundations, incorporate steel in the framing, or come right back to retrofit a building to achieve a higher degree of confidence it won't crumble, the ancient architects needed none of that. Newtonian physics are not why these buildings last.
Well done video! At 1:33 you show an old photo of a crack in the dome of the Pantheon. Is it common for this to happen? Does the Pantheon require a lot of maintenance? How would a crack like this be repaired? Would it be repaired using the original Roman concrete or something different? Thanks
@@ianchandley - It is important to understand the chemistry. Roman concrete is hydraulic cement plus an n aggregate. Hydraulic cement wasn't used at all in Western Europe throughout the Middle Ages. They settled for slaked lime mortars. Hydraulic cement would be advantageous in many circumstances, so it's hard to argue they still knew the recipe but didn't bother to ever use it.
@@ianchandley simply "burning limestone" produces lime...the Roman innovation was incorporating natural pozzolans, which are a product of vulcanism. Modern concrete uses synthetic pozzolans...Portland cement,, fly ash, silica fume. Lime is part of the recipe, but mostly to increase the alkalinity of the mixture (which activates the pozzolans).
My thoughts on why Concrete slowly phased out could also be from a lack of the fine volcanic powder due to overuse as well. But, I also dont know the volcanic activity too well without more info.
Here’s a strange compliment: Your speech patterns in reading remind me of Lt. Cmdr. Data on Star Trek. Or you could play a great Vulcan. Your diction is perfect. Your content is absolutely superb, btw. Subscribed!
Producing baked lime in large quantities would have been an ordeal after the collapse of Roman resource management. If you can't produce enough concrete to pour a cathedral, you can still produce enough concrete to cement blocks of stone into an aggregate structural support. It takes a lot of wood to build a colosium, and first you have to mine and mill the limestone. The architecture of the medieval period in Europe is still pretty impressive, given that cement in an age without mass-production, was using concrete in mortar to glue together the building blocks of gothic cathedrals.
You are assuming that there was no "mass production"...Check out the perfect 10.000 year old statues found throughout India....produced mathematically perfect...by some kind of forgotten tech.
Actually, it's horrible. His mis-pronunciation of "concrete" is a distracting affectation. What is amusing is that he doesn't do it consistently which shows it really is a deliberate affectation. To be fair, I've heard much worse.
The simple fact that making good concrete was a precise and somewhat difficult process impeded its use. The ratios had to be very close and the materials not always easy to find. These difficulties combined with a loss of nearly everything related to advancement in culture must have contributed to the decline in concrete. Similarly, the Greeks also lost the ability to turn the drums needed for fine fluted, tapered marble columns and this skilled art did not return to Greece until modern times, much later than concrete.
Great video. I just have one different thought about the end. I don't think concrete was irrelevant in the Middle Ages. It's 100% necessary for many things that would have improved their lives, such as clean water fountains, interior running water, pipes, radiant heat, steam rooms to bend wood for ship/furniture making, sewer systems, paving roads, building bridges, etc. (Remember, sets underwater?) But, like any other trade - it's a skill. One that can be quickly lost if a mere two generations go by without practice. Barbarians killing people who had skills they didn't need likely explains it. And general instability/starvation. Recipe books are one thing, constructing a safe structure is another. That takes learning from masters. People likely got scared by failed revival attempts, and lost faith. Without concrete, there was a decline in cleanliness and bathing, an increase in plagues, a near stoppage of bridge building, harbors couldn't be rebuilt after storms/quakes, floors for the average citizen became mud, (easily dug into by rodents,) and underground water storage became a pipe dream for your new community. Concrete, just one of many techs that could have improved their lives if not forgotten. Making pipes, grading sewers, reservoirs and drainage tunnels, wells, and so importantly, paved roads...really really could have helped people. Especially after the invention of the horseshoe, which means horses didn't have to be put to death early if they wore down their hooves on hard surfaces. How many famines could have been averted if harvests never failed to be transported because of deep mud? The need for it was there, just sadly, it was lost.
@@bighands69 That's just not true, because concrete and mortar was used all over Europe during the middle ages, and specifically Roman Concrete was used in Italy, and in the eastern half of the empire throughout the period. "Dark Ages" is a pop history term. It's not a thing for actual historians except for specific regions at specific times where no sources have been preserved, like 5th century Britain. There was no "collapse of civilization" on mainland Europe, and main written sources survive.
@@bighands69 "The dark ages" was a pejorative used by protestant and later enlightenment polemicists. If an historian uses the term, they're referring to something specific, like "the Greek Dark ages" from 1200-900bc, or "Dark Age Britain" roughly from 400-600ad. There's no sources, so it's dark, like we can't get a picture of life during that time. They don't use the phrase for medieval Europe. There's late antiquity (250/300 to 600/700). There's the early middle ages(roughly 500-1000), the high middle ages (roughly 1000-1250), and the late middle ages(1250-1500). The "Italian Renaissance" is during the late middle ages. Mainland Europe is full of sources. There's more people writing in the 6th century than there was in the 2nd century when Rome was at its height. There's no such thing as some sudden collapse of culture, or civilization, or even the Roman empire itself, which ruled the Mediterranean until about 650-700, then waxed and waned for another 7 centuries.
@@histguy101 No it is not just a made up term. It literally means there was a period of darkness. Very little is known of that period and very little remains. It is ironic that lots of roman architecture exists but very little exists of the dark age. It has even been noted that Roman Architecture in Britain is of a certain quality and when the Roman empire collapses there is a decline in quality. As there was a dark age it is not even understood how Rome actually fell. There are many theories but little understanding or evidence.
Pretty good work there. You might have noted how the technique, of pounding or vibrating a small ratio of water throughout the mix, is now being used in dam construction.
If you are interested/curious about buildings, architecture, construction, history,....go see the Pantheon. Inside it and outside. I've been there many times and it always blows my mind. You will be in awe. The dome looks surreal at times. Literally as if it is painted on. But if you take a very close look at 0.10 or at 3.20, you will notice that there are no paintings on the higher part. It is all concrete structure. And nearly 2000 years old. Incredible.
The romans utilized concrete rather than wood in and around Rome due to the lack of available tree's that one needs to provide lumber. When Rome ventured north in to Europe, the abundence of tree's allowed them to and they did utilize wood rather than concrete. Using wood which was more available in Europe vs the area's around Rome was considerably a faster more proficent process then the use of concrete.
The Romans still used a lot of wood. Many Roman apartment buildings were built with "opus craticium," which consisted of a timber frame skeleton with panels of wattle & daub (wicker frames covered in mud, essentially), mud brick, or other masonry. This type of construction was a big reason for why fires were so common in ancient Rome. Vitruvius complained about the construction method for how easily it burnt down, along with its susceptibility to moisture and decay. This means that much of Ancient Rome likely had an appearance that would be more readily associated with medieval London or Paris. Even when buildings had masonry outer walls, wood was typically used for floors, roofs beams and internal partitions. Long after Nero's building reforms following the Great Fire of 64, it appears that wood was still the principle construction material for many buildings. For instance, Herodian of Antioch tells us that the Praetorian Guard responded to urban unrest in 238 by burning down the apartment houses from which hoodlums were launching projectiles, adding that "great number of houses were made chiefly of wood.” Timber frame buildings do have some advantages as well. They can be more earthquake resistant, and Vitruvius tells us that they were much more economical and faster to build. Vitruvius also tells us that the walls of such buildings were thinner, leaving more useable space.
Sadly, I have heard they also completely obliterated the woodlands of the north in places like Ireland and Scotland where so few trees remain today. The Irish and Scottish, too had a special relationship with nature, and even though attempts have been made, they have never been able to restore the land as it had previously been. Fortunately there is enough moisture there that the land would not be at risk of desertification as some areas of North Africa and the Middle East, but I find it pretty sad to know just how much the Romans destroyed around the world, and that earth still suffers from their selfish, power hungry, and destructive actions today.
I would posit one more explanation: experience, or lack thereof It is one thing to have access to the recipe and general description of how to use it, but another thing entirely to actually know how to use it. It took roman architects and builders centuries to develop and refine their understanding of the material. Once this practical knowledge was lost there was just no way of getting it back, since it would by necessity have been transmitted through non-literary means. Thus, once demand declined, there would be fewer opportunities to train new masons, which would make it harder to comission new concrete buildings because the expertise would be harder to find, creating a vicious cycle.
The more I hear about the things forgotten during the Middle Ages, the more it saddens me. If the internet had been invented 2,000 years ago, imagine where humanity would be now. Imagine what we'd remember.
Another excellent topic would be the overall decrease of Roman art into the child-like art of the Middle Ages. Or as my wife has stated so many times ‘they lost perspective’ ba-dum-tish’
Many thanks for taking the trouble to share this with us. I think the National Geographic did an article on the Port of Caesar-ea. I think about 800 large ship loads were imported of pozzolana because they did not trust the local material. Caesar-ea is pronounced with a 'C', and not a 'K' as in Kaiser.
I'm not sure the romans were tied to any set way of doing things in terms of materials. If it was more practical to use local "ingredients" then that would often be the case. Something designed for an emperor is obviously only going to use the best and that probably means imported from Italy. For most of the rest of the population if you already have ample supplies of water, chalk, gravel, sand, pumicite etc etc then all you really need is someone with a good knowledge of the process. I think the question remains mostly unanswered. The finer points of moulding and sculpting might have more to do with it's disuse.
Fascinating video, seriously!!! I didn't know that a harbor had been built of concrete as late as the 6th century AD ! The part it dosen't explain though is why didn't they use concrete again during the renaissance. You would think that logically it must have been forgotten by then
Years ago, I was making railings for the front steps of a church in Kendal for English Heritage, when I heard the architect, (she would have been in her Thirties) tell the gnarly old Irish foreman, "No! It HAS to be goat´s hair mortar, horse hair simply WILL NOT DO." And she was right. These things matter. I set the railings into the stone with hot lead, I think I was the only person they could find who still did that, and they were careful not to ask if I had any insurance for the process. Houses have a design life of less than fifty years now, concrete? Huh! You could probably use bloody marzipan.
Every time I see depictions of middle age life in Rome I think how wild it is to see people dwelling amongst and within these titanic ruins. A millennia old city of a million reduced to 20,000 over the course of a few centuries. And then I think of Detroit.
Thanks, this was enlightening. no mention though of shuttering, formwork, also no reinforcement was used, how was that avoided? Concrete is, apparently the 2nd most widely used substance after water & the third largest carbon dioxide emitter in the world
Roman concrete walls were almost always faced with a course of brick, which served as shuttering. For domes like the Pantheon's, huge wooden frameworks were constructed. Although primitive rebar was very occasionally used (iron bars were sometimes set into angles), the Romans generally assumed that their concrete was stable enough to need no reinforcement. Remarkably - at least in some cases - they were right.
It would be fantastic if you could link or refer to the sources you used for this video. I'm interested in checking by myself and having my own conclusions. I think it'd give this channel a more serious, professional way of explaining history :) Otherwise, we can't know if the information of the video is real and accurate or not
Saw another Roman Concrete video that says the recipe using specific ingredients caused a change at the molecular level and actually gets harder the longer it is exposed to seawater. Amazing Stuff!!
During the Renaissance, scholars and artists wrote essays and poems contemplating the wonders of the ancient city. But we know frustratingly little about what Rome's medieval inhabitants thought, since only a few travelogues survive.
01:30 The concrete used on the pantheon, is not structural, it is a veneer. Look at the crack. The structure is made of brick, and just covered in concrete to give it a "finished" look, without having to take a ton of time making sure all the exposed brick cuts needed and joints were uniform, laid uniform, and appealing to the eye. Even though it would look WAY more impressive had they not veneered it in concrete. The outside is all exposed brick, except for the north side, which is hidden behind stone. It has been changed so many times through out history, do we even know if the concrete veneer was even on the dome ceiling originally, or if it was added later, as a band-aid?
@@Ntyler01mil Really?, When i was there in Sept, it was all brick. Might want to take a look yourself. Im also a mason, who is a member of the union that was hired to figure out how Duomo in Florence was built, since no one in Italy knew. Cool NatGeo episode about it.
@Detonate Klubstompers Oh my god, you're right! 😃 ...So all this talk about "The largest unreinforced concrete dome in the world," is about what, exactly? Lol! Are you, and the people in this picture, the only people who knows this! 😂
@@klubstompers In the diagram in the vid, they used a brick wall as a "form" when laying the concrete, and left it in as part of the structure. Perhaps that is what you are seeing.
Dear Garrett, What is the source of the final image of the Forum of Nerva? I've seen that and two or three other similar images a couple of times on the internet and would love to buy the publication it's from. Many a Google session has only yielded one small Italian PDF file on the Roman Imperial Fora. Would love to find the source!
I’m partner in a company that 3D prints houses out of concrete. We are now in R&D with geopolymers similar to the what the Romans discovered in the chemical reaction & tetrahedral bond occurring between silica & alkali. It can last thousands of years, is bulletproof, and heat resistant even at 3000 F. New evidence is pointing at the Pyramids of Giza also being geopolymer. Really fascinating stuff. Thanks for the video!
It's fascinating that the concrete in the Pantheon is still curing and getting stronger every day even now. It's my belief that the Egyptians had a form of concrete even much earlier than the Romans or more precisely, before there was a Roman Empire, and used it to build most of the great pyramids at Giza, aside from the very few granite blocks that were used in some of the Interior spaces. The crude concrete mix used by the Egyptians would be, and is, almost indistinguishable from natural limestone. We tend to think of concrete as the modern concrete which is very uniform in its ingredients so that there's little difference between concrete in China and concrete in the US or Europe. This can close our minds to the possibilities of its existence in different forms in the distant past. The idea that the ancient Egyptians used their own type of concrete makes the building of the pyramids a still phenomenal feat of engineering but, also a doable one as well.
![[4K] Watch SpaceX Catch A Starship Rocket From Space!!! #IFT5](http://i.ytimg.com/vi/pIKI7y3DTXk/mqdefault.jpg)
My interest in Ancient Rome is part of why I decided to become a concrete finisher.
The thought that the things I pour might be around long after I'm gone, always fascinates me.
Follow your dreams chief, I respect it.
@@protendi I have a degree in construction and I am a CGC in Florida. The Pantheon intimidated the hell out of me!
I drive a mixer
Thanks. I run a company now and we make sure everything is built to last. Maybe not as long as Roman concrete but we do try
Nice!
The Roman concrete remained known in Italy as "calce idraulica" (hydraulic lime) and was used for underwater structures and impermeabilization of ducts. However brics were preferred for the building of large structures (see for example the dome of Santa Maria del Fiore, in Florence, the first in the world to beat the diameter of the Pantheon) for a simple reason. To produce brics in the immediate proximity of the building, you only need clay and heat, and clay is abundant almost everywere. Not so much for pozzolana and lime, that tend instead to be mutually exclusive, where there is one, there isn't the other.
🤦♂️🤣 yea okay. Have you ever built under water?
@@UnseenEternalStudios not built underwater, built outside of water and placed into water 🤦♂️
@@UnseenEternalStudios why don't you have under water building skills? Did you go to a public school or state college?
I was thinking the same thing op. However, historically it seems like the rediscovered this building technology. Also the time period in which it was "lost" was the dark ages, not a lot of economic drive and growth for mega structures as the globe recovered.
@@marcoroberts9462 Concrete can be poured directly underwater. It takes more time to set, but the result is actually stronger.
Roman concrete is different from Portland concrete because, while Portland concrete is weakened by salt water, Roman concrete becomes stronger if poured in salt water and, the longer it remains in salt water, the stronger it becomes. That's how the piers of many Roman ports had been made.
The scale of the Pantheon's dome was not fully impressed upon me until I saw that photo featuring the crack.
I've walked inside the Pantheon many years ago on a schooltrip and it never occurred to me those 'tiles' were so massive in size.
So true!
Same! Phenomenal!
Absolutely. That really made me do a double take!
Ya that had me in a bit of shock there lol
No annoying music, no chitty chat , straight to the point , eloquently and coherently spoken, very informative, wonderful video
Roman concrete is actually what got me into becoming a history buff, I took an engineering class as an elective in high school and our teacher made us watch a documentary on ancient engineering. It was astonishing to learn the techniques and inventions they already had so long ago, and we ended up spending a whole week just learning about concrete with Roman concrete being the start of the lesson. Absolutely crazy stuff, until that class I had never even begun to comprehend the fact that some of these structures are still standing after literal ages of history.
And to think the Romans even knew about pre-stressed concrete: they actually buried tightened chains inside some of the concrete structures which acted like the steel reinforcements we use in modern concrete. Architecture is what got me interested in history initially, and I still find it fascinating.
Funny it made me wanna be an engineer. Almost got my bachelor's
Art History.. Roman Concrete was Discussed..No kidding..
Roman culture lasted about 800 years. Modern enlightened culture is about 300 years old. And like the Romans western culture is arrogant to an absolute perfect fault. It is the reason why decadences and decay is starting to set in the Western world.
@@bighands69 It's bizarre to see the shell of a vast forum with a stone farm cottage inside it. I wonder if our mighty skyscrapers will one day be aviaries for the simple pleasure of racing pigeons? Hotel rooms on the top floors cheap housing for poor people who have to climb a mile of stairs?
Visiting the Pantheon was easily one of the most mind-blowing experiences an engin-nerd like me could have - walking in through the enormous portico doors, your eyes instinctively drawn upward to the engineering masterpiece of the concrete dome & the oculus flooding the chamber with light.... then remembering that this structure has stood for near 2,000 years.... and it's _completely unreinforced concrete...._ still gives me chills!! 😲💫💜
Yeah, I remember the first time I went. I had seen pictures of it and expected it to be maybe 30-40 meters tall. Then you enter, and look up, up, up until you arch your back backwards and gasp at its beauty, size and age... fantastic building.
You are so right, I still get chills as I remember gazing up at the oculus over 3 decades ago absolutely thrilling!
Panthéon.. Phi... Same proportion of us.. Hu-mans.
Géométries, to let resonate what get a réflécted by/from the Ether. What s been surely avoided to be taught in academy to
engine -peers.
It s aaaall about
Pleroma
Platonic Solid
Music of the 7 Spheres...
Resonances, and fractality.
Verbum dei in aeter manebit
@Seven Inches of Throbbing Pink Jesus 🙏😎🍻
@Ivan no more battery... On the mountain. I can fload you with deep inputs about whatever u need brother
A big problem is that the ingredients that made Roman concrete so special (fly ash, salt water, lime) wouldn't be available in other regions, and would have been hard to allocate during periods of conflict and division within areas that these ingredients would be sourced from.
Basically any burnt silica will serve as a pozzolan. The Romans knew they could use crushed pottery or bricks in place of volcanic ash. Ceramics like brick and pottery are made from fired clay. Clay is mostly silica.
Different types of ash can create different types of concrete as can the type of lime that is used in the process.
Romans found this out because they experimented and tried new things and it was a market economy that had people trying to find the next big thing.
@@bighands69 yeah, I agree completely. They didn’t have a single mix design. They knew how to make adjustments to their batches based on what they were constructing. Hydraulic concrete vs structural concrete vs decorative, etc.
My comment was more of a reflection on why the secrets of Roman concrete were “lost” toward the Middle Ages. The fracturing of the empire and the general state of kingdoms and city states around Europe made for difficult conditions to utilize the mix designs created by the Romans. In most places, it was probably just easier to use mortar and stone.
so the quicklime / lime is found in most europe and was used the whole middle ages. But the volcanic ash was quite rare and also the technic of building with roman concrete is similar or even same as with quicklime. You have to realized roman concrete is a variation of quicklime mortar were you add volcanic ash and other herbs and spices. Now we dont have to wait for volcanic eruption, we can create something similar in cement rotary kiln were slag from steel blast furnace, bricks, sand and herbs and spices were blasted with 1350°C heat melting all the ingrediencies together. The modern concrete started in 1756 natured in 1824 and reached final form in 1849 as reinforce concrete that we use today. Also i think call it roman concrete is kind of wrong, its more like roman volcanic quicklime mortar since is not pored but used as mortar.
Also, lime is everywhere. It's just baked limestone. Virtually every medieval building throughout Europe uses slaked lime mortar.
Pozzolana is such a good material for concrete because it has immense amounts of small silica strands in it. They prevent cracks from growing as the concrete is being pulled, or in tension. Concrete, like stone, is very strong when it's being pushed on, or in compression. The combination of compressive and tensile strength of the material, plus the way it was bedded in layers, makes Roman concrete one of the best building materials ever developed. In the last century and a half concrete has undergone both a resurgence in popularity and a great deal of technological and material development. The inner secrets of Roman concrete have only become revealed in the last few decades due to our increased understanding of mechanical stresses, due in many ways to aerospace technology, and our better understanding of materials chemistry. There are good Wikipedia articles on this. We're still developing new concrete compositions to match and continue to develop this amazing Roman invention.
The amazing technology of their brickwork, such as used so successfully and in such a sophisticated manner in the Hagia Sophia, is also being studied and developed as is their terra cotta technology. We still have a lot to learn from Classical and ancient technology.
Yo if you're into masonry, check out the fuckin gaustovino arches
What he said
Also if I'm not mistaken the Roman written instructions said add water. Romans added sea water people in the future reading the instructions added just water and couldn't figure out why the results were different. It's used as an example of why being clear and precise with your instructions is important.
It blows my mind to think men of today needed to understand technology of today to understand technology of the past. Intuition would have it the other way around. The Romans truly were ahead of their time (and even ours in some ways apparently).
@@AntiquatedApe
You have to bear in Mind.
These Roman technologies were developed over centuries. Sometimes past down through family generations.
This is why there's still some mystery about medieval sword making. (smelting)
Imagine having a collective knowledge pass down over a period 2/300 years..
you certainly have learnt all the ways *not* to do something.
Plus all the techniques that do work...
In Yorkshire there a cisternian abbey called Riveaux Abbey.
Was built around 1130.
It is said the monks were smelting Iron to make tools 200 years before the industrial revolution...
The Pantheon, is the size of half football field, even fifty years after seeing it, it's awesome in my mind.
Doors, also a serious engineering marvel!
How old are you
@@PriyankaSingh-jw9ug atleast 51 years old
Those doors are massive! The whole Pantheon experience is mind blowing. I had no idea how enormous the recessed squares around the dome really were!!! It’s not possible to get a good idea of the size and scale of those squares. I wonder how big the squares on the top row are.
I randomly thought of this question one day. I was interested why they forget about concrete. This video really helped. Thanks!
I have to say your style of narration is wonderful for me. Using pauses helps greatly for me to follow along with the information.
I love how you cover things that other channels would never pay attention to. Thanks!
The Pantheons dome is just so insanely huge. Photos can say a lot, but nothing beats standing inside the Pantheon, looking up. It's just so massive and you feel soo tiny. It's awe inspiring
I saw reservoires made from 2000 year old roman concrete .. 2000 years under ground and they still look brand new with absolutely no cracks , easily can be mistaken for something modern .. they even filled up with rain water during excavations
hempcrete was used then as well, lesser discussed topic
It's not the water that causes cracks, it's ice. Since it's hardly ever freezing in Rome, there are not many damages.
@@holger_p having no rebar means no oxide jacking to force it apart from within.
Every video is so well done an just looking at the pictures alone on pause i find myself imagining those times ..great stuff thanks.
I grew up in a small town with alot of Italian immigrants & each of their homes has some sort of unique concrete creation. One yard features a fence with concrete posts & is still my favorite
Clicking the bell
Your content is the exact sort of stuff I've freaking always wanted
PLEASE never stop making stuff, I appreciate you so much
I have enjoyed every one of your videos, and much enjoyed your book. The Roman and Greek sections of the DIA have long fascinated me (you mention them in your forward), and in fact inspired two of my daughters to study ancient history, one even majoring in the classics and doing quite well in her Latina. Thank you so very much for what you do!
"Chemistry they knew nothing about"
*Romans doing that chemistry in the finest way possible
My sentiments exactly.
Forget the middle ages, the secret ingredient of Roman concrete - aluminium tobermorite in volcanic ash was only discovered in 2017.
Trial & Error over centuries...?
@@catinthehat906 I didn't know that at all, neat!
Absolutely.
Another unique and great topic! Thanks for another great upload bud!
I just finished your book. Excellent! Informative and extremely entertaining. Thanks for researching and writing it!
Thank you Dr. Ryan. I’m staying in Rome for the holidays and your videos have inspired many excursions I will take. Already have my ticket for the Domus Aurea… that will be a first for me. Very excited.
How exciting for you!!
Briskly-paced and informative. Many fine illustrations underscore the points.
The art at 7:28 really puts you in perspective and how eerie it would be to live around this time period. I wonder how these people thought and felt just living day by day surrounded by these magnificent ruins of a past and a people that just disappeared and thinking to themselves what went wrong? Did they feel a sense of regression when looking at these magical-like structures? Or did they just continue on with their lives without much thought about it? What a melancholic time.
I would love to learn more about late antiquity/early middle ages on a generation to generation scale for this very reason... if it were possible
I had heard once from a podcast that within only a few generations of the final collapse of Western Rome, many of these people believed the megastructures were built by gods, giants, and other metaphysical forces. It's crazy to think that Nerva's forum was probably built 400-500 years before this period, which is a longer time than the United States has even been a country.
Agree with all of you. I always think these very same thoughts, about the people living amongst the ruins. It’s bonkers to me.
Its kind of the reason for the incredibly widespread trope of knowledgeable ancients that has permeated collective consciousness. From sci-fi with ancient aliens building megastructures and disappearing, to fantasy and the elves accomplishing great things in golden ages that the modern people can't comprehend, the trope is everywhere. Even the phrase "they don't make em like they used to" can possibly be ascribed to this idea that they built things better in the past, even if we're more advanced than ever in the present.
@@TheRaptorsClaw we r not more advanced than ever in present... Jahjahjah. It s the opposite dude.
Pls, get aware.
Embarassing ignorance...
As more we go on, as further we get from real tech. Once upon a time with sound all was doable.
Now is hoax techq. Wake up please.
It s for ur own culture 😁🙏
That was outstanding! I talk about this in my class, but never knew why it was "forgotten ". Truly a case of occams razor viv a vis this subject.
It wasn't really forgotten. The Roman concrete remained known in Italy as "calce idraulica" (hydraulic lime) and was used for underwater structures and impermeabilization of ducts. However brics were preferred for the building of large structures (see for example the dome of Santa Maria del Fiore, in Florence, the first in the world to beat the diameter of the Pantheon) for a simple reason. To produce brics in the immediate proximity of the building, you only need clay and heat, and clay is abundant almost everywere. Not so much for pozzolana and lime, the components of Roman concrete, that tend instead to be mutually exclusive, where there is one, there isn't the other.
I've often wondered why the Roman constructions of concrete weren't more widely copied around Europe, and why the use of it disappeared. Thank you for a very clear explanation.
Thank you for including the photo of the Pantheon dome with people for scale. I never realized how large and how high up the square features in the dome are.
I appreciate your efforts and enjoy the lack of hype and bravo opinion so popular in RUclipss these days. I will go order up your book today!
Videos like this are why yours has quickly become my favorite history channel. I'd often wondered about this very subject, but never came across an answer.
I second that
I'm literally obsessed with Roman Concrete, i think about it every time I see a crumbling ferroconcrete facade
I dream about Roman concrete.
Great job getting a sponsor! I'm so glad to see people like you who are making quality and interesting educational content succeed. You deserve it!!!!!!
A fascinating report and informational video on Roman concrete!! Thank you!
I LOVE this channel. You put good research together with great photos, interesting facts and commentary. This is definitely your calling and I'm sure this channel will grow.
Modern aggregate tends to be of uniform size, small pebbles mixed in to give it strength. At the Colosseum, I saw in a broken column that the agregate was rocks, broken bricks, and whatever they found lying around.
Smooth pebbles don't make good aggregate for any concrete. They need rough surfaces for the cement or mortar to latch onto during the curing process
I often think that the Roman concrete and their civil engineers are the foundation of their success as a civilisation.
@@robertbolstad9465 Marcus Vitruvius Pollio author of "De architectura", under the patronage of Augustus - not a slave; Apollodorus of Damascus. favorite of emperor Trajan, designed the famous Column (which still stands) and Forum of Trajan, and also apparently the Pantheon in the video - not a slave; Sextus Julius Frontinus, held high public offices under Domitian, was born of equestrian rank, and reached senatorial rank later in life (the most powerful elite of Rome aside for the emperors) - obviously not a slave. A lot of public construction work was done by the roman military: each legion had a chief architect/engineer responsible of the construction work the "praefectus fabrum", also responsible for the construction of military engineering works like artillery machines and camps/fortification - this a was a prestigious position definitely not held by slaves. What kind of bs are you trying to peddle and for what purpose I wonder?
Really love your channel! Thank you for addressing interesting questions and bringing history to life!
Great stuff. In short: i) Roman concrete (as a cheap construction material) was not widely used outside of Italy, ii) in large-scale Post-Roman structure's of Germanic and Greek traditions of building, concrete was largely irrelevant, and iii) it wasn't so much intellectually forgotten* as of little practical use, e.g. where stone, brick, or timber offered local, relatively cheap, and more or less durable alternatives to concrete blocks (i.e. for most places outside of Italy). ;o)
* Mortar as a concrete binding was a well known and increasingly widely used material, not least in Northern Europe, as more suited to the newer styles of building (cathedrals, castles, etc).
It wasn’t used outside the peninsula after the sack of Rome. Before then, buildings were constructed in the vain of Roman architecture with concrete. After the sack of Rome, where it lost power and influence and probably financial resources, it might have seemed irrational to overcapitalise on construction. Constantine gained influence in the Middle East after the sack of Rome and Christian architecture dominated as a form of public building. Serfdom was invented and the Byzantine Empire flourished. Possibly also people weren’t living as long and population growth was negative. Manual resources were not as readily available as it once was during reign of capital Rome.
"Mortar" is not one particular material. The Romans used hydraulic cement for mortar, which is the same glue that holds together Roman concrete. The Ziggurat of Ur uses bitumen (i.e. tar or asphalt) as a mortar. The Egyptians often used clay. During the Middle Ages (and really until the discovery of Portland Cement), Western Europe used non-hydraulic lime mortar; aka slaked lime.
Even if you're building a structure out of stone or brick, hydraulic cement (which is the essential ingredient of Roman concrete) is considerably advantageous to slaked lime mortar. Slaked lime mortar takes days to cure (if it ever cures at all in thick walls). It sets by absorbing carbon dioxide, so it must be exposed to air. It isn't nearly as strong as hydraulic cement, nor does it adhere very well to stone or brick.
Simple recipes for hydraulic mortar persisted in the East throughout the Middle Ages. When the Byzantines spread their knowledge to the Kievan Rus, they taught them how to make hydraulic mortar with lime and crushed pottery.
If Western Europeans knew how to make hydraulic cement, they almost certainly would have used it over slaked lime. Both hydraulic cement and slaked lime start out the same way- limestone must be quarried and baked. The next part is simply whether pozzolans like volcanic ash or crushed brick are added. That changes the chemistry and how it cures.
" it wasn't so much intellectually forgotten"
a long time ago as a history student I was shown a bit of medieval XIIth century mortar from before the Mongol invasion and it was harder than modern concrete (could not mark it with iron), and I was told told that's how I was supposed to date buildings older than 1241 ... it was not forgotten but as you say it was too expensive when good stone was available
we imagine that the Romans were like superengineers, but my guess is they did not really know what they were doing and we see only the happy accidents that survived while they built mostly of wood and rough cut stone and all the less happy accidents were mined for stone since then
outside the core of the Roman Empire there were more buildings constructed during the Middle Ages than during Antiquity ... also more written sources: what do we have that was written in Gaul or in Britannia from the Roman time ? All was about Rome or Constantinople, but as soon as the "barbarian" auxiliaries take over writers appear and are still preserved like almost everywhere including across the former borders of the empire
@@Ntyler01mil slaked lime mortar can be more elastic which could be useful with an expansive clay substrate of sudan for example vs natural limestone hills
@@Ntyler01mil slaked lime adheres very well to stone. find a stone wall and put it on there and come back in 5 years
Thank you for creating this. This video poses a question that's always puzzled me since seeing the Pantheon and reading "Brunelleschi's Dome." But I'm not yet convinced by this video's thesis that concrete was just no longer needed.
Very interesting video as always! Interesting because I never realised that the Roman concrete was relatively little used outside Italy around the empire. I didn't know also that the Church of Hagia Sophia was not made of Roman concrete but bricks! Of course with the decline of the Roman empire the Roman concrete was not required anymore and the Basilica was made of bricks. Thanks for sharing this very informative video 👍👍
The Catholic church wanted nothing to do with anything Roman. The Romans invented plumbing but Europe didn't get plumbing until centuries later.
@@dfirth224 wrong, the church used everything that is Roman including "recycling". What the church refused to do was building a pagan temple especially since the proclamation of the Edict of Milan in 313, which declared tolerance for Christianity.
@@dfirth224 The church is Roman. Medieval Europe was a totally Romanized society, from clothes, to customs, to language, to religion. The Roman empire itself was still around during the middle ages.
The Hagia Sophia does actually use Roman Concrete, as did many other structures in Constantinople, but the Romans also used bricks quite prolifically throughout the period of the empire.
Hagia Sophia was actually built to be fireproof through some ingenious methods.
The Roman Empire as we know never existed. There was a Roman Empire, but in Constantinople, the people called themselves roman!
you created such a great channel: than you very much! ☺️💝
1:50 Holy crap! Those squares are huge!
It's still the largest unreinforced concrete dome in the world today!
The amazing thing is that when you look at it from below it looks quite small.
Yes, what the romans did there is more impressive than various pyramids technically.
Perhaps it was done to make people not feel lost inside that giant dome?
Makes it look more to human scale, the roof, one would think, is not that high above your head.
Sort of the exact opposite of all buildings in Disney World, that appear to be bigger than they really are.
Are those squares considered coffers?
@@bentonrp Yes.
1st time finding your channel. Subscribed and liked. Good show.
Getting a notification that toldinstone has a new video out always makes my day. Thanks!!!
I liked seeing the concrete examples of what you were talking about.
Boom
That thumbnail is probably one of the coolest paintings I've ever seen
You're a wonderful narrator, and this video essay is very interesting.
Unfortunately, "While it is unclear when concrete originated, it is likely that attempts to make it occurred at several locations during the Neolithic period. Some of the oldest known examples include lime concrete floors at Yiftahel, southern Galilee, from around 7000 BCE, and Lepenski Vir, Serbia, around 5600 BCE.
Your videos have given me a concrete understanding of the ancient Roman world
There is a nice article in Wikipedia on Roman concrete
The Pozzolanic Ash is the ingredient that makes Roman concrete unique.
The Pozzolanic Ash comes from the volcanic fields around Naples, the Vesuvius area, and it apparently has a very rare chemistry. It was great luck that this rare ash fell into the hands of the Romans.
Salt destroys todays modern concrete, so there is an effort to use a concrete similar to Roman concrete in areas effected by salt. Even in areas not near the sea, modern concrete has been destroyed by using salt, such as, on icy concrete bridges here salt is used to melt the ice.
-
Thanks for the discussion on how Roman concrete was placed. The use of a very dry mix was the key, as modern concrete is quite wet and flows like mud and would destroy the brick forms.(1:05)
Quoting wikipedia is no different to quoting the Daily Mail. Well done. (sarcasm)
@@BotanyDegreePilkerton You beat me to it!
@@BotanyDegreePilkerton bbbb but it's the peoples encyclopedia! taglines don't lie...
@@BotanyDegreePilkerton Do you people not understand how to use wikipedia? After each claim, there will be a small number in brackets next to the sentence. At the bottom of the page, you find the source material for the claim. Those links are what should be used.
I've literally been wondering this for like 15 years but never took the time to find out. Thank you!
I'm, I will disagree to your saying that they could not calculate forces and tensions mathematically.It stupid to consider that they've built two enormous hippodrome just because the concrete was good.they had very good knowledge of forces stresses etc.In Spain they made a pool on top of a mountain and a tunel from the top to then center of the mountain, then they let the pool water flow in the tunel in the mountain, the potential energy became kinetic energy and all of it had no way to release but by breaking the mountain apart, thing is that they succeed it, so they knew how much water to add to do the job, the mountain had valuable minerals for the empire...I have a book on the hellenistic science and I can assure you that they were incredibly familiar with classic physics in the level we are today, they just had no formulas and so it was quite hard to pass this knowledge without studying a lifetime.They knew the 1st law of Newton by the meaning and not by the formula ΣF=ma.So yeah they knew very well what they were doing that's why their buildings still stand.
They could not calculate those things mathematically. You said it yourself "they didn't know the formulae". Moreover, you look at the pantheon now and think that they had to know exactly what they were doing, but that dome actually collapsed several times, and the one we have now is just the longer lasting one. Romans were builders but not mathematicians. Things stayed up because that time they did, not because they calculated it properly
@@giovanniriccardovigano3990 The Pantheon's dome never collapsed. It cracked and was rebuilt all through its history. The dome of Hagia Sophia collapsed I think 3 times. It was always rebuilt.
@@giovanniriccardovigano3990 omg...omg dude you have zero idea of the level of the mathematics of the period, just zero.The fact that they had no formulas doesn't mean that the people who knew how physics, weren't able to calculate.You want to tell me now that Diophantus wasn't able calculate(? ), he knew better mathematics than me and im physicist.They've built hydraulic robots,the book was know up to the middle ages, the muslim world attempted to make some of inferior quality and they succeed, the byzantines had a bunch of them in Constantinople to impress the barbarians, you want to tell me that they calculated the stress and the forces of the gas by mistake, or by guessing?
@@giovanniriccardovigano3990 considering the Antikythera Mechanism it would be weird to think the ancient world didn't have advanced abilities in mathematics and physics. It just wouldn't have been possible to build a machine like that without this kind of knowledge.
The reason many of these ancient structures remain erect is not the result of Newtonian physics, regardless of whether they had formulas or not. There WAS a knowledge and incorporation of sacred geometry. The utilization of the Fibonacci sequence, as an example. That is not something that necessarily needs formulas, but can be drawn out while creating blueprints/design, and it can be represented mathematically as well. This knowledge was used not only to make something be viewed as aesthetically pleasing, or even correct from some perspectives, but it was used to consider how the forces of nature would impact the durability of the structure. While we have to build strong foundations, incorporate steel in the framing, or come right back to retrofit a building to achieve a higher degree of confidence it won't crumble, the ancient architects needed none of that. Newtonian physics are not why these buildings last.
Well done video!
At 1:33 you show an old photo of a crack in the dome of the Pantheon.
Is it common for this to happen?
Does the Pantheon require a lot of maintenance? How would a crack like this be repaired? Would it be repaired using the original Roman concrete or something different? Thanks
Great stuff. I always give a "Like" when a video teaches me something. I think I have "Liked" every one of your videos.
Fax slatt
Ditto
So concrete wasn't completely forgotten. What a fascinating video, some actual new knowledge.
Would have been good if you’d defined what exactly ‘concrete’ is and whether Roman concrete was chemically different to modern concrete.
Not really - there are some minor differences but the basic recipes remain the same: burnt limestone, silica and ash.
There are a thousand other videos about that
@@ianchandley - It is important to understand the chemistry. Roman concrete is hydraulic cement plus an n aggregate. Hydraulic cement wasn't used at all in Western Europe throughout the Middle Ages. They settled for slaked lime mortars.
Hydraulic cement would be advantageous in many circumstances, so it's hard to argue they still knew the recipe but didn't bother to ever use it.
@@ianchandley the mineral and biological complex of sea water vs freshwater makes a huge difference
@@ianchandley simply "burning limestone" produces lime...the Roman innovation was incorporating natural pozzolans, which are a product of vulcanism. Modern concrete uses synthetic pozzolans...Portland cement,, fly ash, silica fume.
Lime is part of the recipe, but mostly to increase the alkalinity of the mixture (which activates the pozzolans).
My thoughts on why Concrete slowly phased out could also be from a lack of the fine volcanic powder due to overuse as well. But, I also dont know the volcanic activity too well without more info.
Here’s a strange compliment: Your speech patterns in reading remind me of Lt. Cmdr. Data on Star Trek. Or you could play a great Vulcan. Your diction is perfect. Your content is absolutely superb, btw. Subscribed!
What an astute and insightful observation! After reading your post I immediately pictured Data narrating the video. Kudos to you.
ruclips.net/video/f9zX_P7UZag/видео.html
His pronunciation of concrete is wrong
That was great mate, thanks for putting that together!
Producing baked lime in large quantities would have been an ordeal after the collapse of Roman resource management. If you can't produce enough concrete to pour a cathedral, you can still produce enough concrete to cement blocks of stone into an aggregate structural support. It takes a lot of wood to build a colosium, and first you have to mine and mill the limestone. The architecture of the medieval period in Europe is still pretty impressive, given that cement in an age without mass-production, was using concrete in mortar to glue together the building blocks of gothic cathedrals.
So what you are saying is that a collapse is an ordeal not the method of concrete.
You are assuming that there was no "mass production"...Check out the perfect 10.000 year old statues found throughout India....produced mathematically perfect...by some kind of forgotten tech.
@@johncampbell829 What would be their (the statues) name, then? It's quite difficult to find something like that just by description.
Thank you for such an interesting read
I love these videos. The narration is perfect.
Actually, it's horrible. His mis-pronunciation of "concrete" is a distracting affectation. What is amusing is that he doesn't do it consistently which shows it really is a deliberate affectation. To be fair, I've heard much worse.
Finally something interesting, i work in the concrete industry and have also pondered about this. Thanks man 👍
The simple fact that making good concrete was a precise and somewhat difficult process impeded its use. The ratios had to be very close and the materials not always easy to find. These difficulties combined with a loss of nearly everything related to advancement in culture must have contributed to the decline in concrete. Similarly, the Greeks also lost the ability to turn the drums needed for fine fluted, tapered marble columns and this skilled art did not return to Greece until modern times, much later than concrete.
I make roman concrete for my garden projects. I use local shells and my own soil. Takes about 3 hours to get your ratios right.
Love these videos. Thanks for doing them.
Great video. I just have one different thought about the end. I don't think concrete was irrelevant in the Middle Ages. It's 100% necessary for many things that would have improved their lives, such as clean water fountains, interior running water, pipes, radiant heat, steam rooms to bend wood for ship/furniture making, sewer systems, paving roads, building bridges, etc. (Remember, sets underwater?) But, like any other trade - it's a skill. One that can be quickly lost if a mere two generations go by without practice. Barbarians killing people who had skills they didn't need likely explains it. And general instability/starvation.
Recipe books are one thing, constructing a safe structure is another. That takes learning from masters. People likely got scared by failed revival attempts, and lost faith.
Without concrete, there was a decline in cleanliness and bathing, an increase in plagues, a near stoppage of bridge building, harbors couldn't be rebuilt after storms/quakes, floors for the average citizen became mud, (easily dug into by rodents,) and underground water storage became a pipe dream for your new community.
Concrete, just one of many techs that could have improved their lives if not forgotten. Making pipes, grading sewers, reservoirs and drainage tunnels, wells, and so importantly, paved roads...really really could have helped people. Especially after the invention of the horseshoe, which means horses didn't have to be put to death early if they wore down their hooves on hard surfaces. How many famines could have been averted if harvests never failed to be transported because of deep mud? The need for it was there, just sadly, it was lost.
The dark ages were an uncivilized period without a functioning economy and it meant technology like concrete was forgotten.
@@bighands69 That's just not true, because concrete and mortar was used all over Europe during the middle ages, and specifically Roman Concrete was used in Italy, and in the eastern half of the empire throughout the period.
"Dark Ages" is a pop history term. It's not a thing for actual historians except for specific regions at specific times where no sources have been preserved, like 5th century Britain. There was no "collapse of civilization" on mainland Europe, and main written sources survive.
@@histguy101
The Dark Ages is not a pop term it means a period of darkness as there was no culture in vast sections of Europe.
@@bighands69 "The dark ages" was a pejorative used by protestant and later enlightenment polemicists. If an historian uses the term, they're referring to something specific, like "the Greek Dark ages" from 1200-900bc, or "Dark Age Britain" roughly from 400-600ad. There's no sources, so it's dark, like we can't get a picture of life during that time. They don't use the phrase for medieval Europe. There's late antiquity (250/300 to 600/700). There's the early middle ages(roughly 500-1000), the high middle ages (roughly 1000-1250), and the late middle ages(1250-1500). The "Italian Renaissance" is during the late middle ages.
Mainland Europe is full of sources. There's more people writing in the 6th century than there was in the 2nd century when Rome was at its height. There's no such thing as some sudden collapse of culture, or civilization, or even the Roman empire itself, which ruled the Mediterranean until about 650-700, then waxed and waned for another 7 centuries.
@@histguy101
No it is not just a made up term. It literally means there was a period of darkness. Very little is known of that period and very little remains.
It is ironic that lots of roman architecture exists but very little exists of the dark age. It has even been noted that Roman Architecture in Britain is of a certain quality and when the Roman empire collapses there is a decline in quality.
As there was a dark age it is not even understood how Rome actually fell. There are many theories but little understanding or evidence.
Pretty good work there. You might have noted how the technique, of pounding or vibrating a small ratio of water throughout the mix, is now being used in dam construction.
I love the image of a farmstead built within a ruin.
If you are interested/curious about buildings, architecture, construction, history,....go see the Pantheon. Inside it and outside.
I've been there many times and it always blows my mind. You will be in awe.
The dome looks surreal at times. Literally as if it is painted on. But if you take a very close look at 0.10 or at 3.20, you will notice that there are no paintings on the higher part.
It is all concrete structure. And nearly 2000 years old. Incredible.
The romans utilized concrete rather than wood in and around Rome due to the lack of available tree's that one needs to provide lumber. When Rome ventured north in to Europe, the abundence of tree's allowed them to and they did utilize wood rather than concrete. Using wood which was more available in Europe vs the area's around Rome was considerably a faster more proficent process then the use of concrete.
The Romans still used a lot of wood. Many Roman apartment buildings were built with "opus craticium," which consisted of a timber frame skeleton with panels of wattle & daub (wicker frames covered in mud, essentially), mud brick, or other masonry. This type of construction was a big reason for why fires were so common in ancient Rome. Vitruvius complained about the construction method for how easily it burnt down, along with its susceptibility to moisture and decay. This means that much of Ancient Rome likely had an appearance that would be more readily associated with medieval London or Paris.
Even when buildings had masonry outer walls, wood was typically used for floors, roofs beams and internal partitions.
Long after Nero's building reforms following the Great Fire of 64, it appears that wood was still the principle construction material for many buildings. For instance, Herodian of Antioch tells us that the Praetorian Guard responded to urban unrest in 238 by burning down the apartment houses from which hoodlums were launching projectiles, adding that "great number of houses were made chiefly of wood.”
Timber frame buildings do have some advantages as well. They can be more earthquake resistant, and Vitruvius tells us that they were much more economical and faster to build. Vitruvius also tells us that the walls of such buildings were thinner, leaving more useable space.
@@Ntyler01mil good point
Romans only used trees when there was a lack of variety of materials. They did not use it because it was better.
Thanks for making sense.
Sadly, I have heard they also completely obliterated the woodlands of the north in places like Ireland and Scotland where so few trees remain today. The Irish and Scottish, too had a special relationship with nature, and even though attempts have been made, they have never been able to restore the land as it had previously been. Fortunately there is enough moisture there that the land would not be at risk of desertification as some areas of North Africa and the Middle East, but I find it pretty sad to know just how much the Romans destroyed around the world, and that earth still suffers from their selfish, power hungry, and destructive actions today.
Really cool video man you are good at this.
I would posit one more explanation: experience, or lack thereof
It is one thing to have access to the recipe and general description of how to use it, but another thing entirely to actually know how to use it.
It took roman architects and builders centuries to develop and refine their understanding of the material.
Once this practical knowledge was lost there was just no way of getting it back, since it would by necessity have been transmitted through non-literary means.
Thus, once demand declined, there would be fewer opportunities to train new masons, which would make it harder to comission new concrete buildings because the expertise would be harder to find, creating a vicious cycle.
Thanks for sharing this informative video!!!
This explains so much! We were just in Rome and very curious about such things.
Thank you for this wonderful history lesson
The more I hear about the things forgotten during the Middle Ages, the more it saddens me.
If the internet had been invented 2,000 years ago, imagine where humanity would be now. Imagine what we'd remember.
if we had the internet 2000 years ago everyone would be a massive degenerate
Great video man thank you!
Another excellent topic would be the overall decrease of Roman art into the child-like art of the Middle Ages. Or as my wife has stated so many times ‘they lost perspective’ ba-dum-tish’
Many thanks for taking the trouble to share this with us. I think the National Geographic did an article on the Port of Caesar-ea. I think about 800 large ship loads were imported of pozzolana because they did not trust the local material. Caesar-ea is pronounced with a 'C', and not a 'K' as in Kaiser.
I'm not sure the romans were tied to any set way of doing things in terms of materials. If it was more practical to use local "ingredients" then that would often be the case. Something designed for an emperor is obviously only going to use the best and that probably means imported from Italy. For most of the rest of the population if you already have ample supplies of water, chalk, gravel, sand, pumicite etc etc then all you really need is someone with a good knowledge of the process. I think the question remains mostly unanswered. The finer points of moulding and sculpting might have more to do with it's disuse.
he said that the concrete was mostly found/made in italy, so yea local is better
Fascinating video, seriously!!! I didn't know that a harbor had been built of concrete as late as the 6th century AD ! The part it dosen't explain though is why didn't they use concrete again during the renaissance. You would think that logically it must have been forgotten by then
Years ago, I was making railings for the front steps of a church in Kendal for English Heritage, when I heard the architect, (she would have been in her Thirties) tell the gnarly old Irish foreman, "No! It HAS to be goat´s hair mortar, horse hair simply WILL NOT DO." And she was right.
These things matter.
I set the railings into the stone with hot lead, I think I was the only person they could find who still did that, and they were careful not to ask if I had any insurance for the process.
Houses have a design life of less than fifty years now, concrete? Huh! You could probably use bloody marzipan.
Every time I see depictions of middle age life in Rome I think how wild it is to see people dwelling amongst and within these titanic ruins. A millennia old city of a million reduced to 20,000 over the course of a few centuries. And then I think of Detroit.
Thanks, this was enlightening. no mention though of shuttering, formwork, also no reinforcement was used, how was that avoided? Concrete is, apparently the 2nd most widely used substance after water & the third largest carbon dioxide emitter in the world
Roman concrete walls were almost always faced with a course of brick, which served as shuttering. For domes like the Pantheon's, huge wooden frameworks were constructed. Although primitive rebar was very occasionally used (iron bars were sometimes set into angles), the Romans generally assumed that their concrete was stable enough to need no reinforcement. Remarkably - at least in some cases - they were right.
Thank you for this - well done.
Interesting. Thank you
Being drunk af I've somehow found this video captivating as hell. Finally being drunk paid off, and that is all thanks to you. Good job!
Interesting. Looking forward to reading “Naked Statues, Fat Gladiators, and War Elephants”. Just bought it on Kindle.
It would be fantastic if you could link or refer to the sources you used for this video. I'm interested in checking by myself and having my own conclusions. I think it'd give this channel a more serious, professional way of explaining history :)
Otherwise, we can't know if the information of the video is real and accurate or not
Saw another Roman Concrete video that says the recipe using specific ingredients caused a change at the molecular level and actually gets harder the longer it is exposed to seawater. Amazing Stuff!!
4am I’m stoned, RUclips algorithm “wanna watch a video on Roman concrete?” Me “oh go on then!” thank you RUclips algorithm…
That Forum of Nerva picture is amazing. We have reports about what medievel people at Rome think about living between ruins of better times?
During the Renaissance, scholars and artists wrote essays and poems contemplating the wonders of the ancient city. But we know frustratingly little about what Rome's medieval inhabitants thought, since only a few travelogues survive.
In the Eastern Roman Empire it seems like the bricklayers union was powerful :).
Before the Union's went Democrat! LOL
@@chevychase3103 ratio
great vid! I like your tone, toldin!
01:30 The concrete used on the pantheon, is not structural, it is a veneer. Look at the crack. The structure is made of brick, and just covered in concrete to give it a "finished" look, without having to take a ton of time making sure all the exposed brick cuts needed and joints were uniform, laid uniform, and appealing to the eye. Even though it would look WAY more impressive had they not veneered it in concrete. The outside is all exposed brick, except for the north side, which is hidden behind stone. It has been changed so many times through out history, do we even know if the concrete veneer was even on the dome ceiling originally, or if it was added later, as a band-aid?
False
@@Ntyler01mil Really?, When i was there in Sept, it was all brick. Might want to take a look yourself. Im also a mason, who is a member of the union that was hired to figure out how Duomo in Florence was built, since no one in Italy knew. Cool NatGeo episode about it.
@Detonate Klubstompers Oh my god, you're right! 😃
...So all this talk about "The largest unreinforced concrete dome in the world," is about what, exactly?
Lol! Are you, and the people in this picture, the only people who knows this! 😂
@@klubstompers In the diagram in the vid, they used a brick wall as a "form" when laying the concrete, and left it in as part of the structure. Perhaps that is what you are seeing.
Dear Garrett,
What is the source of the final image of the Forum of Nerva? I've seen that and two or three other similar images a couple of times on the internet and would love to buy the publication it's from. Many a Google session has only yielded one small Italian PDF file on the Roman Imperial Fora. Would love to find the source!
I’m partner in a company that 3D prints houses out of concrete. We are now in R&D with geopolymers similar to the what the Romans discovered in the chemical reaction & tetrahedral bond occurring between silica & alkali. It can last thousands of years, is bulletproof, and heat resistant even at 3000 F. New evidence is pointing at the Pyramids of Giza also being geopolymer. Really fascinating stuff. Thanks for the video!
will see how long those houses last...hehehehh
Thanks for the content.
Great to see that you’re getting sponsors!
What??? ads are a bloody nuisance!!!
Fascinating, thanks for sharing👍
It's fascinating that the concrete in the Pantheon is still curing and getting stronger every day even now.
It's my belief that the Egyptians had a form of concrete even much earlier than the Romans or more precisely, before there was a Roman Empire, and used it to build most of the great pyramids at Giza, aside from the very few granite blocks that were used in some of the Interior spaces.
The crude concrete mix used by the Egyptians would be, and is, almost indistinguishable from natural limestone.
We tend to think of concrete as the modern concrete which is very uniform in its ingredients so that there's little difference between concrete in China and concrete in the US or Europe. This can close our minds to the possibilities of its existence in different forms in the distant past.
The idea that the ancient Egyptians used their own type of concrete makes the building of the pyramids a still phenomenal feat of engineering but, also a doable one as well.
Egyptian cement was plaster based for they used gypsum which is calcium sulfate
Concrete wasn't used for building the pyramids! Inner decoration, nothing else..