A 1700-yr old mystery possibly solved!

[Rich Fiscus]

Yes, I did.



Not again, I won't.



Ha! I will be spending a few days in Florence in late April and I totally will be visiting the Duomo, and its museum!

Some of the stainless fab work you guys do is breathtaking. Truly art. And like Roman concrete to the MIT guys, at times I have looked at work done by your craft and wondered "How did he even do that?"



On the topic of how hot the mix is and how quickly it cures, see below.

I participated in the construction of an international airport runway 200' wide and nearly a mile long. We batched the concrete on site. My role was labor relations. There was no strike, nor would there have been. Long story, but there was no "mob" connection. Only the union local business managers at the general presidents themselves.

The concrete got to the slip form paver in dump trucks and it set up immediately. Runways can actually land planes pretty much as soon as the concrete is placed. The mix is hot. But the surface requires more preparation. For example, longitudinal grooves are cut into it. For traction and weather reasons.

Rich has good reading comprehension and writing skills:



But now....these last two quotes seem to conflict. One suggest Romans used hot mixes and the other suggests long-set mixes. I suspect the latter is more true. For several reasons, including the handling requirements of hot mixes. Some mixes are so hot that they set up in minutes. When the water is added, the concrete must be placed NOW. A cubic yard of concrete weighs about two tons. They did not have our knowledge OR our heavy equipment.

And as I say, I'm not going to repeat what I already said except for this: Concrete....all concrete....continues curing for decades. It is stronger at sixty years of age than it was at twenty. Technically, concrete never stops curing. But it does "set" enough for practical use in about "X" period of time. "X" might be a week or month, but it can also be a half-hour or even less.

I think the reality is much more complex than that, although I’ll be the first to admit the chemistry of concrete is beyond my understanding. Once again, though, it comes back to how sophisticated the engineering that goes into modern concrete actually is.

And I understand how the curing process continues, which is why I used quotes. Mostly, though, I think we’re basically saying the same thing.

 

[MoireBass]

there’s no indication they knew why it worked, or that the salt in the water was part of the equation. We know all of that today.
... the purpose of this study was to reverse engineer the final product ... to understand how to duplicate particular properties the Romans stumbled across

Exactly, the Romans didn't know why it worked, but people in antiquity were keen observers and very good at exploiting what they found. Our ancestors were not stupid. (Well, it'd be more accurate to say that they weren't stupider than modern people. )

We have much better instruments and measuring devices, and vastly more understanding of why things work the way they do than people 1700 years ago. No one assumes that Roman concrete is the best-of-all-possible concretes. But it clearly has some desirable qualities that it might be possible to incorporate into our modern mixes.

Half the Colosseum is gone, not because it crumbled away under the elements, but because it went into Rome's churches and walls and bridges and street pavements.

And the posted pic shows the Colosseum subfloor/basement in the foreground, which would have been beat up and damaged and needed constant repair even when the place was in use. The Romans would lay huge wooden planks across the basement, dump tons of sand on top, and the animals and gladiators would emerge out of ramps and doors from the basement. And they'd flood the basement and row boats above to stage mock navel battles. That's hard on any structure. The seating areas of the Colosseum are in better shape.

 

[MoireBass]

Fun fact - apparently, building the pyramids in ancient Egypt was a way to pay your taxes. The Pharaohs required a share of people's working hours each year, not cash.

And the Pharaoh fed them and apparently gave them lots of BEER! People have tried to recreate the workers' beer recipe by examining microscopic traces left on drinking vessels from their camps.
You can see how this could work culturally. Kinda like multi-day hunting or ice-fishing trips today. Maybe all the men within a certain age range in a village would be required to leave home and work for one month a year for the Pharaoh. They'd eat high-protein food with a lot of meat and drink a lot of beer and teams would compete with each other to haul the most stone. And the women at home would kind of like to not have any men around occasionally.

 

[Old Fart]

.... I think we’re basically saying the same thing.

I think so too.

... No one assumes that Roman concrete is the best-of-all-possible concretes. ...

Some may be assuming this.

 

[hrodbert696]

As far as Roman concrete being superior to modern formulations, that’s more than a stretch. For starters, its longevity is at least partly due to insanely long curing time - as in decades vs weeks for modern concrete. It has lower plasticity, which the Romans certainly didn’t understand the importance of, and is generally a bit weaker, even after it “finishes” curing.

They definitely stumbled across polazzo for resisting saltwater, which made it ideal for use underwater. However, there’s no indication they knew why it worked, or that the salt in the water was part of the equation. We know all of that today.

As with all the recent research into Roman concrete in the last decade or so, the purpose of this study was to reverse engineer the final product, not to learn what the Romans knew, but simply to understand how to duplicate particular properties the Romans stumbled across, and integrate it into modern concrete engineering.

Exactly, the Romans didn't know why it worked, but people in antiquity were keen observers and very good at exploiting what they found. Our ancestors were not stupid. (Well, it'd be more accurate to say that they weren't stupider than modern people. )

We have much better instruments and measuring devices, and vastly more understanding of why things work the way they do than people 1700 years ago. No one assumes that Roman concrete is the best-of-all-possible concretes. But it clearly has some desirable qualities that it might be possible to incorporate into our modern mixes.

And the posted pic shows the Colosseum subfloor/basement in the foreground, which would have been beat up and damaged and needed constant repair even when the place was in use. The Romans would lay huge wooden planks across the basement, dump tons of sand on top, and the animals and gladiators would emerge out of ramps and doors from the basement. And they'd flood the basement and row boats above to stage mock navel battles. That's hard on any structure. The seating areas of the Colosseum are in better shape.

I think these are important points; we tend to mythologize the achievements of past civilizations, especially when we're not sure exactly how they did things, into there being some "lost mystery" of ancient "genius" or whatever. As often as not, the properties we marvel at may have been just the result of trial and error they stumbled onto. I wouldn't assume the Romans expected their concrete structures would prove more durable over centuries than stone ones. They figured out A way to make concrete, made it the way they knew, and lo and behold it turns out to endure.

I participated in the construction of an international airport runway 200' wide and nearly a mile long. We batched the concrete on site. My role was labor relations. There was no strike, nor would there have been. Long story, but there was no "mob" connection. Only the union local business managers at the general presidents themselves.

The concrete got to the slip form paver in dump trucks and it set up immediately. Runways can actually land planes pretty much as soon as the concrete is placed. The mix is hot. But the surface requires more preparation. For example, longitudinal grooves are cut into it. For traction and weather reasons.

There's a reason I included the caveat about being off my field of specialization - the larger point is that the form of a technology used in any society depends not only on what people know, but on its practicability under the social and economic structures of the society. The anecdote about the possibility of mob involvement in a Manhattan building was speculative, but illustrates the actual point. Likewise as far as slave labor in Roman building - slavery was certainly a pervasive reality of Roman life. Whether concrete-making in particular entailed slave labor, I have no idea, I'll leave that to the classicists. The point is that Romans had a different set of resources and constraints than we do.

 

[edward bloom]

I think these are important points; we tend to mythologize the achievements of past civilizations, especially when we're not sure exactly how they did things, into there being some "lost mystery" of ancient "genius" or whatever. As often as not, the properties we marvel at may have been just the result of trial and error they stumbled onto.

i don't know about the concrete thing enough to say one way or the other. however, regarding the pyramids, or gobeli tekli, i strongly disagree. it takes far more faith to believe they learned to do that by accident, than deliberately. you have to ignore mountains of obvious evidence. could we build a pyramid today? sure we could. can we build it with some of the massive stone blocks they used? nope. we cannot move them. same with the monoliths. they not only moved them but also over long distances, and later stood them up, without breaking them. that requires abilities that we do not have, in 2023. the idea that those feats of strength, precision, and complex math being accomplished with bronze age tools is ludicrous. zahi hawas is a liar

 

[HaphAsSard]

i don't know about the concrete thing enough to say one way or the other. however, regarding the pyramids, or gobeli tekli, i strongly disagree. it takes far more faith to believe they learned to do that by accident, than deliberately. you have to ignore mountains of obvious evidence. could we build a pyramid today? sure we could. can we build it with some of the massive stone blocks they used? nope. we cannot move them. same with the monoliths. they not only moved them but also over long distances, and later stood them up, without breaking them. that requires abilities that we do not have, in 2023. the idea that those feats of strength, precision, and complex math being accomplished with bronze age tools is ludicrous. zahi hawas is a liar

Unless one does not rule out the occult, it still boils down to two possibilities:
- either the civilisations you mention had a copious amount of empirical knowledge, by all means accumulated, organised and handed down over centuries but ultimately based on observation and simple experimentation (which is literally trial and error, just not a random, often repeating series, but one where each generation expands upon the T&R made by the previous ones)
- or they had a radically more complex, modern-like system of knowledge, with strong theoretical frameworks. This is not out the realm of what is possible, per se, but a lot harder to defend, because it would entail 0) a scientific method, 1) theories, 2) scientific instruments and 3) technological instruments, ALL of which somehow lost to time. Unlike the Göbekli Tepe folks, ancient Egyptians had writing and liked using it: even granting that imperial scribes had no reason to know anything about engineering, shouldn't there be some surviving hieroglyphic whiff of the fact that contemporary architects designed and built monuments on the basis of some sort of Galilean/Baconian science, beside the puzzling grandiosity of the monuments themselves?

 

[Tom Bomb]

Who was it, Archimedes, who said, 'Give me a place to stand, and I shall move the world.'?

There's some good leverage in that crusty, old, cold-case quip. And then, there's the Archimedes Screw. I don't know what to make of it — that'd be like pushing fertilizer uphill. And, you'll likely find some very strange fruit in the Hanging Gardens, if you can find it, back when Archimedes wasn't even a glint in his old man's eye.

All is not lost. Let there be 'rock'.
​

 

[edward bloom]

Unless one does not rule out the occult, it still boils down to two possibilities:
- either the civilisations you mention had a copious amount of empirical knowledge, by all means accumulated, organised and handed down over centuries but ultimately based on observation and simple experimentation (which is literally trial and error, just not a random, often repeating series, but one where each generation expands upon the T&R made by the previous ones)
- or they had a radically more complex, modern-like system of knowledge, with strong theoretical frameworks. This is not out the realm of what is possible, per se, but a lot harder to defend, because it would entail 0) a scientific method, 1) theories, 2) scientific instruments and 3) technological instruments, ALL of which somehow lost to time. Unlike the Göbekli Tepe folks, ancient Egyptians had writing and liked using it: even granting that imperial scribes had no reason to know anything about engineering, shouldn't there be some surviving hieroglyphic whiff of the fact that contemporary architects designed and built monuments on the basis of some sort of Galilean/Baconian science, beside the puzzling grandiosity of the monuments themselves?

well, if by occult, you mean... supernatural, i would find it an interesting speculation, but i have a feeling things would go off the rails with a quickness. sometimes, people tend to take that sort of thing in funny ways.

it's not just the size of some of the blocks. it's the precise location of cheops, it's orientation, and the way it's measurements shake out. we know from unrelated finds that they knew the size and mass of the earth and moon, distance to the sun, number of planets in our solar system. that's not bronze age knowledge. sure, there could be reasons why they didn't talk about how they did it, or maybe egypt's minister of antiquities is hiding stuff? maybe whoever did all that, put their information in one place, and something happened to it? i have no idea. it's not a stretch to think not everything would survive that long. all we can do, is ask the owl...

Who was it, Archimedes, who said, 'Give me a place to stand, and I shall move the world.'?

There's some good leverage in that crusty, old, cold-case quip. And then, there's the Archimedes Screw. I don't know what to make of it — that'd be like pushing fertilizer uphill. And, you'll likely find some very strange fruit in the Hanging Gardens, if you can find it, back when Archimedes wasn't even a glint in his old man's eye.

All is not lost. Let there be 'rock'.
​

i can't imagine what the lever would look like to move a 1,000 ton stone up the side of a pyramid, or from a quarry 500 miles away. as crazy as such a sight would be, you'd think somebody would have talked about it, or drew a picture of it. hard to tell. we've had cell phone cameras for decades now, and still don't have a good picture of bigfoot
​

 

[Tom Bomb]

Don't limit your thinking. How many passes could there be, in a well planned goal, with each pass being a lever against the ball, towards the goal? Is a wheel a lever, a gentle slope, an army, a scaffold, a body of water? It's a rhetorical question.

​

 

[RichterScale]

ancient Egyptians had writing and liked using it:

Here's a scenario that I find quite possible and fun to think about:
Many of the monolithic structures around the planet are from an era before the end of the last ice age. The last ice age ended catastrophically and in a geologic instant. Sea level rose 400'. Seeing how most humans settle on coastal regions, any survivors would've been sent packing inland and uphill. I would imagine it would've essentially sent humans back into the stone age for quite some time.
5-6000 yrs later, population rebounded and civilization reappeared.
Many cultures discovered ancient structures and rebuilt around and/or on top of them.
So, the Egyptian civilization that developed the writing/hieroglyphics that we know of today, were developed within the last 6000 yrs and things like the large pyramid and Sphinx were already ancient structures that they didn't build. They didn't know who built them or how they did it, any more than we do today.

 

[edward bloom]

Here's a scenario that I find quite possible and fun to think about:
Many of the monolithic structures around the planet are from an era before the end of the last ice age. The last ice age ended catastrophically and in a geologic instant. Sea level rose 400'. Seeing how most humans settle on coastal regions, any survivors would've been sent packing inland and uphill. I would imagine it would've essentially sent humans back into the stone age for quite some time.
5-6000 yrs later, population rebounded and civilization reappeared.
Many cultures discovered ancient structures and rebuilt around and/or on top of them.
So, the Egyptian civilization that developed the writing/hieroglyphics that we know of today, were developed within the last 6000 yrs and things like the large pyramid and Sphinx were already ancient structures that they didn't build. They didn't know who built them or how they did it, any more than we do today.

that's something i've considered (sort of) and it kinda makes sense. certainly, if there were something that caused a huge decrease in population in a very short period of time the loss of science and tech would for sure happen. much of it would become useless anyhow. although most of the time the knowledge of how to do a thing comes from the knowing of many other things, that enable you to do much more. it suggests that what we still lack would massively change life as we know it today, if we figured it out tomorrow. on the other hand, if some near-extinction event happened right now, there would be no records of the knowledge we lost after 500 to 1000 yrs had passed. as far as i know, we don't have a repository for that knowledge that is designed/capable of surviving what nature might do in that period of time. you can bury it or put it in a cave, but if a glacier comes along, it's all gone

 

[Tom Bomb]

Turkish prosecutors have begun gathering samples of buildings for evidence
on materials used in constructions.(AP Photo: Hussein Malla)
​

Türkiye issues more than 130 arrest warrants for building contractors as death toll passes 33,000. Gone for all money.
​

 

[hrodbert696]

Unless one does not rule out the occult, it still boils down to two possibilities:
- either the civilisations you mention had a copious amount of empirical knowledge, by all means accumulated, organised and handed down over centuries but ultimately based on observation and simple experimentation (which is literally trial and error, just not a random, often repeating series, but one where each generation expands upon the T&R made by the previous ones)
- or they had a radically more complex, modern-like system of knowledge, with strong theoretical frameworks. This is not out the realm of what is possible, per se, but a lot harder to defend, because it would entail 0) a scientific method, 1) theories, 2) scientific instruments and 3) technological instruments, ALL of which somehow lost to time. Unlike the Göbekli Tepe folks, ancient Egyptians had writing and liked using it: even granting that imperial scribes had no reason to know anything about engineering, shouldn't there be some surviving hieroglyphic whiff of the fact that contemporary architects designed and built monuments on the basis of some sort of Galilean/Baconian science, beside the puzzling grandiosity of the monuments themselves?

This. When I spoke of ancient civilizations "stumbling" onto engineering skills through "trial and error," I didn't mean on a single occasion or in a single person's lifetime. We tend to "telescope" time when thinking about the ancient past, and underestimate just how long traditions had been evolving. By the time the Fourth Dynasty took power, the foundations of Egyptian empire were as far removed from them as Christopher Columbus is from us, and pre-dynastic civilization centuries older still. Similar can be said of a lot of astronomical observations and the math related to them.

 

[edward bloom]

i still think there is something being left out/glossed over
how does it make any sense that the rest of that region was in the bronze age, but someone managed to build the pyramids and know complex math? somehow they kept all of that knowledge from being leaked? all of it? over the hundreds of years, as you say the distance between columbus and us. maybe it was cumulative, maybe it wasn't. somehow, the phrase "standing on the shoulders of giants" keeps popping into my mind.
such feats would make them men of renown.
mighty men, indeed.

 

[MoireBass]

I think the thread on research into Roman concrete has run its course - and then some.

How about you guys starting a new thread on ancient technology including how they built the pyramids? (Maybe a better title though.) I've got a couple of thoughts on that, and it seems like that discussion is far bigger and really deserves its own thread.

BTW - the full quote is "Give me a lever long enough and a fulcrum on which to place it, and I shall move the world."- Archimedes

 

[hrodbert696]

i still think there is something being left out/glossed over
how does it make any sense that the rest of that region was in the bronze age, but someone managed to build the pyramids and know complex math? somehow they kept all of that knowledge from being leaked? all of it? over the hundreds of years, as you say the distance between columbus and us. maybe it was cumulative, maybe it wasn't. somehow, the phrase "standing on the shoulders of giants" keeps popping into my mind.
such feats would make them men of renown.
mighty men, indeed.

Ummm... Egypt WAS in the Bronze Age. They weren't using iron tools or anything else neighboring civilizations didn't have.

Knowledge WAS shared. The Babylonians and Chaldeans had a reputation for math and astronomy on par with the Egyptians. There's no question of knowledge somehow not "leaking." People traveled and shared knowledge a lot.

I think you're approaching this entirely the wrong way around. People like to eat, to raise families, to enjoy themselves once in a while. Some also like to domineer and exercise power over others, etc... "Building pyramids" is not really a necessity or high priority thing for most people to do, whether they have the means for it or not. Even in Egypt, Khufu's "Great Pyramid" at Giza was a one-off; subsequent pyramid-building was much more modest, and several projects were abandoned. It isn't as though there's some secret key to building a pyramid where anyone who had the key would naturally do it. People are going to invest their resources in a way that's sensible for them to meet their own goals. It's kind of like building skyscrapers; sure, from time to time someone wants the bragging rights that they built the tallest one ever. But for the most part, what they want is office space, and they're going to invest the resources they're willing to spend on a building that meets their needs and they can pay for.

No one else built another Great Pyramid, because there wouldn't have been a point, certainly not a point worth investing that level of labor to. If you look over at Mesopotamia, they DID put up grand monumental structures - Ziggurats. They weren't as big as Khufu's pyramid - the biggest was about 1/3 of the height. The oldest (and smaller) ziggurats are from earlier than Old Kingdom pyramids, but also new ones continued to be built considerably later. Why weren't ziggurats as big as pyramids? Partly for practical reasons - if Herodotus is to be believed, there were religious shrines and ceremonies at the tops of them, so people needed to actually be able to get up there (and possibly still be seen and heard by crowds below).

Also, what IS unique about Egypt is its geography - a single HIGHLY fertile river valley in the middle of desert. It was thus densely populated and easily unified. Khufu was able to make a statement about his central power by mobilizing the resources of the whole country for his tomb. Even under its various empires, Mesopotamia was never that centralized; each empire was a conglomeration of autonomous city-states where one temporarily imposed its will on the rest. Forced labor was deeply resented (see the Cyrus Cylinder). Mobilizing the labor force Khufu did simply wasn't practical - and indeed, probably proved impractical for subsequent Pharaohs too, considering the generally more modest dimensions of subsequent pyramid projects.

The ancient Egyptians didn't have any secret sauce. If you look at their temples, the pillars are thick and spaced close together - there's hardly any real open indoor space. The reason is that they didn't know how to hold a roof up over a large enclosed area without its collapsing (see earlier posts about Roman and Renaissance dome-building). The weight-distribution problem was beyond their knowledge. Roman domes, and then especially medieval pointed arches and flying buttresses, were miles beyond anything the Egyptians ever figured out architecturally. Pyramids have some clever narrow interior passages and burial chambers, but the basic idea is very simple - a big solid triangle of blocks, the simplest and most stable structure one can build. What's breathtaking about them isn't any complexity, but their sheer scale.

 

[gln1955]

The fact that the ancient Egyptians understood the math need for building the pyramids as well as all of the astronomy they did should not be a mystery. Out of all the sciences, math only requires thought and reasoning but no other supporting technology. There is no reason any ancient civilization couldn't figure out geometry, algebra or trigonometry. As for astronomy, they lived lived under clear skies nearly every night and had plenty of time to observe and draw conclusions from repeating patterns. People in ancient times were much more attuned to their environment than we in modern complex societies are.

There are several theories about how the blocks were quarried, transported and assembled. We just don't know which methods or maybe a combination of methods were actually used. It wasn't easy by any means but possible given a big enough commitment of time, manpower and other resources. As so nicely explained by our resident history professor, the stars have to align for a society to be able and willing to commit to mega building projects.

 

[edward bloom]

i think we prob should give this topic it's own thread. i'm pretty impressed they've put up with us this long. if one of you guys creates it, i would see you there. so far, it's been a fun discussion

 

[Tom Bomb]

Well, you know what they say. The concourse of true love never did run smooth.
​