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Ancient Roman Concrete Is About To Revolutionize Modern Architecture
schwit1 sends this news from Businesweek:
"After 2,000 years, a long-lost secret behind the creation of one of the world's most durable man-made creations ever — Roman concrete — has finally been discovered by an international team of scientists, and it may have a significant impact on how we build cities of the future. Researchers have analyzed 11 harbors in the Mediterranean basin where, in many cases, 2,000-year-old (and sometimes older) headwaters constructed out of Roman concrete stand perfectly intact despite constant pounding by the sea. The most common blend of modern concrete, known as Portland cement, a formulation in use for nearly 200 years, can't come close to matching that track record. In seawater, it has a service life of less than 50 years. After that, it begins to erode. The secret to Roman concrete lies in its unique mineral formulation and production technique. As the researchers explain in a press release outlining their findings, 'The Romans made concrete by mixing lime and volcanic rock. For underwater structures, lime and volcanic ash were mixed to form mortar, and this mortar and volcanic tuff were packed into wooden forms. The seawater instantly triggered a hot chemical reaction. The lime was hydrated — incorporating water molecules into its structure — and reacted with the ash to cement the whole mixture together.'"
Can this discovery of old stuff be patented today, or is the fact that the romans did it so long ago constitute prior art? Or will the argument go like "We don't have a treaty with the Roman Empire regarding Intelectual Property Rights, an nobody did this in our country yet, so sure, go ahead an patent it"...?
Question for religious people: where do unrepentant masochists go when they die?
Digitus impudicus ad hodierna effercio. MM anni? Mirum dictu!
Those who can make you believe absurdities can make you commit atrocities. - Voltaire
I find it odd that there are claims this is new information. Didn't Vitruvius describe it in his De Architectura, written about 15 BC?
http://en.wikipedia.org/wiki/De_architectura
Perhaps the story is confusing the known composition with some mechanism that the new study discovered.
So there's no such thing as lime and tuff? Of course we can use this method today, if they really have the formula now. I think Portland cement has been used for the last 200 years because it is cheap. This will not be as cheap, but in applications where corrosion is a particular issue, e.g. dams and in particular in salt and brackish water, it might likely be used.
I plan to build my next structure with Roman Concrete and Rearden Steel...
All right, but apart from the sanitation, medicine, education, wine, public order, irrigation, roads, the fresh water system and public health, what have the Romans ever done for us?
Ha. That's not dictated by unions. It's dictated by contractors that don't have any incentive to finish the job in a reasonable amount of time. When incentives are built into the contract, they finish on time.
didn't most countries move to a first to file system? I'm pretty sure Julius didn't get to the Patent office on time for this one.
Hi! I make Firefox Plug-ins. Check 'em out @ https://addons.mozilla.org/en-US/firefox/addon/youtube-mp3-podcaster/
The secret to Roman concrete lies in its unique mineral formulation and production technique.
Oh? Really? Its not becuase the Romans made sacrifices to Jupiter? They didn't make their concrete with a recipe given to them by ancients astronauts? The secret lies with thier recipe and technique? Who knew?
Python: 'And then suddenly you have a language which says "we're all stuck with whatever the whiniest coder wants".'
Cement is not concrete. Concrete is made of cement plus aggregate.
Researched and published over 30 years ago. Known technology for decades. Could reduce the 7 % of total carbon dioxide output on planet generated by cement production.
Anything changed in 3 decades - will anything change in the near future in a billion $ industry?
BOHA!
From http://newscenter.berkeley.edu/2013/06/04/roman-concrete/ While Roman concrete is durable, Monteiro said it is unlikely to replace modern concrete because it is not ideal for construction where faster hardening is needed. But the researchers are now finding ways to apply their discoveries about Roman concrete to the development of more earth-friendly and durable modern concrete. They are investigating whether volcanic ash would be a good, large-volume substitute in countries without easy access to fly ash, an industrial waste product from the burning of coal that is commonly used to produce modern, green concrete. “There is not enough fly ash in this world to replace half of the Portland cement being used,” said Monteiro. “Many countries don’t have fly ash, so the idea is to find alternative, local materials that will work, including the kind of volcanic ash that Romans used. Using these alternatives could replace 40 percent of the world’s demand for Portland cement.”
Application specific concrete that has stood up for two millenia beats our common, everyday, casual-use concrete. Compare it to the stuff used for capping deep water oil wells and I'll be more impressed. [/sarcasm]
Those people who think they know everything are a great annoyance to those of us who do. (Isaac Asimov)
From http://en.wikipedia.org/wiki/Pozzolana
Cook D.J. (1986) Natural pozzolanas. In: Swamy R.N., Editor (1986) Cement Replacement Materials, Surrey University Press, p. 200.
Lechtman H. and Hobbs L. (1986) "Roman Concrete and the Roman Architectural Revolution", Ceramics and Civilization Volume 3: High Technology Ceramics: Past, Present, Future, edited by W.D. Kingery and published by the American Ceramics Society, 1986; and Vitruvius, Book II:v,1; Book V:xii2.
McCann A.M. (1994) "The Roman Port of Cosa" (273 BC), Scientific American, Ancient Cities, pp. 92–99, by Anna Marguerite McCann. Covers, hydraulic concrete, of "Pozzolana mortar" and the 5 piers, of the Cosa harbor, the Lighthouse on pier 5, diagrams, and photographs. Height of Port city: 100 BC.
Mertens, G.; R. Snellings, K. Van Balen, B. Bicer-Simsir, P. Verlooy, J. Elsen (2009). "Pozzolanic reactions of common natural zeolites with lime and parameters affecting their reactivity". Cement and Concrete Research 39 (3): 233–240. doi:10.1016/j.cemconres.2008.11.008. ISSN 0008-8846. Retrieved 2009-03-23.
no, we're the People's Front of Judea! bloody Romans.
Si tacuisses philosophus mansisses.
If God forks the Universe every time you roll a die, he'd better have a damned good memory.
I doubt whether it would help. Since Roman concrete can't be steel-reinforced, it would just crumble if ice heaved it upwards because it wouldn't have steel inside to hold it together. It wouldn't help with cracks, because even concrete roads are still surfaced with a few inches of asphalt (at least, in Florida... maybe things are different "up north"). AFAIK, the endless annual resurfacing would still be necessary, because 99% of the potholes and cracks are in the top layer of asphalt, not the structural concrete roadbed below.
Where the Roman concrete might be MORE useful is environments like causeways, by providing a hard shell around the structural foundation that protects it from erosion. Where it might become a bit dangerous is if it ends up protecting the structural reinforced concrete from VISIBLE damage, but doesn't prevent the steel from rusting away on the inside until its tensile strength gets reduced to the point of being dangerous even though it "looks fine" on the outside.(*)
(*)For those who don't know, reinforced steel consists of steel bars + concrete because concrete has tremendous compressive strength, but terrible tensile strength. Apply force in any direction besides straight down, and concrete just breaks away or crumbles. In contrast, steel has a lot of tensile strength (it tends to stretch and bend rather than snap), but terrible compressive strength. As a matter of good luck, steel & concrete have mostly identical expansion rates when heated & cooled, and form a very strong chemical bond to each other (get concrete splattered on your car, and once it dissolves the paint and makes contact with the steel body it's NEVER coming off). The combination allows concrete to provide the compressive strength, and the steel to provide the tensile strength. Without steel, an elevated freeway would have to be built from arched vaults. With steel, you can support it with flat beams. Of course, if you approximate a "classical" form like an arch, you'll be working WITH the concrete and adding strength, but steel is what allows us to build things like a 40 foot road deck cantilevered from a single support column, or support a skyscraper like Citigroup's midtown headquarters from support columns that are located in the middle of each wall instead of at the corners.
Admit it. You all learned Latin on the off chance that you would find yourself in the past left to survive by your own wits.
Or because it was compulsory in those days, at least at my school. And since it was taught the "old-fashioned" way (using sadistic brutality, such that the Centurion's Latin lesson in Life Of Brian was eerily familiar), I actually learned the cursed lingo.
All interesting or useful topics were forbidden. Time travel to escape your teachers and/or homework deadlines would have been one of these.
Those who can make you believe absurdities can make you commit atrocities. - Voltaire
Question is - why is it necessary for concrete to be reinforced? Obviously, the Romans didn't have steel or iron rebar. They formed and poured their structures without any rebar, and they've lasted a couple thousand years. It seems more than obvious that our architects and engineers can learn a few things from the Romans.
IANASE (structural engineer), but from my understanding one key difference that reinforced concrete confers is that it allows the concrete to be prestressed to perform better under tension. Concrete (Roman or modern) is just fine under compression, so it can support a prodigious amount of weight loading down on it. However, once you try to span an area then the concrete in the middle of the span is normally under tension. As you can imagine, this often leads to cracking and outright failure. Furthermore, it's why the Romans had such a predilection to using arches and domes, which keep the concrete predominantly under compression rather than tension.
Think about it this way: our highway bridges couldn't be built the way they are if we were using unreinforced Roman concrete; however, if the concrete is prestressed then the tensile forces are balanced by the compressive forces. This also allows us to do many other interesting things with architecture that weren't feasible before.
I have wondered about whether something like carbon fiber could be used in the future to produce prestressed concrete that wasn't as prone to corrosion as the steel rebar-based approach. Something like that might be the best of both worlds. Okay, so I just Googled and it looks like at least one carbon-fiber approach is already patented.
Just as an aside, the Romans were quite ingenious when it came to implementing their architectural application of concrete. I read that when Hadrian ordered the construction of the current version of the Pantheon, the Roman engineers were faced with difficulty designing a dome that would not collapse under its own weight (again, tensile forces and concrete are not friends). The Romans overcame this by reducing the density of the concrete in the dome by using pumice in the aggregate and reducing the thickness of the concrete as the dome progressed. The dome of the Pantheon remains the largest unreinforced concrete dome in the world—not because we can't replicate the techniques, but because reinforced concrete performs so much better under tension.
Prestressed concrete
I'm sure that Roman concrete greatly varied in quality. Every batch was an experiment using local materials.The crap that didln't last for 25 year is long gone. All we have left to look at today are the results of successful experiments. And it is a wise thing to learn from it. But to consider everything the ancients built as evidence of their genius disregards the winnowing of time. Good stuff lasts, bad stuff falls apart and is discarded.
Roman concrete can't be steel-reinforced
Why?
it's time to rediscover Damascus steel.
It can be, but then it loses it's main advantage as the steel (and the concrete containing it) needs to be replaced after a while.
Roman engineers were faced with difficulty designing a dome that would not collapse under its own weight (again, tensile forces and concrete are not friends)
IIRC in a dome all the stresses are compressive. It's like an arch rotated around an axis, is one way to look at it. Also, it's not essential to prestress the concrete in order for reinforcement to add tensile strength. Sorry for being pedantic, but a compulsion is a terrible thing to waste.
You mean roman_mir? He seems to be her biggest fans.
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
Fiberglass threads are sometimes added to concrete to eliminate the need for rebar/remesh. I used that on my truck's parking spot in part because it was only slightly more expensive per yard than the price of concrete+remesh, and since it could be poured thinner without cracking slightly less material was necessary. The fiberglass makes getting a smooth finish on it pretty much impossible, which was fine since my concrete finishing skills are not really up to snuff anyway.
"Think about how stupid the average person is. Now, realise that half of them are dumber than that." - George Carlin
If you want to see an example of Roman concrete, look at photos of or just go to Rome and visit the Pantheon, that great domed temple nearly 2000 years old. It's completely in tact and the dome is made of that marvelous concrete. No rebar, no reinforcement, just concrete. There is no way in hell that temple would have stood this long if it contained any kind of metallic rebar other than something made of gold or other material that doesn't corrode when exposed to the elements, and if it did the building would have been torn down to get to the metals inside as with the Colosseum. That's what happened to the bronze tiles that originally covered the dome.
It's really quite a simple choice: Life, Death, or Los Angeles.
Even without prestressing, (which reinforced concrete does allow) reinforcement provides additional tensile strength. Concrete's tensile strength is no more than 10% of its compressive strength which means it's nothing to write home about. You can get reinforcement from fibres (which is why the ancients would add straw to clay to make bricks).
The point is that while pretensioning does give you added tensile resistance (by converting the inital tension to a reduction of the pre-imposed compression), reinforced concrete does not require pre-tensioning to reinforce concrete in tension, and in most cases just the presence of rebar is enough to provide the required tensile resistance. Pretensioning will be used when larger spans (and therefore larger tensile stresses in some parts of the beams) are required.
I like my dinosaurs feathery, and my pterosaurs hairy (or is it pycnofibery?)
true
Not true
IIRC in a dome all the stresses are compressive.
Eh... I am fairly certain it depends on the arch/dome curvature. Here's a HowStuffWorks cite:
"But as with beams and trusses, even the mighty arch can't outrun physics forever. The greater the degree of curvature (the larger the semicircle of the arch), the greater the effects of tension on the underside of the bridge.
It makes sense: if you have a very low curvature the arch/dome trends toward being a flat beam and is obviously is experiencing tension. You can try to counterbalance that by building more support structure to counteract the tension by compressing the low curvature beam, but then we are quickly approaching the concept that prestressed concrete accomplishes intrinsically.
I will say that it is a shame we don't see as many flying buttresses anymore (haha).
It's amazing how advanced the Romans were and how some of their technology stayed "lost" for so long. The fall of Rome was a great societal reset. There may be another at hand.
Wansu, th' chinese sailor
From the headline one would think that this is the "secret ingredient" to the Roman concrete: "The lime was hydrated — incorporating water molecules into its structure — and reacted with the ash to cement the whole mixture together"
However, this is pretty much how portland cement (the modern binder in concrete) reacts with water to form the concrete with the agregate. Reading the article, however this is what matters:
"One is the kind of glue that binds the concrete’s components together. In concrete made with Portland cement this is a compound of calcium, silicates, and hydrates (C-S-H). Roman concrete produces a significantly different compound, with added aluminum and less silicon. The resulting calcium-aluminum-silicate-hydrate (C-A-S-H) is an exceptionally stable binder."
"At ALS beamlines 5.3.2.1 and 5.3.2.2, x-ray spectroscopy showed that the specific way the aluminum substitutes for silicon in the C-A-S-H may be the key to the cohesion and stability of the seawater concrete."
"Another striking contribution of the Monteiro team concerns the hydration products in concrete. In theory, C-S-H in concrete made with Portland cement resembles a combination of naturally occurring layered minerals, called tobermorite and jennite. Unfortunately these ideal crystalline structures are nowhere to be found in conventional modern concrete."
"Tobermorite does occur in the mortar of ancient seawater concrete, however. High-pressure x-ray diffraction experiments at ALS beamline 12.2.2 measured its mechanical properties and, for the first time, clarified the role of aluminum in its crystal lattice. Al-tobermorite (Al for aluminum) has a greater stiffness than poorly crystalline C-A-S-H and provides a model for concrete strength and durability in the future."
So basically, there is alimunium in the crystaline structure of Roman cement that contributes to the differences in performance over time (not raw strength). Another factor that may impact durability that is not covered here but that civil engineers will know well is the fact that modern cements are more alkaline than even early Portland Cement productions. As a result, they tend to react with the silicates in the aggregates of the cement (phenomenon known as alkali-aggregate reaction). If you see concrete with cracks that look wet even when it's not raining, that's a symptom of this effect. The reaction with the aggregates causes an expansion within the concrete which builds ups stresses locally and result in those cracks, with obviously unfortunate effects on the longevity of concrete structures.
I like my dinosaurs feathery, and my pterosaurs hairy (or is it pycnofibery?)
You are correct. I have known about it for some time...I think it is pozzolan or similar - nothing lost or rediscovered.
they also used to put blood in some of their cement.
Exactly. The hydraulic reaction described in the summary is the very same as used in today's concrete. As are the wooden casks. (Today we also use to throw a lot of iron in there to deal with tension, but that doesn't affect erosion.) The real deal is a lot deeper in TLA.
Oh, the beautiful gloss of greality!
From the press release: "The resulting calcium-aluminum-silicate-hydrate (C-A-S-H) is an exceptionally stable binder."
Now, if they could only make it transparent...
I like my dinosaurs feathery, and my pterosaurs hairy (or is it pycnofibery?)
I don't understand. Why don't those fly-ash-challenged countries just burn more flies? Are flies in that short a supply?
wake up and hold your nose
Steel has no problem with compressive strength, it's just a lot more expensive than concrete.
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No, you misunderstand me. I'm making no claims about the quality of modern concrete, everything I've heard says Roman concrete is vastly superior. What I'm saying is basically that if the Romans had used iron rebar then their structures would have long since crumbled as the expanding corrosion split apart the concrete. Roman concrete lasts. Iron doesn't. And if you encase iron in concrete then the concrete will eventually be shattered because it doesn't have the tensile strength to withstand the expansive forces (if it had the tensile strength you wouldn't need the rebar)
--- Most topics have many sides worth arguing, allow me to take one opposite you.
... I read that when Hadrian ordered the construction of the current version of the Pantheon, the Roman engineers were faced with difficulty designing a dome that would not collapse under its own weight (again, tensile forces and concrete are not friends). The Romans overcame this by reducing the density of the concrete in the dome by using pumice in the aggregate and reducing the thickness of the concrete as the dome progressed....
That is not the only interesting weight reducing methods they used. They also used a form of hollow core composite construction - embedding hollow clay pots in the wall to reduce its density, and the done itself is a ribbed structure, with vertical and horizontal ribs framing those "decorative" (but highly functional) square indentations in the inner surface.
Some speculate that scale and partial full scale engineering models were used to perfect the design and construction techniques.
Starships were meant to fly, Hands up and touch the sky - Nicky Minaj
Steel has no problem with compressive strength, it's just a lot more expensive than concrete.
It's not just cost. If you formed a freeway support column from a solid block of steel having dimensions of 5x10x40 feet, it would be impossible to transport to the site or place into position, and even more impossible to join to anything comparably large. You simply couldn't get the middle part of the contact points hot enough to weld, without damaging the structural integrity of the remainder of the beam/column while doing it.
In the real world, steel beams have to be some variant of a tube, box, I-beam, or C-channel/stud to enable them to be placed. The problem THEN is that many steel arrangements can't even support their own weight until they're all fastened together, and if something pushes them far enough to kink or bend, they fail rapidly and completely. For example, a futon made from steel tubes might be very strong, but if someone heavy falls into it, the whole thing can collapse the moment the first tube gets even slightly bent. However, there's no rule that necessarily says the steel HAS to be on the inside. For example, you can mount a hollow pole, then fill it with very runny concrete grout to give it compressive strength and minimize things like buckling.
Going out on a limb here, to what extent would the accidentally superior cement in that area lead to the establishment of an empire? All those structures would be stronger than the other guys, which would have to count for something. I find it interesting to think that they dominated the time in part due to naturally occurring ash and such.
Makes you wonder what subtle things in the modern world lead to success - the US in particular. Are we strong due to our laws? Our constitution? The wide open land full of resources? Peoples attitudes toward any number of things? The diversity? Who knows, certainly some of those things could be as subtle as a different composition of volcanic ash.
I thought I recalled the use of hollow pots in the aggregate, but I couldn't find a cite for that claim so I omitted it. It was an ingenious idea, though.
Yeah, and the pyramids were impossible to build, too. And thermite does not exist, and liquid nitrogen cannot keep things cold, and steel is a perfect conductor of heat so it would be impossible anyway. Right?
Sarcasm aside:
Why must it be 5x10x40 feet?
And why must it be welded, anyway? There are lots of other ways to join steel.
Have to be? You sound mighty certain of yourself.
Rather, it's just that these shapes constitute tend a more efficient use (in terms of strength vs. weight) of material. Transportability is way down on the list: You can almost always get a bigger truck/crane/whatever.
In broader strokes, just because one thing is easier to transport or place, does not mean that some other thing is impossible to manage. (Give me a lever and a place to stand....)
And in one specific case: PiRod towers are made from solid (not tubular) round steel bars, with off-the-shelf self-supporting designs going up as high as 600 feet.
(And to be clear: Building big things out of solid steel is a often stupid idea. But being a stupid idea does not mean that it cannot be done: People do stupid, absurdly difficult things all of the time, sometimes even quite successfully.)
Kid-proof tablet..
Actually, there is a school of thought that speculates that the US is in the position it finds itself in precisely because of the land we found ourselves living on. But the Russian Federation / USSR has more of just about everything in the way of natural resources than the north american continent. So its an interesting speculation, but still up for debate.
Sig Battery depleted. Reverting to safe mode.
It's our huge tracts of land.
In 'Economic History' we were taught that the widespread use of cheap barbed wire (to tame the prairies) was what gave the USA its biggest boost. And when that wire came to Europe, it changed WW1 from a fast war of cavalry charges to a slow war of trench attrition, and ruined several other empires as a result.
Posting to undo
A new discovery? I've been reading about this for at least 20 years and nothing has come from it so far. Hopefully these researchers have now solved the technical problems in producing it.
According to this Roman's didn't use rebar.
http://en.wikipedia.org/wiki/Roman_concrete
However I was in Rome a few years back and it sure seemed like they did. Perhaps it was that they didn't use concrete like we do today, i.e. entire poured structures. To increase the stability and structural strength of stone blocks iron bars were used to connect them, or at least they did in the Colosseum. Roman concrete was also used, but not as a stand alone product in the most part, but rather in conjunction with stone blocks, and bricks.
Also the primary problem with the iron bars being used, was that it was incredibly expensive at the time (which perhaps why not widely used), and looters would dig out the iron rods (destroying/ruining(literally!) the structure to sell them.
So while not rebar in totally the same sense as we use it today, it was used by Romans. You could also examine where it was dug out, and where they only got partially through, but exposed the iron to view.