Ancient Roman Concrete Is About To Revolutionize Modern Architecture 322
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.'"
Prior art (Score:5, Interesting)
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"...?
Re:Prior art (Score:5, Insightful)
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"...?
People are amazed by this new discovery and yet legality was the first thought here.
I know you were somewhat joking here, but this is exactly why we can't have nice things. Too many damn laws stand in the way of true innovation anymore. It will be our demise.
Re:Prior art (Score:5, Insightful)
> I know you were somewhat joking here, but this is exactly why we can't have nice things.
> Too many damn laws stand in the way of true innovation anymore. It will be our demise.
And I suspect that some (specifically, the owners of that "Intellectual Property") peoples' real attitude is that they will be on top of you and me as we all sink, and the sinking will stop while they're still above water. Whether or not you and I are above water will not be relevant, as long there are enough left to do the necessary work for a pittance.
Re:Prior art (Score:4, Informative)
It won't be worth patenting, if they even found anything new recipe-wise. Most concrete is steel-reinforced, and most of the failure you see is the rebar corroding. It's not hard to imagine how a lime-volcanic ash mixture would make this unsuitable for steel-reinforced concrete.
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Even if so, it could be worth building things without rebar, imitating this recipe, if you want something that'll stand for thousands of years instead of 50. Sure, it may not have the same structural strengths to begin with, but it'll keep its strength much longer.
Good for art and such, or any building meant to be impressive or to be used for a long time.
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Re:Prior art (Score:5, Informative)
The problem is that it's the rebar itself that often destroys the structure. Concrete is porous, and so water finds it's way into the structure and gradually corrodes the rebar. The problem is that rust (iron+oxygen) is considerably larger than the original iron, and since concrete can't stretch to accommadate the expansion it eventually gets torn apart.
Re:Prior art (Score:4, Interesting)
Stainless steel isn't rust proof - it just "stains less" (and is a *lot* more expensive, something like 10-20x IRC). And once rust does get established it still spreads pretty quickly. And sure a protective coating helps but still isn't fool proof. The biggest issue though is simply that in most situations modern concrete will have degraded to the point that it really needs to be replaced anyway before the rebar expands enough to crack it, so there just isn't really any point in adding expensive protections.
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Anyone with a boat kept in saltwater can attest to the fact that stainless rusts, and rather quickly. Saltwater is hard on everything except the things evolved to live in it.
Re:Prior art (Score:5, Informative)
Speaking as somebody whose family has lived on the ocean for over 18 years, marine-grade stainlees is pretty near impervious to seawater. You need to check it periodically, of course, but if you use the right stuff (which is closer to the "20x cost of mild steel" end of the range) it will happily endure for a very long time without even significant discoloration. Of course, it helps there the boat also has zincs and that we're careful about dissimilar metals and so forth. Nonetheless, a really good grade of stainless (one way to tell is to check with a powerful magnet; good stainless is not noticeably magnetic) is able to endure seawater much better than you imply. You just can't be cheap about it... which makes it impractical as a building material in most cases.
Re:Prior art (Score:4, Interesting)
stainless steel is not 100% immune to such problems, and has much lower tensile strength than normal steel, and I'm unaware of any protective coating that would be up to the job.
Re:Prior art (Score:4, Insightful)
Fiberglass reinforced plastic hulls, the most ubiquitous type, commonly experience what are called blisters. Even the epoxies (the plastic part) are not totally impervious to salt water and over the years, it seeps in and can cause a chemical reaction -- this expands and leaves a blister. Examples: https://www.google.com/images?q=fiberglass+blisters [google.com]
You have to grind them away, fill with new epoxy, fair your work, and then you can put on new bottom paint. Every aspect is toxic.
Other kinds of plastic degrade as well. For example, it only takes a couple years for 5 gal plastic pail to become brittle -- I had to replace a couple this year that had only seen three seasons holding shrimp and crabs because the rims shattered just with light handling.
It really doesn't matter what you put in or near sea water -- it will destroy it. Which makes this Roman Concrete pretty astounding.
Re:Prior art (Score:5, Informative)
Actually atom size is only very loosley related to atomic weight - size does increase as you move down the periodic table in a single column (more electron shells), but it actually shrinks as you move to the right (tighter bonding between electrons and the nucleus). Basically the discrepancy is because atomic mass is determined almost entirely by the nucleus, which is several orders of magnitude smaller than the entire atom. Size on the other hand is determined by the arrangement of the electron cloud.
For a quick visual reference: http://www.crystalmaker.com/support/tutorials/crystalmaker/atomicradii/ [crystalmaker.com]
Notice that a lithium atom, with an atomic mass of only 7, is actually about the same size as bismuth, which has an atomic mass of 209
And the basic fact is that the oxide can't possibly be the same size as the original material. Common rust has the chemical formula Fe2O3, which means that where you used to have only two iron atoms, you now have two iron atoms PLUS three oxygen atoms. But you are right that the basic strategy is to prevent flaking, if we could somehow "convince" the oxide to form hematite crystals instead of flaking away corrosion would be a non-issue. That's why highly reactive aluminum appears to be so stable, the oxide readily forms a thin crystaline layer bonded to the metal which prevents further oxidation (basically corundum, the base gemstone of rubies and saphires). Disrupt the oxide layer and the aluminum will *very* rapidly rust away, as in you can actually see a beam "dissolving" in front of you - that's why they don't allow mercury thermometers on airplanes, mercury is one such disrupting agent and a spill could cause the aircraft to come apart in the air.
Re:Prior art (Score:5, Insightful)
For all the bashing on Wikipedia I remember seeing several studies that showed that, excepting controversial topics (which can suffer from orchestrated edit wars and astroturfing), the accuracy was generally on-par or better than The Encyclopedia Britanica and other "gold standard" sources. It may not always be completely accurate and up to date, but will typically be as reliable as any other single reference source, and the information will often far more detailed and accessible than most.
So how about instead of bashing one of the most reliable and comprehensive encyclopedias in the world, you instead go ahead and update the page that links to the obsolete periodic table image. You don't even have to understand the markup, just search for the link and make the minor tweak. Or do you really prefer to be one of the gawking bystanders?
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Seems fairly simple to me. Find the average mineral ratio of this ash, pour together readily-available types of material to get the same mineral ratio, see if that works. If it does, yay. If it doesn't, grind it up. If that doesn't work, find out of there's small structures in the ash that are important. If the latter, we could still use the recipe for special projects by using real volcanic ash.
Re:Prior art (Score:5, Informative)
Turns out its not the ash that mattered.
Its just the composition of the particular variety of ash they had on hand. Volcanic ash differs in various volcanic regions. Further, seawater was also key. You don't find much of that in the middle of continents.
This wasn't ancient knowledge at work at all. It was simply an accident of geography.
Is it really any different from the fact that availability of raw materials in any region is an accident of geography?
If you read TFA you will see that:
A) the Romans were well aware which ashes were the best for this purpose. Vitruvius and Pliny wrote about it. It is not as if they were mystified why this hydraulic cement was turning out so well. Sure they didn't understand the chemistry, but they tried many ashes and knew the ones that had special properties.
B) The researchers found this concrete in 11 harbors around the Mediterranean. This means the Roman were exporting their special ash to where it was needed for harbor construction.
Sounds like ancient knowledge to me. (Otherwise you are going to have to hold that none of the material production skills before modern times were really ancient knowledge.)
Re:Prior art (Score:5, Insightful)
The harder part may be finding enough suitable sources of volcanic ash that can be mined, and not all ash has the same mineral ratios and such. That would still limit its use unless there's some way to make a decent enough man-made equivalent that's better than the Portland formula.
And right there you've put your finger on both the source of the mystery and why this won't work everywhere.
In ancient Rome they didn't have the huge reduction furnaces used in the creation of Portland Cement. All they had was the raw materials found laying around or easily mined. Living in a volcanic region near the sea they had both in abundance.
In other areas conquered by Rome they never found the same mix of volcanic materials, lime, and seawater, and the structures they built there did not hold up as well. The aluminum-rich pozzolan ash isn't exactly something you find in the British isles or France. And away from the sea, any available water would be used. Its entirely possible the Romans had no no idea that sea water was essential to this mixture.
The whole thing was an accident of geography, and apparently one which no one cared to look into too closely, or those that did were unable to replicate due to raw material availability, because analysis of the composition of roman cement was well withing the scientific capabilities of even the 1800s and probably even the 1600s.
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I hear ya, but if I'm an artist that is going to build a 5000-year building, I'll go with big blocks of attractive stone. This stuff would likely be super-pricey.
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The romans did it on a pretty big scale, as far as I understand. So industrializing it with current technology would probably be fairly easy. There's no real reason it should be pricey after it catches on, if it does so at all.
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If the ingredients are more expensive, the cement will be more expensive. For instance, the Roman variety calls for more aluminum and less sand. They also mention unspecified "minerals" as being present in Roman cement that are not normally present in Portland cement.
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They could electrolyze bauxite in 100 AD?
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The real issue is that we simply don't want or need anything to last for a thousand years anymore. It's just not effective: buildings, roads, and other structures are usually replaced well before that, simply because of shifting demographics and economy.
Re:Prior art (Score:5, Interesting)
Steel reinforcement would negate the longevity of Roman concrete anyway. The rebar will eventually rust out and crack the concrete as it expands. That's fine if your concrete won't last nearly as long as the rebar anyway, but with Roman concrete the rebar would completely rust away while the concrete itself was still just fine.
There are other benefits though, mainly the reduced carbon footprint of production, and the near-total immunity to spalling which all modern concretes suffer from.
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Perhaps a really clever person could come up with a way of coating the rebar in a waterproof or non-reactive coating. Maybe it's not cost effective, but it seems like a simple problem to solve.
Re:Prior art (Score:5, Interesting)
The biggest problem in todays concrete production is cost effectiveness. We can produce hundreds of concretes with widely varying properties. We can mix concretes with negligible carbon footprint or extreme durability or very steep viscoelasticity, but pumping tons of these into a foundation would cost more than simply using pure steel for all of it.
Source: I've just passed a polymer physics course, and the professors primary research area is concretes.
captcha: unfold
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But still has extremely low tensile strength, which is what they're after when adding rebar to concrete.
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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.
Supposing that all their study concludes that reinforced concrete is essential in some cases, does that mean Roman concrete is never to be preferred? Slabs of parking lot, sidewalk, and
Prestressed concrete performs better under tension (Score:5, Informative)
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 [hhttps] 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 [google.com].
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 [wikipedia.org], 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.
Corrupted link was corrupt. (Score:2)
Prestressed concrete [wikipedia.org]
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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), reinforc
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I am fairly certain it depends on the arch/dome curvature.
Good point. I should have said that a dome can be designed so that the stresses are primarily compressive. My point was that otherwise they wouldn't have been able to build the Pantheon with unreinforced concrete. I'm always amazed at how they managed to figure out good design rules without any mathematical stress analysis. Obviously they managed, though it may have involved a few things falling down or at least having to be patched up post-construction (not that that doesn't happen nowadays). Perhaps it al
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I'm not pooh-poohing their efforts, I'm just skeptical that lime-ash concrete as used by the Romans will lead to breakthroughs. I think their work is very interesting, and any kind of discovery like this lets us better-understand our world. It's just that if you make concrete much more expensive, other materials start to make more sense. For instance, if I'm making a big breakwater, eventually a giant hunk of stone will be more economical than concrete. The scientists involved seem to be chasing the carbon
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why is it necessary for concrete to be reinforced
Because straight concrete has good strength in compression, but very little in tension (and hence little in bending). If you use unreinforced concrete you're limited to structures where almost all the stresses are in compression, like arches and short columns.
Comment removed (Score:5, Interesting)
Re:Prior art (Score:5, Funny)
The invention of the modern safety elevator revolutionized construction in the major cities of the world. Prior to them becoming affordable almost no buildings in New York City were higher than six stories, and the top floors were always the cheapest. It made no financial sense to build higher, no one wanted to carry groceries up to the 27th floor.
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Roman works relied strictly on compression (arches and domes are good examples). There is no doubt that compression works can be more durable than tension structures because by the nature of the beast they require much more material to build. Because of this, they have much more material to wear off (redundancy) and so they can better resist the passage of time (and erosion).
Of course, as in everything, there are tradeoffs. One of them being the shear mass of materials required for construction. Engineerin
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Yes but did build modern scale coliseums. Some of those are still being used today.
Re:Prior art (Score:5, Funny)
In regards to rebar necessity, it is in order to achieve sufficient tensile strength in lesser thicknesses of concrete pours. It is absolutely possible to build a bridge with no rebar, just make the bridge one big slab that extends from the road to the river bed.
Ummm, I believe that would be called a dam.
First to file (Score:5, Interesting)
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Yes, but you still can't patent something that's widespread public knowledge.
Which, of course, this isn't. It's been long since forgotten.
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What can be patented isn't the invention, but the process for making it en masse for modern needs. The quantity involved will far exceed the Roman usage.
The complications is that most volcanic rock today is protected by national or regional parks (partly to protect people from being too close for a long time). Etna, Vesuvius, Hawaii, Iceland - many of those aren't going to just let corporations come in with the same giant trucks they use for coal mines today and rip away 3/4s of the mountainside or lava f
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This article doesn't talk about it, but the volcanic ash (AOL Keyword: pozzolan ash) can be found in deposits all over the world.
It's already mined commercially and it will be trivial to increase that mining capacity in locations that are far away from anywhere environmentally sensitive.
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Thanks for the clarification. :)
Re:Prior art (Score:4, Interesting)
Honestly, I would have absolutely NO problem with granting someone a patent if they were able to recreate Roman concrete. What's twenty years compared to the value of concrete that can survive 2000 years of coast-water abuse? This is in fact *exactly* the sort of thing patents were designed for - to promote the development of technologies for the good of mankind. What difference does it really make whether the technology is completely new or something that had been lost to the ages?
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So if I reverse engineer a product that is not patented and relies on trade secrets to function I can get a patent as well? That's effectively what was done here, with the addition of the secret being lost.
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Sure, why not? If they have neither published or patented the invention then it doesn't exist as far as the rest of the world is concerned. The original creator decided they preffered the indefinite advantage of trade secret versus the short-term monopoly of patents in exchange for sharing the technology. So basically you have created something that's new to the rest of the world, and shared it with everyone in exchange for a limited monopoly. In fact I'm willing to bet you could even sue the original in
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Sure they can copy it, but they can't patent it. Patents are for *inventions*.
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Tell that to the Patent Office.
But basically it's a pretty contrived example - if reverse engineering is likely to be substantially easier than inventing it from scratch then a company has good incentive to patent rather than rely on trade secrets. And if it's not easier, well then you've worked just as hard and are willing to share your knowledge with the world, so why shouldn't you get the benefit? Even then probably the only reason to reverse engineer rather than reinvent would be for some sort of inte
Re:Prior art (Score:4, Informative)
AFAIK, yes, it can be patented. And that's perfectly OK. Roman concrete wasn't a useful art, it was a lost art. At least under the official theory of American patent law, patents exist to promote advances in useful arts, not to merely grant a monopoly over some abstract artistic right. "Prior Art" isn't just something that EXISTED... it's something that existed, with documentation that would have allowed somebody ELSE to re-create it. Without that documentation, Roman Concrete was little more than a mere idea... maybe a half-step better since it was more like a "proof of concept", but the fact that substantial effort was required to re-discover and document it IMHO does make it patent-worthy.
Now, if Cemex (or some other company that makes concrete) gets sued for infringement 14 years from now, and shows up in court with some ancient, long-lost and recently-rediscovered Greco-Roman document with the formula, they'd have a solid case for overturning a modern patent on it.
Before somebody brings up "first to file", I should point out that if I invent and document something, but someone else beats me to the patent office, I might not be able to get the patent transferred to ME, but I can certainly show up late and spoil the party for THEM. In a way, "First to File" opens the door to trolling trolls... if you invent something, but don't necessarily think it's worth patenting (or have the resources to secure that patent), you can abundantly document it (possibly via digital notarization), then just sit on your notes. If somebody ELSE gets a patent, you can demand that they give you a cut of the royalties they collect, and threaten to go public with your own prior art and spoil their party (after they've spent hundreds of thousands of dollars securing the patent) if they don't.
Re:Prior art (Score:5, Informative)
If you really want to check facts, the Vatican was first recognized as a separate nation in 1929 a.d. by the Lateran Treaty, signed by representitives of the then current pope on one hand and Benito Mussolini on the other. 1929 is just a tad later than the end of the Roman empire.* Maybe you are thinking of 'the' Holy See,** or some of the Papal Estates that went back to at least Medieval times.
* Watch someone post "citation needed".
**Technically, any Bishop's diocese is a See, and presumably at least some Bishops in some eras have been not particularly unholy, so what the Pope, as Bishop of Rome, has, is merely a holy see, even though a lot of lay people seem to use the term like he has a lock on it.
Re:Prior art (Score:5, Interesting)
Christianity was part of the cause of the downfall.
So sayeth some (e.g. Gibbons [wikipedia.org]), but I think that's more about the agenda of the writer/historian than a dispassionate look at the facts. I'd argue the Crisis of the Third Century [wikipedia.org] was the real beginning of the end (and started the path to the early middle ages) , yet it happened before Christianity became the official religion of the empire in the fourth century.
Re:Prior art (Score:5, Insightful)
Other things contributed to the collapse such increased border invasions from Central Asia tribes (perhaps due to Chinese expansion forcing these tribes westward). Whatever it was - the collapse of the Roman Empire was not due to the rise of Christianity.
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Re:Prior art (Score:5, Interesting)
Total bullcrap.
After the Christianizing of Rome, much classical knowledge still remained available. Literacy was high and papyrus from Egypt was available for writing. The library at Alexandria was restocked several times after fires with works held in private collections. And the families of Germanic invaders actually had their children educated by Romans and many old Roman cities kept their Roman character.
Then suddenly old Roman cities failed and were quickly covered by a layer of soil called the "Younger fill". Literacy declined and papyrus was no longer available because trade with Egypt was no longer possible as the Mediterranean was controlled by pirates. Many classical works were lost and the library at Alexandria could not be restocked. Christian monks were forced to write on animal skins instead of paper.
This all began long after Christianity -- around the middle of the 7th century. I'll leave it to you to figure out what other events of the 7th century might be responsible.
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Re:Prior art (Score:4, Informative)
The medieval warming period is well known peaking from the 11th through the 13th C. The plagues are well documented from 200-700AD and from 1350-1700. The plots of land available for farming are also known from both tax records as well as botanical records. (How far up mountains crops are being grown.) Keep in mind that this describes a gradual cycle. There is no hard and fast date where it was warm until a particular date (say 199AD) and then cold from 200AD-700AD and then warm again.
A quick search shows a list of major plagues: http://en.wikipedia.org/wiki/List_of_epidemics [wikipedia.org] . Generally in cold and wet periods plagues happened every generation.
Re:Prior art (Score:5, Insightful)
Christianity was part of the cause of the downfall.
Another argument against that idea is that while the Western Empire fell in the 5th century, the Eastern Empire, which was just as Christian, continued for another 1000 years.
De Architectura (Score:5, Insightful)
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 [wikipedia.org]
Perhaps the story is confusing the known composition with some mechanism that the new study discovered.
Re:De Architectura (Score:5, Interesting)
Re:De Architectura (Score:5, Interesting)
So, no, this isn't some revolutionary new discovery. Those claiming so are either ignorant of previous art - and that's *recent* previous art - or are deliberately trying to build up their own claims.
Or, maybe, just maybe, the Slashdot summary is merely quoting the first part of the press release that explains previously known information, but the Slashdot summary doesn't contain the actual details of the new findings, which describe some previously unknown aspects of the chemistry involved... some of which appear to be essential to the structural properties observed.
But, oops... for that you'd have to RTFA.
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Re:De Architectura (Score:4, Informative)
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?
Umm, care to RTFA? From the press release:
Descriptions of volcanic ash have survived from ancient times. First Vitruvius, an engineer for the Emperor Augustus, and later Pliny the Elder recorded that the best maritime concrete was made with ash from volcanic regions of the Gulf of Naples ... especially from sites near todayâ(TM)s seaside town of Pozzuoli.
I'm not sure exactly all that is new here, but in the press release you can read about the role of aluminum, the effect of lower temperatures in the manufacturing process, the production of certain end products in curing that are not found in modern concrete (due to the things already mentioned), etc.
Perhaps the story is confusing the known composition with some mechanism that the new study discovered.
Or perhaps you just didn't read the link to find out that's exactly what the press release is about.
Roman concrete produces a significantly different compound [from modern concrete], with added aluminum and less silicon. The resulting calcium-aluminum-silicate-hydrate (C-A-S-H) is an exceptionally stable binder.... 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.
Etc.
(The article also, by the way, seems to be about streamlining manufacturing to produce a better product with less energy and heat, thereby reducing carbon emissions, etc.)
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As is common, the university press release (and the news story that cribs from it) is considerably over the top compared to the actual publications (and the actual findings). The research is interesting, but not some kind of groundbreaking discovery of Roman marine concrete, which is of course already well known. What it's actually doing is detailed investigation into the chemical properties of the concrete and how it's formed, in order to better understand the particular material-science aspects of this fo
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What a bunch of crap! Yes, you're absolutely correct: this is all (literally) ancient history.
http://en.wikipedia.org/wiki/Roman_concrete [wikipedia.org]
"Vitruvius, writing around 25 BC in his Ten Books on Architecture, distinguished types of aggregate appropriate for the preparation of lime mortars. For structural mortars, he recommended pozzolana, which were volcanic sands from the sandlike beds of Pozzuoli brownish-yellow-gray in color near Naples and reddish-brown at Rome. Vitruvius specifies a ratio of 1 part lime t
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Re:De Architectura (Score:5, Funny)
Didn't Vitruvius describe it in his De Architectura, written about 15 BC?
According to the terms of the Mickius Mousius copyright extension act, that means it'll soon enter the public domain.
WWARS (What Would Ayn Rand Say) (Score:5, Funny)
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WWARS (What Would Ayn Rand Say)
"Money should be restricted to your social betters."
Also, she'd probably write a masturbation fantasy for rich people, about how much their social inferiors would suffer after a Rapture of the Rich.
Bloody Romans! (Score:5, Funny)
Re:Bloody Romans! (Score:5, Funny)
On the down side, they had to change their concrete marketing slogan from "It keeps the Germans out" to "It keeps the seawater out".
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They taught grammar to barbarians; unfortunately English discarded most of it.
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As your post shows, you clearly don't.
Re:Bloody Romans! (Score:5, Insightful)
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They taught us why it is not a good idea to flavour wine with lead?
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I think the Iranians have the beat on wine beat by a couple hundred years at least
Re:Bloody Romans! (Score:5, Informative)
pasta.
The Romans ate bread, not pasta. Noodles were invented in China, and didn't reach Europe until the late middle ages. The first record of pasta being made in Italy was in 1154.
Re:Bloody Romans! (Score:4, Funny)
pasta.
The Romans ate bread, not pasta. Noodles were invented in China, and didn't reach Europe until the late middle ages. The first record of pasta being made in Italy was in 1154.
So Pastafarianism is an Oriental religion?
Re: (Score:2)
... that doesn't change that apparently we haven't even tried to figure out their concrete before. Even though it's just about everywhere and we very well knew it was superior to what we had access to. Who's the lazy bum now, eh?
As mentioned in a previous thread, we haven't tried to figure out their concrete because we haven't had to... they left us the recipe, and it's been discussed through the centuries by anyone remotely interested in the stuff.
It just doesn't have all the properties (structural, cost and availability) that are desirable for most modern construction. Makes good statues / fake rocks though.
Well there's a news flash. (Score:5, Funny)
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?
Duh (Score:3)
Cement is not concrete. Concrete is made of cement plus aggregate.
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Opus caementitium (Score:3, Informative)
Anything changed in 3 decades - will anything change in the near future in a billion $ industry?
BOHA!
Revolutionize or "more eco-friendly"? (Score:5, Informative)
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Indeed, this is nothing new.
Most concrete ready-mix suppliers cut their portland cement by around 20% with Fly Ash , another pozzolan. It makes better, cheaper concrete. This is well known. However, the more Portland Cement you replace with pozzolans, the slower the cure.
The markets skew towards high-portland content concrete is largely dictated by the desire to strip forms as soon as possible. With portland, forms are striped in 24 hours. WIth high pozzolan content concrete, the forms often need to be in p
NEWSFLASH (Score:3, Interesting)
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]
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Yup - obviously the Roman stuff has essentially had the benefit of selection applied. I wouldn't be surprised if the Romans had a bunch of ways of making cement, but the stuff we notice is the stuff that is still around.
That said, nothing wrong with learning from it all. We don't really have any modern materials that have gone through 2000-year stability tests under real-world conditions. Stuff that we fortuitously have at hand to study could turn up other useful finds.
Re:NEWSFLASH (Score:4, Insightful)
People discovered this in 86 it seems. (Score:2, Informative)
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
Re:People discovered this in 86 it seems. (Score:5, Interesting)
Yes this article is garbage IMO. Pozzolans are the basis of concrete. That's what concrete powder is, an artificially produced pozzolan. Fly Ash is also a Pozzolan, we've been using in PCC for decades. Volcanic ash is also a Pozzolan, and in a sense it is "green" to use volcanic ash instead of modern cement powder because you don't have the input energy to make the cement powder. But Volcanic fly ash is NOT an unlimited supply and mining and transporting it may use just as much energy as cement powder.
Second, Modern Portland Cement does NOT deteriorate after 50 years. Properly placed concrete has no known lifespan. (if concrete only lasted 50 years there would be a LOT of buildings failing every year) What does fail, as has been noted, is the reinforcing steel used to give the concrete tensile strength (concrete has no tensile strength) and wear and tear. There are ways around the rusting rebar that are being used, galvanized rebar, epoxy coated and stainless steel are just a few of the techniques being used to increase the lifespan of the rebar to give equal lifespan to the steel and concrete.
Finally, we can make concrete better than the Romans, we just have to use the equivalent amount of Pozzolans they were using. When the Europeans (after the dark age) tried to duplicate the Roman mix they found it far to wet to be usable, the missing knowledge was that one of the mix ingredients was all that volcanic ash which meant the amount of pozzolan in the mix was far higher and in fact comprised a significant percentage of the mix. In fact the measurements made recently have shown that modern concrete isn't using near the equivalent amount of cement powder. Stronger concrete can easily be produced by increasing the amount of cement powder, the problem is the cost that adds. We don't use concrete of that strength generally because of two reasons, cost and failure mode. Standard reinforced portland cement concrete fails in a manner that provides warning of imminent collapse, high strength reinforced concrete does not provide that warning, it fails explosively.
So in summary that is the WORST cement article I've ever read, but what can you expect from Businessweek I guess. It reads like a scam article to get someone to invest money in an idea that isn't revolutionary. Caveat Emptor.
Its the good stuff that lasts (Score:5, Insightful)
The headline focuses on the wrong thing. (Score:4, Insightful)
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.
Ancient Romans (Score:5, Funny)
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Re:Ancient Roman First Post is about to revolution (Score:4, Insightful)
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.
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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 c
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Roman concrete can't be steel-reinforced
Why?