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Ancient Roman Concrete Is About To Revolutionize Modern Architecture 322

Posted by Soulskill
from the when-in-rome dept.
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.'"
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Ancient Roman Concrete Is About To Revolutionize Modern Architecture

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  • Prior art (Score:5, Interesting)

    by advantis (622471) on Saturday June 15, 2013 @11:45AM (#44015057)

    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)

      by geekmux (1040042) on Saturday June 15, 2013 @11:53AM (#44015109)

      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)

        by dpilot (134227) on Saturday June 15, 2013 @12:03PM (#44015165) Homepage Journal

        > 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)

      by MightyYar (622222) on Saturday June 15, 2013 @12:05PM (#44015175)

      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.

      • by Dekker3D (989692)

        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.

        • by stymy (1223496)
          I'm no engineer, but why couldn't this recipe be used with rebar? Corrosion from the water that needs to be absorbed, or what?
          • Re:Prior art (Score:5, Informative)

            by Immerman (2627577) on Saturday June 15, 2013 @01:01PM (#44015503)

            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.

        • by MightyYar (622222)

          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.

          • by Dekker3D (989692)

            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.

            • by MightyYar (622222)

              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.

              • For instance, the Roman variety calls for more aluminum and less sand.

                They could electrolyze bauxite in 100 AD?

        • by Baloroth (2370816)

          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)

        by Immerman (2627577) on Saturday June 15, 2013 @01:07PM (#44015541)

        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.

        • by Nerdfest (867930)

          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)

            by Anonymous Coward on Saturday June 15, 2013 @01:38PM (#44015753)

            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

      • 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

        • by stoploss (2842505) on Saturday June 15, 2013 @01:57PM (#44015867)

          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.

          • 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

        • Re: (Score:3, Insightful)

          by MightyYar (622222)

          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

        • 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.

        • Re:Prior art (Score:5, Interesting)

          by geoskd (321194) on Saturday June 15, 2013 @02:53PM (#44016405)

          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.

          You'll notice a distinct lack of concrete roofs on roman structures. That is because: even if they were built with them (unlikely), they have long since collapsed. Concrete has very little tensile strength. In order to get tensile strength, you have to add rebar. Were a pretty fussy breed, and for some reason we like roofs. Additionally, making a floor span out of reinforced concrete is a hell of a lot cheaper than almost any alternative. The Romans used wood...

          it should also be noted that the Romans didn't build things terribly tall. a dozen or so stories was about their limit. It goes back to lack of rebar. Concrete without rebar doesn't stand up to a lateral load very well.

          Where this stuff really shines is in a salt water environment. The concrete we have today doesn't stand up to salt water punishment well at all. We don't have *any* good formulations for this application. Rebar or not, concrete in salt water has to be replaced pretty often. The roman concrete is immensely valuable if for no other use than bridges.

          • by cusco (717999) <[brian.bixby] [at] [gmail.com]> on Saturday June 15, 2013 @04:06PM (#44016959)
            It also goes back to the lack of elevators. Think about walking up to your office on the 42nd floor in the morning . . .

            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.
        • 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

    • First to file (Score:5, Interesting)

      by rsilvergun (571051) on Saturday June 15, 2013 @12:18PM (#44015253)
      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.
    • Re: (Score:3, Interesting)

      by acroyear (5882)

      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

      • by TubeSteak (669689)

        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.

    • Re:Prior art (Score:4, Interesting)

      by Immerman (2627577) on Saturday June 15, 2013 @12:55PM (#44015467)

      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?

      • by Nerdfest (867930)

        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.

        • by Immerman (2627577)

          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

          • by Nerdfest (867930)

            Sure they can copy it, but they can't patent it. Patents are for *inventions*.

            • by Immerman (2627577)

              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)

      by Miamicanes (730264) on Saturday June 15, 2013 @01:17PM (#44015587)

      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.

  • De Architectura (Score:5, Insightful)

    by the eric conspiracy (20178) on Saturday June 15, 2013 @11:56AM (#44015123)

    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)

      by Stickmaker (711280) on Saturday June 15, 2013 @12:05PM (#44015181) Homepage
      When I was working on my BSCE in the mid-Seventies I had a course on concrete additives. Pozzolanic ash was definitely mentioned. I have also seen this mentioned many other places since then, including the fact that some of the Roman concrete mixes would cure under water. 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.
      • Re:De Architectura (Score:5, Interesting)

        by AthanasiusKircher (1333179) on Saturday June 15, 2013 @01:04PM (#44015527)

        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.

    • by Jmc23 (2353706)
      Natural builders also discuss it all the time. It's also discussed in old ceramic texts, ~1800s. Probably the only actual new knowledge here is the role aluminum plays in the structure.
    • Re:De Architectura (Score:4, Informative)

      by AthanasiusKircher (1333179) on Saturday June 15, 2013 @12:50PM (#44015435)

      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.)

    • by Trepidity (597)

      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

    • by Toad-san (64810)

      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

    • by maestroX (1061960)
      Check the original news at http://newscenter.berkeley.edu/2013/06/04/roman-concrete/ [berkeley.edu]. The businessweek article and this summary are misleading.
    • by ebno-10db (1459097) on Saturday June 15, 2013 @03:32PM (#44016723)

      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.

  • by jabberw0k (62554) on Saturday June 15, 2013 @11:56AM (#44015127) Homepage Journal
    I plan to build my next structure with Roman Concrete and Rearden Steel...
    • Re: (Score:3, Insightful)

      by Black Parrot (19622)

      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.

  • by Sponge Bath (413667) on Saturday June 15, 2013 @12:03PM (#44015161)
    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?
  • by interval1066 (668936) on Saturday June 15, 2013 @12:20PM (#44015265) Homepage Journal

    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?

  • by fnj (64210) on Saturday June 15, 2013 @12:23PM (#44015285)

    Cement is not concrete. Concrete is made of cement plus aggregate.

  • Opus caementitium (Score:3, Informative)

    by no-body (127863) on Saturday June 15, 2013 @12:27PM (#44015299)
    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!
  • by tijnbraun (226978) on Saturday June 15, 2013 @12:28PM (#44015309)
    From http://newscenter.berkeley.edu/2013/06/04/roman-concrete/ [berkeley.edu] 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.”
    • by taharvey (625577)

      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)

    by somepunk (720296) on Saturday June 15, 2013 @12:34PM (#44015345) Homepage

    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]

    • by Rich0 (548339)

      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.

  • by Anonymous Coward

    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

    • by rahvin112 (446269) on Saturday June 15, 2013 @02:50PM (#44016371)

      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.

  • by starkadder (819862) on Saturday June 15, 2013 @02:15PM (#44016037)
    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.
  • by theguyfromsaturn (802938) on Saturday June 15, 2013 @04:31PM (#44017097)

    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.

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