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.'"
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.
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)
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 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.
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: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.)
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, 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.
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.
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, 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, 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, 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.