Ancient Roman Concrete Is About To Revolutionize Modern Architecture

schwit1 sends this news from Businesweek: "After 2,000 years, a long-lost secret behind the creation of one of the world's most durable man-made creations ever — Roman concrete — has finally been discovered by an international team of scientists, and it may have a significant impact on how we build cities of the future. Researchers have analyzed 11 harbors in the Mediterranean basin where, in many cases, 2,000-year-old (and sometimes older) headwaters constructed out of Roman concrete stand perfectly intact despite constant pounding by the sea. The most common blend of modern concrete, known as Portland cement, a formulation in use for nearly 200 years, can't come close to matching that track record. In seawater, it has a service life of less than 50 years. After that, it begins to erode. The secret to Roman concrete lies in its unique mineral formulation and production technique. As the researchers explain in a press release outlining their findings, 'The Romans made concrete by mixing lime and volcanic rock. For underwater structures, lime and volcanic ash were mixed to form mortar, and this mortar and volcanic tuff were packed into wooden forms. The seawater instantly triggered a hot chemical reaction. The lime was hydrated — incorporating water molecules into its structure — and reacted with the ash to cement the whole mixture together.'"

Comments

Prior art

[advantis]

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

[acroyear]

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 flows to get the stuff.

Re:Prior art

[Immerman]

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?

Re:Prior art

[Immerman]

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.

Re:Prior art

[Anonymous Coward]

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

Re:Prior art

[Immerman]

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.

Re:Prior art

[beelsebob]

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

[ebno-10db]

Christianity was part of the cause of the downfall.

So sayeth some (e.g. Gibbons), 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 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

[geoskd]

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.

Re:Prior art

[muon-catalyzed]

Nope, we have lost the Roman concrete precisely thanks to the Christian led purges of the 4th century. Constantine and Theodosius did it and the dark age quickly followed. They burned libraries, melted artworks dating back to the Etruscan era, history been rewritten so they are the saints now..

Re:Prior art

[Anonymous Coward]

Seawater is particularly problematic because it makes stainless steel (even 316L) corrode in cracks instead of on its surface. Gradually making initial cracks deeper and deeper, until something breaks or starts leaking, often without any visible warning. In sea water, hot-dip galvanised steel can last longer than 316L stainless steel.
It is now common practice to install electronics that keep steel structures near seawater at a pre-set voltage, relative to a few copper anodes installed in the water. About 1 Volt is enough to drastically reduce corrosion. This is especially common for steel inside concrete structures, since the concrete prevents other solutions like paint or zinc anodes.

Re:Prior art

[mc6809e]

Nope, we have lost the Roman concrete precisely thanks to the Christian led purges of the 4th century. Constantine and Theodosius did it and the dark age quickly followed. They burned libraries, melted artworks dating back to the Etruscan era, history been rewritten so they are the saints now..

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.

Re:De Architectura

[Stickmaker]

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.

First to file

[rsilvergun]

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.

NEWSFLASH

[somepunk]

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]

Re:De Architectura

[AthanasiusKircher]

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.

Re:WWARS (What Would Ayn Rand Say)

[Anonymous Coward]

There's nothing you have said that appears anywhere in the megatons of her writings. Is this the state of anti-Rand memes that filter about in your mental tribal community?

Re:People discovered this in 86 it seems.

[rahvin112]

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.