ôRoman seawater concrete holds the secret to cutting carbon emissionsö

[racookpe1978]

Came across Catastrophic Anthropogenic Global Warming (enviro-themed press-release-by-government-sponsored CAGW research) this morning:

“Roman seawater concrete holds the secret to cutting carbon emissions”

he chemical secrets of a concrete Roman breakwater that has spent the last 2,000 years submerged in the Mediterranean Sea have been uncovered by an international team of researchers led by Paulo Monteiro of the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), a professor of civil and environmental engineering at the University of California, Berkeley.
Analysis of samples provided by team member Marie Jackson pinpointed why the best Roman concrete was superior to most modern concrete in durability, why its manufacture was less environmentally damaging – and how these improvements could be adopted in the modern world.
“It’s not that modern concrete isn’t good – it’s so good we use 19 billion tons of it a year,” says Monteiro. “The problem is that manufacturing Portland cement accounts for seven percent of the carbon dioxide that industry puts into the air.”
Portland cement is the source of the “glue” that holds most modern concrete together. But making it releases carbon from burning fuel, needed to heat a mix of limestone and clays to 1,450 degrees Celsius (2,642 degrees Fahrenheit) – and from the heated limestone (calcium carbonate) itself. Monteiro’s team found that the Romans, by contrast, used much less lime and made it from limestone baked at 900˚ C (1,652˚ F) or lower, requiring far less fuel that Portland cement.
Cutting greenhouse gas emissions is one powerful incentive for finding a better way to provide the concrete the world needs; another is the need for stronger, longer-lasting buildings, bridges, and other structures.
“In the middle 20th century, concrete structures were designed to last 50 years, and a lot of them are on borrowed time,” Monteiro says. “Now we design buildings to last 100 to 120 years.” Yet Roman harbor installations have survived 2,000 years of chemical attack and wave action underwater. . .

http://phys.org/news/2013-06-roman-seawater-concrete-secret-carbon.html

OK. I'll belief their research. Maybe.

For the structural specialists amongst us, two relevant questions;

Are today's concrete structures "living on borrowed time" as she so breathlessly writes/ Or is the potential failures due to rust, rebar exposure and corrosion, and failure to maintain the steel paint and protection on systems outside of the concrete itself on state-maintained bridges and roadways and dams and locks?

Was Roman concrete so good that we should copy it chemically?

 

[briancpotter]

Original paper is here, if anyone has institution-access:

http://onlinelibrary.wiley.com/doi/...sCustomisedMessage=&userIsAuthenticated=false

I was under the impression age-related failure of concrete was almost entirely due to rebar corrosion.

Brian C Potter, PE

http://simplesupports.wordpress.com

 

[Archie264]

The answer to both of your questions is "no".

I've seen cores taken out of 50 year old buildings where the reinforcing steel is as perfect and sparkly as the day it was made.

If Roman concrete was superior to what is currently available we would be using it. This isn't playtime where we intentionally use sub-optimal products.

The author found what she set out to find, which is entirely consistent with the findings of other global warmist pseudo- scientists.

 

[Archie264]

Whoops, Brian, our posts crossed in the mail. I was responding to the original post.

 

[MikeHalloran]

John V. Lindsay fired all of New York City's bridge painters in response to a pertubation in the city's perpetual budget crisis. Somehow that became the new standard for bridge maintenance in a lot of cities, catalyzed by the now familiar political fantasy assertion that it's cheaper to replace a bridge than to keep painting it, still echoed regularly by empty heads.

At the same time, politicos in quasi-Northern cities continue to respond to the slightest threat of snow accumulation with ever-increasing deluges of salt, and some even worse stuff.

The construction and protection systems being specified today have not kept up with such changes in the infrastucture environment.

Our structures are doomed.



Mike Halloran
Pembroke Pines, FL, USA

 

[TenPenny]

I'm curious about what exactly the lifespan of concrete that has been under seawater for 2000 years has to do with concrete structures in the open air.

 

[dhengr]

Maybe we should be salting our concrete structures more frequently, to mimic the Mediterranean water salt content. But, not too much or you’ll give the structure high whatever pressure. And, we should force all passers-buy to wave vigorously, so that there is wave action of some sort.

 

[cvg]

the primary component of the roman version is volcanic ash (natural pozzolan) which is similar to the fly ash commonly used in most concrete. however, short of importing italian pozzolan from Pompei at huge monetary and energy consumption cost, most engineers specify more locally available fly ash which is a by product of coal burning power plants. This also serves to utilize a waste product which otherwise would become a landfill and reduces the energy consumption required to transport ash longer distances. While fly ash increases strength of concrete and water resistance, it generally slows down the rate of strength gain. So for many applications (such as buildings and bridges), it would require either additional cement content or finer ground cement to get the higher early strength required to keep projects on schedule. This of course requires more energy consumption either way.

 

[rb1957]

"and what have the romans done for us ?" ...

Quando Omni Flunkus Moritati

 

[TXStructural]

Concrete submerged for 2000 years has not been subject to carbonation as it would be in CO2-laden air, lending to its durability. The fineness of Roman concrete was undoubtedly a great deal lower than today's materials, lending to an ongoing strength gain. Roman concrete was very weak in tension, and we could certainly build very robust structures using the kind of proportioning that unreinforced structures require, but at a much greater environmental cost. I also imagine that modern combustion and heating processes are quite a bit more efficient than those used by the Romans.

The Romans also didn't have electricity, or cars, or TVs, or plastics, so if we are looking to cut emissions...

Apple v oranges

 

[cvg]

adding on to Tex's post, submerging concrete in water is an ideal method of curing, especially for a concrete mix high in natural pozzolan. It provides adequate water to allow hydration to continue for years, which incidentally was required due to the nature of the natural pozzolan. But, even with a prolonged curing period, measured compressive strength of roman concrete after 2000 years is only approaching 2800 psi which is far lower than the typical long term strength of structural concrete used today which would probably be at least double that.

 

[charliealphabravo]

"and what have the romans done for us ?" ...

uhhhh....the aqueducts???

 

[IDS]

So where in the passage quoted in the OP was there any mention on "Catastrophic Anthropogenic Global Warming"? It was just a typical bit of inaccurate media hype about some research which may or may not have been worthwhile.

Concrete is responsible for a significant proportion of CO2 emissions. These emissions can be and should be reduced. Whether we have much to learn from roman practices, I doubt.

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/