[FoRK] Concrete results

Joseph S. Barrera III joe at barrera.org
Sat Jun 15 15:08:33 PDT 2013


We could do so much better than simply bolting on a (literally) ancient 
recipe.

Why aren't the concrete manufacturers trying to innovate based on modern 
experiments instead of looking back at the ancients?

I guess not every industry yet is information-driven. Oil is, of course, 
but evidently concrete is not.

- Joe

On 6/15/2013 2:59 PM, Stephen Williams wrote:
> Finally. I heard about this discrepancy long ago.  Odd that it took so 
> long.
>
> http://www.businessweek.com/articles/2013-06-14/ancient-roman-concrete-is-about-to-revolutionize-modern-architecture 
>
> http://newscenter.lbl.gov/news-releases/2013/06/04/roman-concrete/
>
> Roman Seawater Concrete Holds the Secret to Cutting Carbon Emissions
> Berkeley Lab scientists and their colleagues have discovered the 
> properties that made ancient Roman concrete sustainable and durable
> June 04, 2013
> Paul Preuss 510-486-6249  paul_preuss at lbl.gov
>    News Release
>
> Drill core of volcanic ash-hydrated lime mortar from the ancient port 
> of Baiae in Pozzuloi Bay. Yellowish inclusions are pumice, dark stony 
> fragments are lava, gray areas consist of other volcanic crystalline 
> materials, and white spots are lime. Inset is a scanning electron 
> microscope image of the special Al-tobermorite crystals that are key 
> to the superior quality of Roman seawater concrete. (Click on image 
> for best resolution.)
>
> Drill core of volcanic ash-hydrated lime mortar from the ancient port 
> of Baiae in Pozzuloi Bay. Yellowish inclusions are pumice, dark stony 
> fragments are lava, gray areas consist of other volcanic crystalline 
> materials, and white spots are lime. Inset is a scanning electron 
> microscope image of the special Al-tobermorite crystals that are key 
> to the superior quality of Roman seawater concrete. (Click on image 
> for best resolution.)
>
> The 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 than 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.
>
> How the Romans did it
>
> 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.
>
> Pozzuoli Bay defines the northwestern region of the Bay of Naples. The 
> concrete sample examined at the Advanced Light Source by Berkeley 
> researchers, BAI.06.03, is from the ancient harbor of Baiae, one of 
> many ancient underwater sites in the region. Black lines indicate 
> caldera rims, and red areas are volcanic craters. (Click on image for 
> best resolution.)
>
> Pozzuoli Bay defines the northwestern region of the Bay of Naples. The 
> concrete sample examined at the Advanced Light Source by Berkeley 
> researchers, BAI.06.03, is from the harbor of Baiae, one of many 
> ancient underwater sites in the region. Black lines indicate caldera 
> rims, and red areas are volcanic craters. (Click on image for best 
> resolution.)
>
> 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 (Pliny died in the eruption of 
> Mt. Vesuvius that buried Pompeii), especially from sites near today’s 
> seaside town of Pozzuoli. Ash with similar mineral characteristics, 
> called pozzolan, is found in many parts of the world.
>
> Using beamlines 5.3.2.1, 5.3.2.2, 12.2.2 and 12.3.2 at Berkeley Lab’s 
> Advanced Light Source (ALS), along with other experimental facilities 
> at UC Berkeley, the King Abdullah University of Science and Technology 
> in Saudi Arabia, and the BESSY synchrotron in Germany, Monteiro and 
> his colleagues investigated maritime concrete from Pozzuoli Bay. They 
> found that Roman concrete differs from the modern kind in several 
> essential ways.
>
> 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.
>
> Finally, microscopic studies at ALS beamline 12.3.2 identified the 
> other minerals in the Roman samples. Integration of the results from 
> the various beamlines revealed the minerals’ potential applications 
> for high-performance concretes, including the encapsulation of 
> hazardous wastes.
>
> Lessons for the future
>
> Environmentally friendly modern concretes already include volcanic ash 
> or fly ash from coal-burning power plants as partial substitutes for 
> Portland cement, with good results. These blended cements also produce 
> C-A-S-H, but their long-term performance could not be determined until 
> the Monteiro team analyzed Roman concrete.
>
> Their analyses showed that the Roman recipe needed less than 10 
> percent lime by weight, made at two-thirds or less the temperature 
> required by Portland cement. Lime reacting with aluminum-rich pozzolan 
> ash and seawater formed highly stable C‑A-S-H and Al-tobermorite, 
> insuring strength and longevity. Both the materials and the way the 
> Romans used them hold lessons for the future.
>
> “For us, pozzolan is important for its practical applications,” says 
> Monteiro. “It could replace 40 percent of the world’s demand for 
> Portland cement. And there are sources of pozzolan all over the world. 
> Saudi Arabia doesn’t have any fly ash, but it has mountains of pozzolan.”
>
> Stronger, longer-lasting modern concrete, made with less fuel and less 
> release of carbon into the atmosphere, may be the legacy of a deeper 
> understanding of how the Romans made their incomparable concrete.
>
> This work was supported by King Abdullah University of Science and 
> Technology, the Loeb Classical Library Foundation at Harvard 
> University, and DOE’s Office of Science, which also supports the 
> Advanced Light Source. Samples of Roman maritime concrete were 
> provided by Marie Jackson and by the ROMACONS drilling program, 
> sponsored by CTG Italcementi of Bergamo, Italy.
>
> ###
>
> Scientific contacts: Paulo Monteiro, monteiro at ce.berkeley.edu, 
> 510-643-8251; Marie Jackson, mdjackson at berkeley.edu,  928-853-7967
>
> For more information, read the UC Berkeley press release at 
> http://newscenter.berkeley.edu/2013/06/04/roman-concrete/.
>
> “Material and elastic properties of Al-tobermorite in ancient Roman 
> seawater concrete,” by Marie D. Jackson, Juhyuk Moon, Emanuele Gotti, 
> Rae Taylor, Abdul-Hamid Emwas, Cagla Meral, Peter Guttmann, Pierre 
> Levitz, Hans-Rudolf Wenk, and Paulo J. M. Monteiro, appears in the 
> Journal of the American Ceramic Society.
>
> “Unlocking the secrets of Al-tobermorite in Roman seawater concrete,” 
> by Marie D. Jackson, Sejung Rosie Chae, Sean R. Mulcahy, Cagla Meral, 
> Rae Taylor, Penghui Li, Abdul-Hamid Emwas, Juhyuk Moon, Seyoon Yoon, 
> Gabriele Vola, Hans-Rudolf Wenk, and Paulo J. M. Monteiro, will appear 
> in American Mineralogist.
>
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> information visit www-als.lbl.gov/.
>
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>
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>
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