Thanks for sharing this Bruce! On Mon, Jun 10, 2013 at 7:38 PM, Bruce Majors <[email protected]>wrote:
> > > --------- > > > http://www.theatlanticcities.com/technology/2013/06/could-2000-year-old-recipe-cement-be-superior-our-own/5800/ > Could a 2,000-Year-Old Recipe for Cement Be Superior to Our Own? > > - HENRY GRABAR <http://www.theatlanticcities.com/authors/henry-grabar/> > - JUN 07, 2013 > - 7 > COMMENTS<http://www.theatlanticcities.com/technology/2013/06/could-2000-year-old-recipe-cement-be-superior-our-own/5800/#disqus_thread> > > **[image: Could a 2,000-Year-Old Recipe for Cement Be Superior to Our > Own?]**John Peter Oleson**** > > - > - > - > - inShare5 > - > Share<http://www.theatlanticcities.com/technology/2013/06/could-2000-year-old-recipe-cement-be-superior-our-own/5800/#> > - > Print<http://www.theatlanticcities.com/technology/2013/06/could-2000-year-old-recipe-cement-be-superior-our-own/5800/#> > - Share on > emailEmail<http://www.theatlanticcities.com/technology/2013/06/could-2000-year-old-recipe-cement-be-superior-our-own/5800/#> > > The Romans didn't invent concrete, but they did establish its versatility. > The structural ingenuity of the Baths of Caracalla, the Pont du Gard and > the Pantheon would not be surpassed for a thousand years. > > But if the dazzling concrete curves and cantilevers of modern architecture > have matched the Romans' for style and structure, today's standard recipe, > 2,000 years later, remains in some ways inferior. > > New > research<http://newscenter.lbl.gov/news-releases/2013/06/04/roman-concrete/> > into > Pozzolanic cement, so named for the corner of the Bay of Naples where the > ash of Mount Vesuvius facilitated its creation, shows the advantages of the > Roman method. Their mixture for hydraulic concrete, a blend of volcanic ash > and lime, has a tougher molecular structure than its modern equivalent. > It's unusually resistant to fragmenting and nearly immune to the corrosion > caused by salt water. That's why Roman jetties and port structures have > weathered two salty millennia, while our maritime concrete creations > degrade within a matter of decades. > > So why aren't we doing as the Romans did? > > For one thing, the methods largely vanished with the fall of Rome. "They > really haven't been examined at a very fine scale until now," says Marie > Jackson, one of the researchers who has been studying the molecular > composition of Roman seawater concrete. "There's been a general lack of > knowledge about what the Roman model could produce." > > One problem with ordinary Portland > cement<http://en.wikipedia.org/wiki/Portland_cement>, > which is used, along with pebbles and sand, to make most of the modern > world's concrete, is that it requires an enormous amount of energy. The > lime and clay mixture must be heated at over 2,500 degrees Fahrenheit, > making the manufacture of cement the third-largest > source<http://www.scientificamerican.com/article.cfm?id=cement-from-carbon-dioxide> > of > greenhouse gas emissions in the U.S., and responsible for 5 to 10 > percent<http://web.mit.edu/newsoffice/2007/concrete.html> of > carbon dioxide production worldwide. > > In contrast the Roman method, recorded by Vitruvius, requires 10 percent > less lime by weight and two-thirds the baking temperature, greatly reducing > its environmental impact. It also has a molecular structure that insures > strength and longevity, meaning that, like the piers of the great Roman > harbors, it seldom requires replacement. Aluminum-rich ash, reacting with > lime and seawater, forms a highly stable mineral called > tobormorite<http://en.wikipedia.org/wiki/Tobermorite>, > which modern cement can only imitate. > > "What I'd like to see happen is that we learn to understand the fine-scale > structure of this material, and begin at least experimental work to > reproduce it so it can become a mainstream building material," Jackson says. > > *Top image: Soli-Pompeiopolis, with the concrete on the left. Courtesy of John > Peter Oleson <http://web.uvic.ca/~jpoleson/>.* > > __._,_.___ > Reply via web > post<http://groups.yahoo.com/group/NewAmericanDemocrats/post;_ylc=X3oDMTJyYjQxOGZqBF9TAzk3MzU5NzE0BGdycElkAzEzOTUzODM4BGdycHNwSWQDMTcwNTA2MDEzNgRtc2dJZAMzNDM3MgRzZWMDZnRyBHNsawNycGx5BHN0aW1lAzEzNzA3MDExNzY-?act=reply&messageNum=34372> > Reply > to sender Reply to group Start a New > Topic<http://groups.yahoo.com/group/NewAmericanDemocrats/post;_ylc=X3oDMTJmdGVlMTR2BF9TAzk3MzU5NzE0BGdycElkAzEzOTUzODM4BGdycHNwSWQDMTcwNTA2MDEzNgRzZWMDZnRyBHNsawNudHBjBHN0aW1lAzEzNzA3MDExNzY-> > Messages > in this > topic<http://groups.yahoo.com/group/NewAmericanDemocrats/message/34372;_ylc=X3oDMTM3Z29vdDFuBF9TAzk3MzU5NzE0BGdycElkAzEzOTUzODM4BGdycHNwSWQDMTcwNTA2MDEzNgRtc2dJZAMzNDM3MgRzZWMDZnRyBHNsawN2dHBjBHN0aW1lAzEzNzA3MDExNzYEdHBjSWQDMzQzNzI->(1) > Recent Activity: > > > Visit Your > Group<http://groups.yahoo.com/group/NewAmericanDemocrats;_ylc=X3oDMTJmaWRyZDAzBF9TAzk3MzU5NzE0BGdycElkAzEzOTUzODM4BGdycHNwSWQDMTcwNTA2MDEzNgRzZWMDdnRsBHNsawN2Z2hwBHN0aW1lAzEzNzA3MDExNzY-> > [image: Yahoo! > Groups]<http://groups.yahoo.com/;_ylc=X3oDMTJlbGx2Y3R0BF9TAzk3NDc2NTkwBGdycElkAzEzOTUzODM4BGdycHNwSWQDMTcwNTA2MDEzNgRzZWMDZnRyBHNsawNnZnAEc3RpbWUDMTM3MDcwMTE3Ng--> > Switch to: Text-Only, Daily Digest • Unsubscribe • Terms of > Use<http://docs.yahoo.com/info/terms/>• Send > us Feedback > . > > __,_._,___ > > -- > -- > Thanks for being part of "PoliticalForum" at Google Groups. > For options & help see http://groups.google.com/group/PoliticalForum > > * Visit our other community at http://www.PoliticalForum.com/ > * It's active and moderated. 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