Newsgroup: it.hobby.fai-da-te
Titolo: Sarete contenti di sapere che... [in inglese, sorry]

... hanno finalmente scoperto la struttura molecolare fondamentale del 
cemento idrato.
Non siete tutti piï¿œ felici, ora? :-)
Cement's Basic Molecular Structure Finally Decoded
==================================================
In the 2,000 or so years since the Roman Empire employed a naturally 
occurring form of cement to build a vast system of concrete aqueducts 
and other large edifices, researchers have analyzed the molecular 
structure of natural materials and created entirely new building 
materials such as steel, which has a well-documented crystalline 
structure at the atomic scale.
Oddly enough, the three-dimensional crystalline structure of cement 
hydrate -- the paste that forms and quickly hardens when cement powder 
is mixed with water -- has eluded scientific attempts at decoding, 
despite the fact that concrete is the most prevalent man-made material 
on earth and the focus of a multibillion-dollar industry that is under 
pressure to clean up its act. The manufacture of cement is responsible 
for about 5 percent of all carbon dioxide emissions worldwide, and new 
emission standards proposed by the U.S. Environmental Protection Agency 
could push the cement industry to the developing world.
[...] MIT Professor Sidney Yip, co-author of a paper published online 
in the Proceedings of the National Academy of Sciences (PNAS) during 
the week of Sept. 7 that announces the decoding of the 
three-dimensional structure of the basic unit of cement hydrate by a 
group of MIT researchers who have adopted the team name of Liquid 
Stone.
"We believe this work is a first step toward a consistent model of the 
molecular structure of cement hydrate, and we hope the scientific 
community will work with it," said Yip, who is in MIT's Department of 
Nuclear Science and Engineering (NSE). "In every field there are 
breakthroughs that help the research frontier moving forward. One 
example is Watson and Crick's discovery of the basic structure of DNA. 
That structural model put biology on very sound footing."
Scientists have long believed that at the atomic level, cement hydrate 
(or calcium-silica-hydrate) closely resembles the rare mineral 
tobermorite, which has an ordered geometry consisting of layers of 
infinitely long chains of three-armed silica molecules (called silica 
tetrahedra) interspersed with neat layers of calcium oxide.
But the MIT team found that the calcium-silica-hydrate in cement isn't 
really a crystal. It's a hybrid that shares some characteristics with 
crystalline structures and some with the amorphous structure of frozen 
liquids, such as glass or ice.
tutto l'articolo su
www.sciencedaily.com/releases/2009/09/090909141639.htm


 i veneziani saranno contenti di sapere che i loro palazzi poggiano su 
"solide fondamenta scientifiche" ! 

 .... hanno finalmente scoperto la struttura molecolare fondamentale del 

Una piccola nota linguistica.
Cement, cement hydrate e concrete sono 3 cose molto diverse. 
Nell'abstract sembrano usate come sinonimi... un muratore de' noantri 
non si sognerebbe mai di confondere cemento e calcestruzzo. Diciamo che 
l'estensore di sciencedaily si occupa d'altro, normalmente...
Peraltro, mi chiedevo quale potrebbe essere una traduzione plausibile di 
cement hydrate, cosï¿œ come definito nell'articolo. Cemento bagnato? :-D
Ciao...

 Ciao...
che ne dici di "malta idraulica di pozzolana"?
Claudio 

 Ciao...
  Esatto quando cio� � iniziato il processo di idratazione!
  felix.
-- 
Video meliora proboque, deteriora sequor.
questo articolo e` stato inviato via web dal servizio gratuito 
http://www.newsland.it/news
 segnala gli abusi ad 
ab...@newsland.it

 Ciao...
concrete e' il calcestruzzo...cement hydrate e' il cemento a cui e' 
stata gia' aggiunta l'acqua e si e' indurito; non e' il cemento 
idraulico (tipo Portland)
Caldarella