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Using the most modern tools of materials research, a team from the National Institute of Standards and Technology (NIST) (Gaithershurg, Man-land) and Northwestern University (Evanston, Illinois) say they have shed new light on a very old construction material cement. Their research may lead to improvements in the formulation and use of concrete that could save hundreds of millions of dollars in annual maintenance and repair costs for concrete structures and infrastructure around the world,
Concrete may be the world's most widely used manufactured material-more than 11 billion metric tons are consumed each year-but it also is one of the more complex. Concrete is a mixture of cement and water, which together form a cement paste, along with sand and gravel. The cement paste, a gel of calcium silicate hydrate (CSH), binds even-thing together to form concrete. While cement and concrete were known to the Romans, who used them In such structures as the Colosseum and Pantheon, questions still remain about the chemical reactions between cement and water that result in this strong and durable material-and, in particular, how it is structured at the nano- and microscale, and how...