Science Briefs

June 9, 2013 

See Tar Heel ingenuity at Maker Faire

Maker Faire North Carolina, – a family-friendly show-and-tell-style celebration of citizens’ inventions, innovations and ingenuity – returns June 15 to the Kerr Scott Building on the N.C. State Fairgrounds in Raleigh. Admission to the fair (10 a.m.-6 p.m.) is $10 for adults and $5 for ages 7-17. Details: Staff reports

Engineers: Let’s try Roman concrete

In a quest to make concrete more durable and sustainable, an international team of geologists and engineers has found inspiration in the ancient Romans, whose massive concrete structures have withstood the elements for more than 2,000 years.

Using the Advanced Light Source at Lawrence Berkeley National Laboratory, a research team from the University of California at Berkeley examined the fine-scale structure of Roman concrete. It described for the first time how the extraordinarily stable compound – calcium-aluminum-silicate-hydrate – binds the material used to build some of the most enduring structures in Western civilization.

The discovery could help improve the durability of modern concrete: Within 50 years, it often shows signs of degradation, particularly in ocean environments.

The manufacturing of Roman concrete also leaves a smaller carbon footprint than its modern counterpart. The process for creating Portland cement, a key ingredient in modern concrete, requires fossil fuels to burn calcium carbonate (limestone) and clays at about 2,642 degrees Fahrenheit. Seven percent of global carbon dioxide emissions every year comes from this activity. The production of lime for Roman concrete, however, is much cleaner, requiring temperatures that are two-thirds of that required for making Portland cement.

Part of the researchers’ findings were published last week in the online Journal of the American Ceramic Society; another paper is scheduled to appear in October in the journal American Mineralogist. UC Berkeley News Service

Pebbles hint at rivers on Mars

Pebbles and sand scattered near an ancient Martian river network may present the most convincing evidence yet that the frigid deserts of the red planet were once a habitable environment traversed by flowing water.

Scientists with NASA’s Mars Science Laboratory mission report in the journal Science the discovery of sand grains and small stones that bear the telltale roundness of river stones and are too heavy to have been moved by wind. The researchers estimated that the sediment was produced by water that moved at a speed between that of a small stream and a large river, and had a depth of roughly an inch to nearly 3 feet.

Co-author Kevin Lewis, a Princeton University associate research scholar in geosciences and a participating scientist on the Mars mission, said that the rocks and sand are among the best evidence so far that water once flowed on Mars, and suggest that the planet’s past climate was wildly different from what it is today.

The researchers analyzed sediment taken from a Martian plain that abuts a sedimentary deposit known as an alluvial fan. Alluvial fans are composed of sediment left over when a river spreads out over a plain then dries up; they are common on Earth in arid regions such as California’s Death Valley. Princeton Journal Watch

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