Posted Jul 2, 2012, 1:14 AM
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Mortaaaaaaaaar!
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Join Date: Aug 2007
Location: Naugatuck, CT/Worcester,MA
Posts: 3,506
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As a future civil engineer, building with carbon nanotubes or graphene is certainly one of my wet dreams. The light weight and high strength are certainly a plus in my book, but what I really like about these carbon based materials is their stiffness. I get the desire for stiffer and not just stronger materials from my brief experience in my design of steel structures class. There I found the the size of steel members was often limited by the stiffness of mebers rather than the strenght. A given beam would often be quite strong enough to withstand the design load, but it would deflect beyond acceptable limits. This problem gets worse when you go from the older 36 ksi steels to the current 50 ksi steels, and 70-100 ksi steels in the future. Alas, whatever the strength of steel is, it has the same stiffness. This is where graphene could help. Graphene has a stiffness of ~1 terapascal, compared to 200 gigapascal for steel.
However, the full stiffness isn't realized in current composite materials, since some of the volume is taken up by the binder, which weakens the material. It is also of course still enormously expensive, and not available in anywhere near the amounts required for civil construction. Indeed, the more basic carbon fiber is just becoming cheap and available enough to be used out side of niche applications like racecars and military aircraft, and can now be used in significant quantities in commercial aircraft now, and 'regular' passenger vehicles within the next decade.
Bottom line is that the price has to come down more first before they'll see anysort of mass adoption in infrastructure.
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