BUFFALO, N.Y. -- The failure of levees in the wake of Hurricane
Katrina points out the need for new technologies to strengthen
levees and monitor their reliability, according to Deborah D. L.
Chung, Ph.D., a University at Buffalo materials scientist and
inventor of "smart concrete."
"The technology used to build levees is really very primitive --
sometimes it involves just the piling of dirt. Surely there's a lot
of room to use higher technologies than that," says Chung, Niagara
Mohawk Professor of Materials Research and director of the
Composite Materials Research Laboratory in the UB School of
Engineering and Applied Sciences.
Chung's smart concrete, patented in 1998, may be one such
technology whose time has come for commercial use -- not only in
the construction of levees, but for a range of disaster and
homeland security applications.
With smart concrete, short carbon fibers are added to the
conventional concrete mixture. This modification gives the concrete
the ability to detect stress and tiny deformations in the concrete.
In the presence of structural flaws -- within a levee made of smart
concrete, for example -- the concrete's electrical resistance
increases. This change can be detected by electrical probes placed
on the outside of structures.
"You could use a meter to continuously monitor stress and
deformation within levees made of smart concrete," Chung explains.
"When deformations in the levee deviate from an acceptable
baseline, an alarm could be triggered."
Similarly, the electrical properties of smart concrete could be
used to detect underground stress that builds prior to an
earthquake, to monitor building occupancy for intruders or for
stragglers during an evacuation, and to monitor traffic flow in an
emergency or around U.S. borders, Chung says.
Chung, who also has studied the use of continuous carbon fibers
in the form of composites, suggests that some levees could be
encased in a shell composed of such composites, which are similar
to the material used to form the bodies of jet aircraft.
"If you use that as the outer shell of a levee, you could make
use of the carbon fiber's electrical conductivity to monitor fiber
breakage," she says. "So in addition to serving as levee
reinforcement, the shell also serves as a sensor of damage."
According to Chung, use of smart concrete would increase
construction costs by 30 percent, which is a main reason industry
has not adopted its use, she says. Of course, reconstruction costs
after a disaster can run much higher, she points out.
"People might say they like sensing, but in real life do they
really want their bridge or their highway to be smart," Chung asks.
"When it comes to real construction projects, all they really care
about is mechanical behavior, and every penny counts in the bidding
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