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WIRED!- Saving Oregon’s Historic Bridges
from a Rusty Demise
By
Tami Fung and Jesse Saveriano
Mentors:
Amy Zelich, Nadja Orlova, and Dr. Milo Koretsky
problem: Many of Oregon’s historic bridges are
undergoing serious corrosion due to the reaction between the Iron
Rebar inside the concrete of the bridge, and the salt, water,
and Oxygen which surrounds them.
Possible solutions: One solution to this problem which
Scientists and Engineers have been researching, is the use of Cathodic
Protection, where by a Coating of Zinc is sprayed to
the bottom of the Bridges and wired to the Iron Rebar in the
bridge itself. All the wires are connected to a power source so
that current runs through the bridge. This causes and exchange of
electrons which keeps the Iron in its pure metal form.
experiment 1: 3 Iron plates were placed in 3 boxes
filled with sand and a Water and Salt solution. In Box #1 the
Iron was be itself. In Boxes #2 and #3, the Iron plate was wired
to a Zinc plate which was also immersed in the sand/water mix.
The wires were connected to a power source and received .5 mA of
current. A stream of compressed air was added to each box. The
next day all 3 Iron plates had corroded nearly the same.
experiment 2: The 3 plates were cleaned and then
placed back in their boxes, this time with no air and a higher
current in Box #2 and #3. The solution in Box #2 was also
modified so that it had a more Basic pH. Box #1(which was by
itself) corroded the most. Box #2 corroded the least, and Box #3
was similar to Box #2, but corroded slightly less.
conclusions: These experiments prove that Cathodic
Protection, and altering the pH of concrete can be successful
tools in prolonging the life of Oregon’s historic bridges.
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