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In the summer of 2002, the Owner undertook the
3rd phase of a large rehabilitation project on a 1.5 mile
elevated section of Interstate Route 480 in downtown Omaha.
Constructed in the early 1970s, the viaduct had experienced
significant chloride induced corrosion and deterioration to
the concrete deck and substructure. The overall project
included the rehabilitation of sixty-six hammer-head piers,
application of a chloride resistive sealer, and complete deck
replacement.
With the replacement of the deck, the long-term performance of
the repaired substructure was a concern. In order to extend
the service life of the concrete repairs and extend the life
of the substructure, Owner elected to perform electrochemical
chloride extraction, install embedded galvanic anodes in the
patch repairs and apply a chloride resistive sealer to the
substructure.
Twenty-three of the hammer-head piers were treated with
electrochemical chloride extraction, a technique that removes
chloride ions from concrete and restores the rebar to a
passive condition. Fifty-five of the piers had embedded
galvanic anodes installed within the patch repairs, to extend
the life of the patch repairs. Finnaly a chloride resistive
sealer was applied to all sixty-six piers to prevent future
chloride contamination.
The application of advanced rehabilitation technologies
including chloride extraction and embedded galvanic anodes
played a vital role in restoring this structure, and assuring
that the substructure will serve as well as the new deck.
These technologies allowed the Owner to tailor the level of
protection to suit the varying needs of the structure,
addressing future corrosion concerns as well as current
problems.
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