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The Cabrillo Bridge, entered on the National Register of Historic
Places in 1976, is one of the most historic bridges in
all of California. The bridge, which passes over California
Highway 163 in San Diego’s Balboa Park, has the
architectural appearance of seven closed-spandrel cast-in-place
reinforced concrete arches, and mimics the Spanish-Colonial
style. Structurally, however, it is composed of hollow
vertical sections with cantilevered box girders that form
the arched openings. The concrete walls are 6 to 24 in.
(15 to 61 cm) thick and made with board formed concrete. The original formwork from 1915
is still in place inside the columns.
Chunks of original concrete from beneath the arches had
become dislodged and fallen to the ground below. Concerns
about safety and potential structural performance problems
prompted an investigation to be done in connection with
bridge repairs being performed by the contractor and Department
of Transportation.
Inspection and test results showed the primary cause of
concrete spalling and delamination to be corrosion of
embedded steel reinforcement. Factors contributing to
steel corrosion over the bridge’s service life included
concrete carbonation, available moisture sources, and
depth of concrete cover over reinforcing steel; general
concrete quality; and chloride levels.
The consulting structural engineer’s report described
how the concrete’s durability potential could be
enhanced through further repairs, such as shotcrete or
form-and-pour patches, or alternative repairs involving
sacrificial anodes, penetrating corrosion inhibitors,
impressed current cathodic protection, or concrete realkalization,
included in an ongoing repair and maintenance program.
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Owner
State of California Department of Transportation
Sacramento, California
Project Engineer/
Designer
CK Arts
Bel Air, California
Repair Contractor
Erreca's Inc.
Deer Park, Texas
Material Supplier
BASF Building Systems
Shakopee, Minnesota |
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