introduction the service life of concrete elements in highway bridges is often limited by the...
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-285 mV
W to E
-170 mV
-103 mV
-136 mV
-160 mV
-250 mV
-373 mV
-352 mV
Top
(a)
-425 mV
W to E
-420 mV
-337 mV
-332 mV
-335 mV
-330 mV
-350 mV
-333 mV
Bottom
(b)
-684 mV
W to E
-736 mV
-720 mV
-684 mV
-665 mV
-676 mV
-688 mV
-687 mV
Top
(a)
-558 mV
W to E
-520 mV
-431 mV
-397 mV
-386 mV
-458 mV
-526 mV
-570 mV
Bottom
(b)
-373 mV
-352 mV -250 mV
-285 mV -160 mV
-170 mV
-103 mV
-136 mV
-350mV
-333 mV -330 mV
-425 mV -335 mV
-420 mV
-337 mV
-332 mV
-526 mV
-570 mV -458 mV
-558 mV -386 mV
-520 mV
-431 mV
-397 mV
-688 mV
-687 mV -676 mV
-684 mV -665 mV
-736 mV
-720 mV
-684 mV
-285 mV
W to E
-170 mV
-103 mV
-136 mV
-160 mV
-250 mV
-373 mV
-352 mV
Top
(a)
-425 mV
W to E
-420 mV
-337 mV
-332 mV
-335 mV
-330 mV
-350 mV
-333 mV
Bottom
(b)
-684 mV
W to E
-736 mV
-720 mV
-684 mV
-665 mV
-676 mV
-688 mV
-687 mV
Top
(a)
-558 mV
W to E
-520 mV
-431 mV
-397 mV
-386 mV
-458 mV
-526 mV
-570 mV
Bottom
(b)
-285 mV
W to E
-170 mV
-103 mV
-136 mV
-160 mV
-250 mV
-373 mV
-352 mV
Top
(a)
-425 mV
W to E
-420 mV
-337 mV
-332 mV
-335 mV
-330 mV
-350 mV
-333 mV
Bottom
(b)
-684 mV
W to E
-736 mV
-720 mV
-684 mV
-665 mV
-676 mV
-688 mV
-687 mV
Top
(a)
-558 mV
W to E
-520 mV
-431 mV
-397 mV
-386 mV
-458 mV
-526 mV
-570 mV
Bottom
(b)
-373 mV
-352 mV -250 mV
-285 mV -160 mV
-170 mV
-103 mV
-136 mV
-350mV
-333 mV -330 mV
-425 mV -335 mV
-420 mV
-337 mV
-332 mV
-526 mV
-570 mV -458 mV
-558 mV -386 mV
-520 mV
-431 mV
-397 mV
-688 mV
-687 mV -676 mV
-684 mV -665 mV
-736 mV
-720 mV
-684 mV
IntroductionThe service life of concrete elements in highway bridges is often limited by the corrosion deterioration of reinforcing bars. In cold regions, the corrosion rate of concrete bridge columns is accelerated by the use of deicing solutions during the winter season. The corrosion process causes cracking, spalling, and delamination of the reinforced concrete structures and increases the cost of rehabilitation and maintenance. In Wisconsin, fiberglass wrapping has been used to protect reinforced concrete columns from deicing salts. In this method, the lower part of the column is wrapped with 1/8 to 1/4 in.-thick fiberglass tube to create a barrier between the concrete surface and the deicing salts sprayed by the passing vehicles.
ObjectivesIn this study, field tests including wave propagation methods, half-cell potential, and measurement of chloride ion intrusion were conducted on fiberglass wrapped columns in I-90 and I-94 bridges to assess the effectiveness of the fiberglass wrapping in reducing the corrosion-induced degradation rate of the columns.
P-wave Velocity TestsTo evaluate the integrity of wrapped concrete columns, the P-wave velocity profiles were obtained along different directions. The crosshole and circular-type tomographic images show locations of degraded concrete zones caused by steel corrosion.
AcknowledgementsThe funding was provided by the Wisconsin Highway Research Program (WHRP Project 0092-07-07) and by the Midwest Regional University Transportation Center (MRUTC). The content of this poster does not necessarily reflect the views of the funding agencies. Mr. Alex Summitt collaborated with the field data collection.
Half-cell Potential TestsHalf-cell potential measurements are used to evaluate the electro-chemical activity generated during corrosion processes (ASTM C876).
Chloride Ion Intrusion MeasurementsChloride ion (Cl-) contamination is caused when splashed saline solution progresses by diffusion into the concrete. Cl- content vs. depth profiles are good indicators of the corrosion potential of reinforcing bars in concrete. In some cases, the Cl- content is lower in wrapped columns than in wrapped locations. However in some wrapped columns, the Cl- content may still be greater than the ACI recommended corrosion threshold level. Therefore corrosion conditions remain even after the application of the wrap.
Sectional views of half-cell potential readings in wrapped columns.Corrosion, delamination and rehabilitation using fiberglass wraps
ConclusionsP-wave travel-time tomography, half-cell potential measurements, and Cl- content vs. depth profiles were used to test the effectiveness of fiberglass wraps as a protective barrier against rebar corrosion in concrete columns. The effectiveness of fiberglass wraps can be evaluated by measuring Cl- content in depth. It is observed that Cl- concentrations in wrapped columns are lower than those of unwrapped columns. However, in many of the wrapped columns the conditions for corrosion remain and future maintenance operation will be required.
Sampling locations and Cl- content profiles with chloride diffusion solutionCorrosion process in reinforced concrete
P-wave travel time tomographic images of concrete columns
Half cell potential reference values for evaluating corrosion risk
< -500 mVSevere corrosion
< -350 mVHigh (90% risk of
corrosion)
-350 to -200 mVUncertain
(intermediate)
>-200 mVLow (10% risk of
corrosion)
Half-cell potentialRisk of corrosion
< -500 mVSevere corrosion
< -350 mVHigh (90% risk of
corrosion)
-350 to -200 mVUncertain
(intermediate)
>-200 mVLow (10% risk of
corrosion)
Half-cell potentialRisk of corrosion
Performance Evaluation of Fiberglass Wrapped Concrete Bridge ColumnsKyu-Sun Kim, Dante Fratta and José A. Pincheira
University of Wisconsin – Madison