Manual on Service Life of Corrosion-Damaged Reinforced Concrete Bridge Superstructure Elements (2006) / Chapter Skim
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Pages 3-12
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From page 3... ...
In addition to modeling the expected future damage, this protocol proposes a method of quantifying the future propensity for corrosion by using an index that C H A P T E R 2 Condition Evaluation of Superstructure Elements
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For bridge superstructures exposed to adverse environments, the question is not if corrosion will occur, but when it will occur and when a major repair will be required. Two types of corrosion condition surveys are proposed: the "Preliminary Corrosion Condition Evaluation" (PCCE)
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From page 5... ...
In planning the repair of a bridge superstructure element, it is important to examine the areas that have not yet deteriorated and will not be repaired. If the undamaged areas have a propensity for corrosion, some form of corrosion mitigation system will be required to ensure that corrosion in these areas does not reduce the service life of the concrete element.
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From page 6... ...
Impact Echo Impact echo is a process in which a mechanical impact produces a stress wave in a material. This stress wave travels through the material until a discontinuity is encountered.
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From page 7... ...
As with impact echo, there may be some difficulties in using ultrasonic pulse velocity on an HMA surface because of the rough surface texture typical of HMA layers and the difficulty of establishing a proper contact with the surface. Infrared Thermography Infrared thermography is based on the principle that defects within a material will alter the way heat flow is dissipated at the surface of that material [8, 9]
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From page 8... ...
Shallow cover on a structure will lead to more rapid accumulation of chloride ions at the steel depth in excess of the threshold required to initiate corrosion and subsequently results in faster development of concrete damage. The location of a reinforcement bar and its depth of cover can be obtained nondestructively by using a pachometer or a covermeter.
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From page 9... ...
The electrical interaction of embedded reinforcing bars and external metallic components of bridge superstructures influence the results of all electrical tests run during a condition survey. The corrosion potential survey is particularly sensitive to continuity because all the reinforcing steel within a given area must be continuous.
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From page 10... ...
• An increasing probability of corrosion activity exists if the half-cell potential falls between −0.200 V and −0.350 V This probability depends on factors such as chloride content at the reinforcing bar level, moisture content of the concrete, temperature, etc.
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From page 11... ...
It is a lot easier and faster to collect a core than to collect powdered concrete sample from six depths from a given location. In addition to chloride ion content analysis, the core can be used for carbonation testing.
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From page 12... ...
It should also be performed if application of a cathodic protection system or electrochemical chloride extraction is a viable option for corrosion control on the subject superstructure element. Half-cell potential and corrosion rate measurement are conducted to ascertain the state of corrosion in presently undamaged areas.
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