Use a Half-Cell Potential Map for the Corrosion Question It Can Support
An electrical-potential map can add information to a reinforced-concrete review, but its legend should not be read as a direct measure of how much steel remains. Before presenting the map in a capital-planning packet, ask the specialist to explain the question it answers and the information needed alongside it.
Identify what is being measured
FHWA describes half-cell potential testing as an indicator of the potential for active corrosion. Its guidance also states that the test does not measure the degree of existing corrosion. This is background for interpreting a supplied report, not a procedure or an offer of testing services. Keep the actual method, reference information and qualified interpretation with the map rather than copying only a color category into an asset register.
Ask how the actual assembly affects the evidence
Coatings, overlays, electrical connectivity and site conditions can matter to whether a method is applicable and how results are interpreted. Have the responsible specialist explain relevant constraints and any areas that could not be assessed appropriately. Do not remove finishes, expose reinforcement or make electrical connections to help complete an inquiry. A color change between two documents should not be called a corrosion-rate change until the relevant reviewer has established that the records and interpretation support that conclusion.
Combine complementary evidence without merging its meaning
A chemical result can describe a different question from an electrical-potential survey; neither should be silently relabeled as measured section loss or remaining capacity. Ask what other observations or specialist work are needed for the actual repair or operating decision. Keep engineering conclusions with the appropriate licensed professional and preserve the report’s uncertainty. The assessment handoff should explain which evidence indicates possible activity, which evidence concerns physical condition and which question remains unresolved. This makes a management discussion clearer without converting a probability-oriented map into a repair timetable or a whole-structure safety assurance.
Copyable worksheet
Use one row for each field. Mark unknown information clearly and retain the original records.
| Field | Your note |
|---|---|
| Purpose and quantity actually measured | ____________________ |
| Report legend and qualified interpretation | ____________________ |
| Assembly constraints and excluded areas | ____________________ |
| Complementary physical-condition evidence | ____________________ |
| Decision still requiring specialist review | ____________________ |
Worked example
Illustrative example: a fictional facilities team receives a half-cell potential map and a separate material report. It asks the specialist to explain how the records complement one another. The board summary does not turn a map category into a claimed percentage of steel loss or a predicted failure date.