Half-Cell Potential Mapping
Electrochemical Corrosion Probability Assessment
Overview
Half-cell potential mapping is the standard electrochemical technique for assessing the probability of active reinforcement corrosion in concrete structures. SiteOps uses this technique to determine where corrosion is actively occurring, where it is not, and where conditions are transitioning toward corrosion onset.
The technique measures electrical potential difference between embedded steel reinforcement and a reference electrode placed on the concrete surface. More negative readings indicate higher corrosion probability. ASTM C876 provides standard interpretation criteria.
Half-cell mapping is performed on a systematic grid across the structure, producing contour maps that visualise the spatial distribution of corrosion probability. These maps are critical for proportionate remediation design — showing exactly where intervention is needed.
Half-cell mapping consistently demonstrates that the spatial extent of active corrosion is less than visual assessment alone would suggest, enabling targeted and cost-effective remediation.
Applications
Corrosion Probability Assessment
Systematic mapping of reinforcement corrosion probability to distinguish active from passive zones.
Remediation Scope Definition
Delineating actual extent of corrosion activity for proportionate remediation boundaries.
Condition Monitoring
Periodic surveys to track changes in corrosion state over time.
Post-Repair Verification
Verifying remediation has re-established passive conditions in treated zones.
Marine Infrastructure
Systematic corrosion assessment in marine and coastal environments.
Technical specifications
| Reference Electrode | Cu/CuSO₄ (CSE) |
|---|---|
| Grid | 300mm × 300mm (adjustable) |
| Active Corrosion | More negative than -350mV CSE (>90% probability) |
| Passive | Less negative than -200mV CSE (>90% probability) |
| Output | Contour maps of corrosion probability |
| Standards | ASTM C876, RILEM TC 154-EMC |
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FAQ
Common questions
What does half-cell potential measure?+
It measures the electrochemical potential between embedded steel and a reference electrode — reflecting the thermodynamic tendency of the steel to corrode.
Can it be used on all concrete?+
It requires electrical continuity with the reinforcement and sufficiently moist concrete. Very dry concrete may require modified techniques.
Deploy HCP on your asset
Share drawings, exposure conditions, and programme constraints — we will propose an investigation scope aligned to Australian standards and your risk profile.
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