Corrosion Rate Test
(Linear Polarization Resistance)
Quantitative in-situ measurement of the instantaneous corrosion rate of reinforcing steel in concrete using Linear Polarization Resistance — providing actual corrosion current density for structural life assessment.
What is the Corrosion Rate Test?
The Corrosion Rate Test uses Linear Polarization Resistance (LPR) to measure the instantaneous corrosion current density (Icorr in μA/cm²) of embedded reinforcing steel. Unlike the half-cell potential test which gives only probability, the corrosion rate test provides the actual rate of steel section loss — a critical parameter for remaining service life calculation.
Conducted as per ASTM C876 and RILEM TC 154-EMC using the Galvapulse instrument, corrosion is classified as passive (<0.1 μA/cm²), low (0.1–0.5), moderate (0.5–1.0) or high (>1.0 μA/cm²). Combined with cover depth, actual remaining time to structural damage can be estimated.
Corrosion Rate Test — Site Images
How the Corrosion Rate Test is Conducted
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1Surface WettingConcrete surface wetted to ensure electrical continuity with rebar.
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2Rebar ConnectionElectrical connection made to reinforcing steel through drilled hole.
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3Sensor PlacementGalvapulse LPR sensor placed on wetted concrete surface over rebar.
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4Polarization MeasurementSmall DC signal applied. Polarization resistance Rp measured.
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5Icorr Calculation & ReportIcorr = B/Rp×A. RILEM classification applied. NABL report within 24 hours.
Applicable Test Standards
| Standard | Title | Scope | Type |
|---|---|---|---|
| ASTM C876 | Standard Test Method for Corrosion Potentials of Uncoated Reinforcing Steel in Concrete | Corrosion Test | ASTM |
| RILEM TC 154-EMC | Recommendations for the Measurement of Corrosion Rates | Corrosion Rate | RILEM |
| BS EN 12696 | Cathodic Protection of Steel in Concrete | Electrochemical | British Standard |
| IS 13311 | Non-Destructive Testing of Concrete — Recommendations | General NDT | Indian Standard |