Concrete Resistivity Test
(Electrical Resistivity)
Non-destructive measurement of electrical resistivity of concrete to assess its resistance to chloride ion penetration and predict corrosion risk — a key durability and quality control parameter.
What is the Concrete Resistivity Test?
The Concrete Resistivity Test measures the electrical resistance of concrete to predict its durability against chloride-induced corrosion of reinforcement. Higher resistivity indicates denser, less permeable concrete with lower corrosion risk. The test uses a Wenner four-probe array placed on the concrete surface to pass a small AC current and measure the voltage drop.
Conducted as per AASHTO T358 and RILEM TC 154-EMC, this test is widely used for quality control during construction, condition assessment of existing structures and acceptance testing for concrete mix designs. Global Lab uses NABL-calibrated Resipod resistivity meters for accurate, repeatable measurements.
Concrete Resistivity Test — Site Images
How the Concrete Resistivity Test is Conducted
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1Surface PreparationConcrete surface is moistened to ensure good electrical contact. Laitance or paint is removed if present.
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2Probe Array PlacementWenner four-probe electrode array (typically 50mm spacing) is placed on the concrete surface.
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3AC Current ApplicationA small alternating current is passed between outer electrodes. Voltage between inner electrodes is measured.
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4Resistivity CalculationBulk resistivity is calculated as ρ = 2πaV/I, where a is electrode spacing. Multiple readings are taken across the area.
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5Risk Classification & ReportingResistivity values are classified per RILEM table (>100 kΩ.cm = negligible risk). NABL report issued with mapped results.
Applicable Test Standards
| Standard | Title | Scope | Type |
|---|---|---|---|
| AASHTO T358 | Surface Resistivity Indication of Concrete's Ability to Resist Chloride Ion Penetration | Surface Resistivity | AASHTO |
| RILEM TC 154-EMC | Recommendations for the Measurement of Resistivity | Bulk Resistivity | RILEM |
| NT Build 492 | Chloride Migration Coefficient from Non-Steady State Migration | Migration Test | Nordic |
| IS 13311 | Non-Destructive Testing of Concrete — Recommendations | General NDT | Indian Standard |