Oxygen Permeability Test of Concrete
(OPI — Durability Index)
Measurement of the permeability of concrete to oxygen gas flow under pressure — providing a rapid, sensitive durability index for assessing the interconnected porosity and transport properties of hardened concrete.
What is the Oxygen Permeability Test of Concrete?
The Oxygen Permeability Test measures the rate of oxygen gas flow through a 68mm thick concrete disc under an applied pressure differential of 100 kPa. The Oxygen Permeability Index (OPI) — expressed as −log₁₀(k) — provides a sensitive, rapid indicator of concrete permeability that is more discriminating than water absorption for durability assessment.
Developed at the University of Cape Town and adopted by SANS, this test is used internationally for concrete durability specification and quality control, particularly for marine, industrial and infrastructure concrete. Global Lab uses the standard South African Durability Index test apparatus with automated data logging for accurate OPI determination.
Oxygen Permeability Test of Concrete — Site Images
How the Oxygen Permeability Test of Concrete is Conducted
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1Specimen Preparation68mm thick disc cut from 100mm diameter core or cast cylinder. Oven-dried at 50°C for 7 days.
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2Disc MountingDried disc mounted in stainless steel permeability cell. Silicone sealant applied to edges to prevent bypass flow.
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3Pressure Application100 kPa oxygen pressure applied to one face. Pressure decay measured on downstream side over time.
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4Permeability Coefficient CalculationOxygen permeability coefficient k calculated from pressure decay curve using Darcy's law.
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5OPI Determination & ReportOPI = −log₁₀(k). Classified per durability index criteria. NABL report within 7 days.
Applicable Test Standards
| Standard | Title | Scope | Type |
|---|---|---|---|
| SANS 3001-CO3-2 | Concrete Durability Index Testing — Oxygen Permeability Test | OPI Test | South African Standard |
| NT Build 492 | Chloride Migration Coefficient from Non-Steady State Migration | Migration Test | Nordic |
| ASTM C1202 | Standard Test Method for Electrical Indication of Concrete Ability to Resist Chloride Ion Penetration | RCPT Reference | ASTM |
| IS 14959 Part 2 | Determination of Water Absorption of Concrete | Absorption | Indian Standard |