Concrete Air Content: What the Test Means and What Changes It
Understand entrained/entrapped air, field test methods, durability context, and why air can change during handling.
Editorial review: 2026-09-29 · How we review technical content
Key takeaways
- Air content is a mixture property that can affect freeze-thaw durability, workability, density, pump behavior, finishing, and strength. The required value and test method depend on the concrete type, exposure, aggregate, and project specification.
- Identify whether air is specified, the target/tolerance, concrete type and aggregate restrictions, sampling point, and which ASTM method applies.
- The pressure and volumetric air methods are not interchangeable for every concrete. Use the method required for the aggregate/concrete and current ASTM procedure.
Why this topic matters
Air content is a mixture property that can affect freeze-thaw durability, workability, density, pump behavior, finishing, and strength. The required value and test method depend on the concrete type, exposure, aggregate, and project specification.
What to establish before concrete arrives
Identify whether air is specified, the target/tolerance, concrete type and aggregate restrictions, sampling point, and which ASTM method applies. Confirm whether pumping or other handling means air should be checked before and/or after a process under the testing plan.
Field execution
Perform the specified test on a representative sample, using properly maintained/calibrated equipment and the required consolidation. Do not treat a meter number as meaningful if the sample or apparatus was handled casually.
Verification and documentation
Record air with temperature, slump, unit weight when tested, batch identification, placement location, admixture adjustments, and sampling point. Trends across loads can be more informative than one isolated result.
Failure modes and troubleshooting
Air can change because of mixture variability, temperature, mixing, haul time, pump configuration, vibration, admixture interactions, or testing error. Excessive finishing of air-entrained exterior flatwork can also contribute to surface problems even when measured air was acceptable.
How to make the decision
Compare the test with the specified acceptance range and follow the project procedure for adjustment/retest/rejection. Avoid jobsite “fixes” that have not been approved by the producer/specification.
Limits of generic guidance
The pressure and volumetric air methods are not interchangeable for every concrete. Use the method required for the aggregate/concrete and current ASTM procedure.
References & further reading
- ASTM Cement and Concrete Standards — Primary catalog for current concrete materials and test methods.
- American Concrete Institute (ACI) — Primary source for concrete codes, specifications, guides, and technical resources.
- ACI SPEC-301-20 — Specifications for Concrete Construction — Reference specification used when incorporated into project specifications.