Which test method is used to determine the air-void content of fresh concrete in the field?

Which test method is used to determine the air-void content of fresh concrete in the field?

• A. Air content test using the pressure method (ASTM C231).
• B. Slump test
• C. Concrete cylinder compressive strength test
• D. Slump flow test

Answer: (A)

Determining air-void content in fresh concrete in the field is done with the air content test using the pressure method. This method traps a sample of fresh concrete in a sealed air meter and applies a known pressure. The pressure change is related to the amount of air present in the pores of the concrete, so you can calculate the air content as a percentage of the concrete’s volume. This is specifically a field method because it gives a quick, direct read on how much air is entrained in the mix, which influences workability, durability, and finishing. The other tests don’t measure air voids: the slump test checks how workable the concrete is; the cylinder compressive strength test assesses strength after curing; and the slump flow test evaluates the spread of flowing or self-consolidating concrete.

Determining air-void content in fresh concrete in the field is done with the air content test using the pressure method. This method traps a sample of fresh concrete in a sealed air meter and applies a known pressure. The pressure change is related to the amount of air present in the pores of the concrete, so you can calculate the air content as a percentage of the concrete’s volume. This is specifically a field method because it gives a quick, direct read on how much air is entrained in the mix, which influences workability, durability, and finishing.

The other tests don’t measure air voids: the slump test checks how workable the concrete is; the cylinder compressive strength test assesses strength after curing; and the slump flow test evaluates the spread of flowing or self-consolidating concrete.