The common Type B pressure meter (ASTM C231) is filled with concrete, clamped shut, pumped to a set pressure and read directly for percent air from the pressure drop. Lightweight aggregate concrete needs the volumetric roll-a-meter (ASTM C173), because air in the porous aggregate fools the pressure method. Specs usually allow plus or minus 1.5 percentage points around the target.
Air meter says 8.2 on a 6 percent target, tell the driver to sit tight while I run it again.
Also heard as
- pressure meter
- air pot
- roll-a-meter
- air test
Related terms
Air entrainment
Deliberately building billions of microscopic air bubbles into concrete so it survives freezing and thawing.
Slump
How far a cone-shaped sample of fresh concrete sags, the standard field measure of consistency.
Cylinder
A cast concrete test specimen, usually 4 by 8 in or 6 by 12 in, crushed to measure compressive strength.