Super Air Meter
The Super Air Meter or SAM is a modified ASTM C231 Type B Pressure Meter. This meter has been developed at Oklahoma State University. The meter can function in two ways. First, it provides all the same information as a Type B meter, under the same analytical conditions as a conventional pressure meter. After completing the conventional testing the meter is then able to move into a second mode of operation that places the concrete under a series of higher pressures. By understanding how the concrete responds to the series of high pressures the meter can assess properties of the air-void system beyond the air content. The result is a measurement that has been shown to correlate well with the spacing factor measurement from ASTM C457 and freeze-thaw performance data such as ASTM C666.
To run the test concrete is placed and consolidated as if a typical ASTM C231 test is run. However with the Super Air Meter test, the test is run multiple times without releasing the pressure in the bottom bowl. The test takes just over 10 minutes to run and provides immediate information about the air void quality in the fresh concrete. This is especially useful to evaluate a concrete mixture before and after a paver, or a pump and for investigation of concrete mixtures with a number of admixtures.
The meter has been validated with over 50 concrete mixtures with different air entraining agents, water reducers, w/cms, and cement contents. These values are shown below. The SAM number has been plotted versus the spacing factor from an ASTM C 457 test. The SAM number is a value calculated from the pressure curves produced in the test. A spacing factor of 0.008â€� is shown. This value is recommended by ACI 201 as the value needed to produce frost durable concrete. There is almost a linear trend between these two measurements.