Test Method C173: Air Content of Freshly Mixed Concrete by the Volumetric Method Flashcards
The volumetric method of determining air content of concrete can be used on concrete containing what types of aggregate?
All types of aggregate
What are the requirements for the tamping rod used in the test method?
Round, straight 5/8 [16 mm] +- 1/16 in. [2 mm] diameter rod at least 5 in. [300 mm] greater in length than the depth of the bowl being used, with the tamping end rounded to a hemispherical tip of the same diameter, made of steel, high-density polyethylene, or other plastic of equal or greater abrasion resistance.
What are the requirements for the strike-off bar used in this test method?
Flat, straight steel bar at least 1/8 by 3/4 by 12 in. [3 by 20 by 300 mm] or a 4.4 flat, straight high-density polyethylene bar, or other plastic of equal or greater abrasion resistance, at least 1/4 by 3/4 by 23 in [6 by 30 by 300 mm].
What is the approx volume of the measuring cup used to add water to the air meter, in relation to the volume of the air meter bowl?
1% +/- 0.04%
What type of alcohol and concentration must be used in this test method?
Isopropyl, 70% by volume (65% by weight)
A mallet weighing ___ must be used to tap the sides of the bowl after rodding each layer.
1.25 +/- 0.5 lb
The sample of concrete used in this test method must be obtained in accordance with what ASTM Standard?
C172
The max size aggregate allowed in this test method is ___.
1.5 inches
If the concrete sample contains aggregate larger than that allowed for this test, the sample must be ____.
Wet sieved over a 1 inch sieve
When filling the bowl of the air meter, the concrete must be placed in ___ layers of equal depth.
2
What is the specified number of strokes required when rodding each layer of concrete?
25
It is necessary to tap the sides of the bowl after each layer has been rodded. T/F
True
The initial quantity of water and alcohol added to the air meter can be poured directly in to the neck of the top section of the air meter. T/F
False, the funnel must be used
Upon final filling of the air meter with water, what part of the liquid level should be adjusted to the zero mark on the meter?
Bottom of the meniscus
How long should the air meter be inverted and agitated?
No more than 5 seconds at a time, but must be repeated for a minimum of 45 seconds to free concrete from the base.
How many times does the rolling operation occur?
A minimum of 2, max of 3
Why is the isopropyl alcohol added to the meter?
To dispel any foam that may be on the surface of the water.
The direct reading of the final liquid level in the neck of the air meter, is estimated to the nearest ___.
.25%
If the air content is greater than the 9% range of the meter, ___________.
Calibrated cups of water are added to ring the liquid level within the graduated range.
In order for an initial meter reading to be valid, the meter must not be leaking, the liquid level must stabilize within 6 minutes, and the foam on the surface of the liquid must not be greater than 2 full percent divisions. T/F
True
If less than 2.5 pints of alcohol are used, the air content is always indicated by the initial meter reading. T/F
False, if the air content is more than 9%, the number of cups of water introduced into the meter to bring the liquid level within the graduated range must be added
If more than 2.5 pints of alcohol are used, the final meter reading is always adjusted using ____.
A correction factor
When large amounts of alcohol are used, the direct reading will tend to indicate a _____ air content.
Higher
At the end of the procedure, the air meter is _____.
Disassembled and its contents examined
If portions of undisturbed concrete are found in the air meter at the end of the test, ____.
The test is invalid
