ASTM C173/C173M - Air Content of Freshly Mixed Concrete by the Volumetric Method Flashcards
Volumetric method covers determination of the air content of freshly mixed concrete containing what types of aggregates?
All types of aggregates, whether it be dense, cellular, or lightweight
Volumetric method measures the air contained in the _______ fraction of the concrete, but is not affected by air present in porous aggregate particles.
Mortar
This test method requires the addition of _______ when the meter is initially being filled with water, so that after the first or subsequent rollings little or no _____ collects in the neck of the top section of the meter.
Isopropyl alcohol
Foam
After the initial rolling of the meter, If more foam is present than that equivalent to ___% air above the water, the test is declared _______ and must be repeated with a larger portion/quantity of _______
2%
Invalid
Alcohol
Air content of hardened concrete may be _______ or _______ than that determined by this test method.
Higher or Lower
Measuring bowl must have a diameter that is equal to 1 to 1.25 times the ______________
Height of the measuring bowl
TRUE or FALSE:
Measuring bowl shall not have a capacity of less than ___ L [ ___ cu. ft]
- 0 Liters
0. 075 Cubic Feet
Top section of the meter shall have a capacity at least ___ % larger than the measuring bowl
20%
Top section of the meter shall be equipped with a transparent scale, graduated in increments not greater than ___%, from ___ at the top, to ___, or more, of the volume of the measuring bowl.
.5%
0% at the top
9%, or more
Gradations of the scale shall be accurate to ___ % by volume of the measuring bowl.
0.1%
Funnel shall be long enough to extend to a point just _____ the bottom of the top section.
Above
Tamping rod to be ___ diameter, and be at least ___ inches greater than the depth of the measuring bowl, but not be greater than ___ inches long.
5/8” diameter
4 inches greater
24 inches long
Strike-off bar can be steel or plastic.
Steel strike-off bar dimensions are (at least):
__ inches thick, __ inches wide & __ inches long
Plastic strike-off bar dimensions are:
__ inches thick, __ inches wide & __ inches long
Steel = 1/8" x 3/4" x 12" long Plastic = 1/4" x 3/4" x 12" long
TRUE or FALSE:
Tamping rod shall have the tamping end, or both ends, rounded to a hemispherical tip of the same diameter as the rod.
True
Calibrated cut to have a capacity of, or being graduated in increments equal to ___ % of the volume of the measuring bowl of the air meter
1.00% [+/-.04%]
When is the ONLY time the calibrated cup is needed, and why?
When the concretes air content exceeds 9%.
The calibrated cup of water is used to bring the water level back into range of the scale.
Measuring vessel for alcohol to have a minimum capacity of at least __ pint
1 pt (500 mL)
Rubber syringe having the capacity for at least __ ounces
2 oz (50 mL)
Pouring vessel for water shall have a capacity of approximately __ qt.
1 qt (1 L)
Mallet to have a mass of _______
1.25 lbs. [+/-.5 lbs]
Calibrate the meter _______ and ________, or whenever there is a reason to suspect damage or deformation.
Initially
Annually
Obtain sample of freshly mixed concrete in accordance with practice ASTM _____
C172
Fill measuring bowl with concrete in ____ layers of approximately equal volume.
Rod each layer ____ times.
2 layers
25 times
After each layer has been rodded, tap the sides of the bowl with a mallet ___ to ___ times.
10 to 15 times
After tapping the sides of the bowl after the final layer, a slight excess of concrete of ___ mm [___ in] or less is acceptable.
TRUE or FALSE:
Add or remove a representative sample of concrete if necessary to obtain the required amount of concrete.
3 mm [ 1/8 inch ]
TRUE
Wet inside of the top section, including gasket, prior to attaching to bottom section.
Insert ______.
Add at least ___ L [___ pt] of water followed by selected amount of alcohol.
Funnel
0.5 L [ 1 pt ]
Do you add or subtract the Alcohol Correction Factor from the final air reading?
Subtract
Alcohol Correction Factors:
2 pints or less = 0% correction
3 pints = ________ correction
4 pints = ________ correction
5 pints = ________ correction
3 pints = 0.25% alcohol correction factor
4 pints = 0.50% alcohol correction factor
5 pints = 0.75% alcohol correction factor
If air content exceeds 9% air, add water using the _________ until water is visible in the graduated range.
Calibrated cup
which is equal to 1.00 +/-.04% of the measuring bowl
The number of calibrated cups of water will be _____ to the final air reading.
Added
After alcohol has been added, fill the graduated scale up with more ______.
How much do you add?
What are the next three steps?
Water.
Add enough water to get it close to the 0% mark on the graduated scale
1 - Remove the funnel.
2 - Use the rubber syringe to add water to the point that the bottom of the meniscus is level with the 0% mark on the graduated scale.
3 - Place the watertight cap
After watertight cap has been placed, invert the meter and shake horizontally in ___ second intervals for the next ___ seconds. This process is meant to free the concrete from the measuring bowl.
5 second intervals
45 seconds
After inverting meter for 45 seconds, tilt the meter ___ degrees and rotate the meter with hand 1/4 to 1/2 turns back and forth, occasionally turning the bowl 1/3 turns.
How long does this need to be done?
45 degrees
1 minute
After rolling the meter for 1 minute, set the meter upright and remove the ________.
Then, allow the pressure to ________.
The liquid level is considered stable when it does not change more than ___ % air within _____ minutes.
Watertight cap.
Stabilize
0.25% air
2 minutes
After initial air % has been recorded, what is the next step?
Place the watertight cap back on and repeat the rolling process for 1 more minute
After second rolling of the meter has been completed, remove the watertight cap and allow the pressure to stabilize for ____ minutes.
Once the air stabilizes, and if it is within ___% of the initial reading, read the bottom of the meniscus to the nearest ___% and record this as your final reading.
2 minutes
0.25%
If after the second rolling, the pressure DOES NOT stabilize within ___ minutes, you need to close the watertight cap and roll for a third and final time.
If the pressure stabilizes within 2 minutes, read the bottom of the meniscus to the nearest _____%.
2 minutes
0.25%
After the third rolling, if the air does not stabilize (after 6 total minutes), _______ the test and start a new one using a new sample of concrete.
Discard
If there is more foam than that equivalent to 2 full percent air content over the liquid level, _______ the test and start a new one using a larger addition of ________.
Discard
Alcohol
