ASTM C173/C173M - Air Content of Freshly Mixed Concrete by the Volumetric Method

Question 1

Volumetric method covers determination of the air content of freshly mixed concrete containing what types of aggregates?

Answer 1

All types of aggregates, whether it be dense, cellular, or lightweight

Question 2

Volumetric method measures the air contained in the _______ fraction of the concrete, but is not affected by air present in porous aggregate particles.

Answer 2

Mortar

Question 3

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.

Answer 3

Isopropyl alcohol

Foam

Question 4

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 _______

Answer 4

2%
Invalid
Alcohol

Question 5

Air content of hardened concrete may be _______ or _______ than that determined by this test method.

Answer 5

Higher or Lower

Question 6

Measuring bowl must have a diameter that is equal to 1 to 1.25 times the ______________

Answer 6

Height of the measuring bowl

Question 7

TRUE or FALSE:

Measuring bowl shall not have a capacity of less than ___ L [ ___ cu. ft]

Answer 7

2. 0 Liters

0. 075 Cubic Feet

Question 8

Top section of the meter shall have a capacity at least ___ % larger than the measuring bowl

Answer 8

20%

Question 9

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.

Answer 9

.5%
0% at the top
9%, or more

Question 10

Gradations of the scale shall be accurate to ___ % by volume of the measuring bowl.

Answer 10

0.1%

Question 11

Funnel shall be long enough to extend to a point just _____ the bottom of the top section.

Answer 11

Above

Question 12

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.

Answer 12

5/8” diameter
4 inches greater
24 inches long

Question 13

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

Answer 13

Steel = 1/8" x 3/4" x 12" long
Plastic = 1/4" x 3/4" x 12" long

Question 14

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.

Answer 14

True

Question 15

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

Answer 15

1.00% [+/-.04%]

Question 16

When is the ONLY time the calibrated cup is needed, and why?

Answer 16

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.

Question 17

Measuring vessel for alcohol to have a minimum capacity of at least __ pint

Answer 17

1 pt (500 mL)

Question 18

Rubber syringe having the capacity for at least __ ounces

Answer 18

2 oz (50 mL)

Question 19

Pouring vessel for water shall have a capacity of approximately __ qt.

Answer 19

1 qt (1 L)

Question 20

Mallet to have a mass of _______

Answer 20

1.25 lbs. [+/-.5 lbs]

Question 21

Calibrate the meter _______ and ________, or whenever there is a reason to suspect damage or deformation.

Answer 21

Initially

Annually

Question 22

Obtain sample of freshly mixed concrete in accordance with practice ASTM _____

Answer 22

C172

Question 23

Fill measuring bowl with concrete in ____ layers of approximately equal volume.
Rod each layer ____ times.

Answer 23

2 layers

25 times

Question 24

After each layer has been rodded, tap the sides of the bowl with a mallet ___ to ___ times.

Answer 24

10 to 15 times

Question 25

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.

Answer 25

3 mm [ 1/8 inch ]

TRUE

Question 26

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.

Answer 26

Funnel

0.5 L [ 1 pt ]

Question 27

Do you add or subtract the Alcohol Correction Factor from the final air reading?

Answer 27

Subtract

Question 28

Alcohol Correction Factors:

2 pints or less = 0% correction
3 pints = ________ correction
4 pints = ________ correction
5 pints = ________ correction

Answer 28

3 pints = 0.25% alcohol correction factor
4 pints = 0.50% alcohol correction factor
5 pints = 0.75% alcohol correction factor

Question 29

If air content exceeds 9% air, add water using the _________ until water is visible in the graduated range.

Answer 29

Calibrated cup

which is equal to 1.00 +/-.04% of the measuring bowl

Question 30

The number of calibrated cups of water will be _____ to the final air reading.

Answer 30

Added

Question 31

After alcohol has been added, fill the graduated scale up with more ______.

How much do you add?

What are the next three steps?

Answer 31

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

Question 32

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.

Answer 32

5 second intervals

45 seconds

Question 33

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?

Answer 33

45 degrees

1 minute

Question 34

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.

Answer 34

Watertight cap.
Stabilize
0.25% air
2 minutes

Question 35

After initial air % has been recorded, what is the next step?

Answer 35

Place the watertight cap back on and repeat the rolling process for 1 more minute

Question 36

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.

Answer 36

2 minutes

0.25%

Question 37

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 _____%.

Answer 37

2 minutes

0.25%

Question 38

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.

Answer 38

Discard

Question 39

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 ________.

Answer 39

Discard

Alcohol