ASTM C231/C231M - Standard Test Method for Air Content of Freshly Mixed Concrete by the Pressure Method Flashcards

1
Q

“This test method is intended for use with concretes and mortars made with relatively _____ aggregates”

A

Dense

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2
Q

TRUE or FALSE
Pressure method testing is not applicable to concretes made with lightweight aggregates, air-cooled blast-furnace slag, or aggregates of high porosity. In those cases, test method C173 should be used.

A

True.

ASTM C231 is intended for concretes and mortars made with relatively dense aggregates.

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3
Q

RODDING or VIBRATION

A - Concrete with slump less than 1”
B - Concrete with slump between 1” and 3”
C - Concrete with slump greater than 3”

A
A = Vibrate
B = Vibrate or Rodding
C = Rodding
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4
Q

If concrete slump is 2”, what method(s) of consolidation could you use?
Considering the method of consolidation you choose, how many layers of equal ______ do you place into the bowl?

A

You can consolidate using either
VIBRATION or RODDING method.

If VIBRATING, 2 layers of equal VOLUME
If RODDING, 3 layers of equal VOLUME

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5
Q

Before adding concrete to the measuring bowl, what must be done?

A

Dampen the bowl

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6
Q

When rodding “each upper layer, allow the rod to penetrate through the layer being rodded and into the layer below approximately ___ mm [ ___ in.]”

A

25 mm [1 in]

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7
Q

How may times should you rod each layer?

A

25

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8
Q

What is the weight of the mallet used with measures of 14 L [0.5 cu. ft.], or smaller?
What is the weight of the mallet used with measures greater than 14 L [0.5 cu. ft.]

A

1.25 lbs, +/-0.5 lbs
(for measures 14 L [0.5 cu. ft.], or smaller)

2.25 lbs, +/-0.5 lbs
(for measures greater than 14 L [0.5 cu. ft.])

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9
Q

When vibrating, “insert the vibrator at ___ different points for each layer of concrete.”

A

3

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10
Q

“In compacting the final layer, the vibrator shall penetrate into the underlying layer approximately
___ mm [ ___ in.]”

A

25 mm [ 1 in]

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11
Q

TRUE or FALSE
After final consolidation, “the measure must NOT contain a substantial excess or deficiency of concrete. An excess of concrete protruding approximately 9 mm [3/8 in.] above the top of the mold is optimum.

A

False

3 mm [ 1/8 in.] is optimum

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12
Q

TRUE or FALSE
Do not let the vibrator to touch, or rest on the bottom of the measure. It’s okay if the vibrator touches the sides of the measure as long as its not held there.

A

False

“do not allow the vibrator to rest on or touch the bottom OR sides of the measure”

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13
Q

For Vibrator information, C231 references C192/C192M

Per ASTM C192/C192M
“Vibrator frequency shall be at least _____ vibrations per minute while the vibrator is operating in the concrete.”

A

9000 vibrations per minute

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14
Q

For Vibrator information, C231 references C192/C192M

Per ASTM C192/C192M
“Diameter of a round vibrator shall be no more than ____ the diameter of the cylinder mold or ____ the width of the beam or prism mold.”

A

1/4 the diameter of a cylinder mold

1/4 the width of the beam or prism mold

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15
Q

Tamping Rod shall be at least 4 inches greater than ________________, but not be greater than ____ in total length.

A

The depth of the measuring bowl.

24” in total length

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16
Q

The tamping rod should have a diameter of ____ ?

A

5/8” (+/- 1/16”)

17
Q

The tamping rod is a round, smooth, straight steel rod. The tamping end, or both ends, should be rounded ___ __ ___________ tip of the same _______ as the rod.

A

TO A HEMISPHERICAL tip of the same DIAMETER as the rod

18
Q

The mallet head is to be made of?
(Note all that apply)

Dense Plastic
Rubber
Wood
Metal
Rawhide
A

Rubber

Rawhide

19
Q

“After consolidation of the concrete, strike off the top surface by sliding the strike-off BAR across the top flange or rim of the measuring bowl with a ______ motion”

A

sawing

20
Q

Steps for using a strike-off PLATE
1 - Cover ____ of the top of the bowl with the plate.
2 - Withdraw the plate using a ________ motion
3 - Cover initial ____ of the top of the bowl
4 - Advance the plate forward using a _______ motion
5 - Incline the plate and perform final strokes with the ____ of the plate to produce a smooth surface

A
1 - two thirds
2 - sawing
3 - two thirds
4 - sawing
5 - edge
21
Q

Strike of BAR to be a flat, straight bar of steel or other suitable metal at least ___ in. thick, ___ in. wide, and ___ in. long

A

1/8” thick [6 mm]
3/4” wide [20 mm]
12” long [300 mm]

22
Q

1 - How thick must a metal strike-off PLATE be?

2 - How thick must a glass or acrylic strike-off PLATE be?

A

1/4” - if metal

1/2” - if glass or acrylic

23
Q

Test procedure for a “Type B” meter:

After you have dampened the cover assembly and have clamped it into place, what are your next 4 steps?

A

1 - close the main air valve
2 - open both petcocks
3 - use the syringe to fill one petcock until water emerges from the opposite petcock
4 - jar the meter

24
Q

Test procedure for a “Type B” meter:

What is the purpose for jarring the meter after water emerges from the opposite petcock as to where you’re filling with the syringe?

A

to expel air that may be trapped

25
Q

Test procedure for a “Type B” meter: TRUE or FALSE

When you are satisfied that all air has been expelled through the petcock after jarring the meter, you need to close both petcocks.

A

False, You close the air bleeder valve

26
Q

Test procedure for a “Type B” meter:

What is the next step after jarring the meter and removing trapped air through the petcock?

A

Close the air bleeder valve on the air chamber

27
Q

Test procedure for a “Type B” meter:

What is the next step after closing the air bleeder valve on the air chamber?

A

Pump air into the air chamber.

28
Q

Test procedure for a “Type B” meter:

You pump air into the air chamber until the gauge hand is on the _______ pressure line?

A

Initial

29
Q

Test procedure for a “Type B” meter: TRUE or FALSE

After you finish pumping air to the initial pressure line, allow a few seconds for the compressed air to cool to normal temperature.

A

True

30
Q

Test procedure for a “Type B” meter:

After pumping in the air, stabilize the gauge hand at the initial pressure line by _______ or _______ air as necessary, then _______ the gauge lightly by hand.

A
  • pumping in
  • bleeding out
  • tapping
31
Q

Test procedure for a “Type B” meter:

Once air has been pumped in and the the gauge hand is stable at the initial pressure line, what are the next 5 steps, in order.

A

1 - close both petcocks
2 - open and hold down the main air valve
3 - strike the side of the meter smartly with the mallet
4 - still holding open the main air valve, tap the gauge lightly to stabilize the gauge hand.
5 - record the percentage of air on the gauge