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ACI > ACI Technical > Flashcards

ACI Technical Flashcards

1
Q

A 6 by 12 in cylinder mold can be used for concrete containing aggregate with particles not exceeding
_____ in size, without the need for wet sieving the concrete.

A

2 inch

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2
Q

According to ASTM C1064, what is one reason to take the temperature of concrete?

A

Verify conformance to a specified requirement for temperature of concrete

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3
Q

After completing the strike-off procedure, what must be dont before weighing the measure and sample?

A

Clean off any excess concrete

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4
Q

After consolidation of the final layer, an excess of concrete ___ above the top of the measure is considered optimum.

A

1/8 inch

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5
Q

After molding test specimens, you should wait two hours before moving them to the location of initial storage. True or False?

A

False, the specimens must be moved within 15 minutes

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6
Q

After rodding each layer, what should be done to the measure before adding another layer of concrete?

A

Tap the sides of the measure smartly 10 to 15 times with the mallet

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7
Q

After final rodding, the sides of the slump mold should be tapped lightly with the tamping rod. True or False?

A

False

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8
Q

After the temperature of the concrete is read, what is required?

A

Reporting of temperature, record it, sun, wind, contamination

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9
Q

Air meter bowls used for this test must conform to ASTM ___ and be calibrated for volume according to ASTM ___.

A

C231, C29

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10
Q

The approximate concrete depth (in vertical distance) after placing the first layer is ___, and the second layer is ___.

A

2 5/8 inch, 6 1/8 inch

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11
Q

ASTM Method gives standardized requirements for ___, ___, ___, and ___, of test specimens.

A

making, curing, protecting, transporting

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12
Q

At the end of the procedure, the air meter is ___.

A

Disassembled and its contents examined

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13
Q

The composite sample for a paving mixer must represent a minimum of ___ different portions of the batch of concrete taken from the pile after discharge.

A

5

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14
Q

A composite sample of concrete is required even if the only purpose for obtaining the sample is to determine temperature. True or False

A

False

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14
Q

The composite samples from a truck mixer must be obtained from the portion from the ___ portion of the batch

A

middle

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14
Q

Concrete mixtures with specified strengths of 6000 psi or greater shall have initial curing temperature between ___.

A

68 and 78 degress F

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14
Q

The concrete sample must be obtained in accordance with what ASTM method?

A

C172

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15
Q

The concrete sample must be protected from contamination and ___.

A

Rapid evaporation

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15
Q

Concrete samples from a truck mixer must be obtained before any water or admixture are added to the mixer at the job site. True or False?

A

False

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16
Q

The container for obtaining the concrete sample used in this procedure can be a ___, ___, or ___.

A

Metal pan, wheelbarrow, flat, clean nonabsorbent mixing board

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17
Q

Cylinders made for the purpose of determining when a structure may be put into service shall be removed from the mold ___.

A

At the time of the removal of formwork

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18
Q

Cylinders that are to be field cured are stored ___ and protected ___.

A

In or on the structure as near to the point of deposit of the concrete represented as possible; In as near as possible the same way as the formed work

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19
Q

The diameter of the tamping rod used in the test method is ___.

A

5/8 inch except 4” x 8” cylinders

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20
Q

The direct reading of the final liquid level in the neck of the air meter, is estimated to the nearest ___.

A

0.25 %

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21
Q

During transportation, test specimens must be protected from damage due to ___, ___, and ___.

A

Jarring, freezing temperatures, moisture loss

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22
Q

Each layer should fill approximately ___ the volume of the mold

A

One-third

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23
Q

Field Curing is the curing method used when test specimens are to be used for ___.

A

Determination of whether the structure is capable of being put into service; Comparison with standard cured specimens test results or with results from various in-place test methods; Adequacy of curing and protection of concrete in the Structure, or Form or shoring removal time requirements.

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24
Q

For a measure of 0.5 ft^3 [14 L], what is the required number of strokes of the tamping rof for consolidation of each layer?

A

25

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25
Q

For concrete with a slump less than 1 inch [25 mm], the test specimens must be consolidated by ___.

A

Vibration

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26
Q

For cylinders with a diameter of 6 inch [150 mm] or greater, the tamping rod must be a round, straight steel rod with diameter of ___.

A

5/8 +- 1/16 inch [16 mm +-2mm] 4 inch longer than cylinder. 24 inch maximum

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27
Q

For use in the slump test, the end of both ends of the tamping rod must be ___.

A

Rounded to a hemispherical tip

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28
Q

The height of the slump mold is ___.

A

12 inches [300 mm]

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29
Q

How deep should the tamping rod penetrate into each layer?

A

Rod each layer throughout its depth; on the second and final layers, the rod should penetrate into the previous layer approximately 1 inch [25 mm]

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30
Q

How long must the temperature measuring device remain in the freshly mixed concrete?

A

At least 2 minutes but not more than 5 minutes

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31
Q

How long should the air meter be inverted and agitated?

A

No more than five seconds at a time but must be repeated for a minimum of 45 seconds to free concrete from the base

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32
Q

How many times does the rolling operation occur?

A

A minimum of 2, a maximum of 3

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33
Q

How much time is allowed for lifting the slump mold?

A

5 +- 2 seconds

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34
Q

How much time is allowed to conduct the slump test from beginning to completion?

A

2 1/2 minutes

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35
Q

If, after consolidation of the final layer, the concrete level is 1/2 in. [13 mm] above the top of the measure, what should be done?

A

Remove a representative portion of the excess concrete with a trowel or scoop to 1/8” optimum

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36
Q

If less than 2.5 pints of alcohol are used, the air content is always indicated by the final meter reading. True or False?

A

False, if the air content is more than 9%, the number of calibrated cups of water introduced into the meter to bring the liquid level within the graduated range must be added

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37
Q

If more than 2.5 pints of alcohol are used, the final meter reading is always adjusted using ___.

A

A correction factor

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38
Q

If portions of undisturbed concrete are found in the air meter at the end of the test, ___.

A

The test is invalid

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39
Q

If rodding is the method of consolidation being used, the measure must be filled in how many layers?

A

3

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40
Q

If the air content is greater than the 9% range of the meter, ___.

A

Calibrated cups of water are added to bring the liquid level within the graduated range

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41
Q

if the concrete contains aggregate larger than the maximum allowed for this test, the sample must be

A

Wet sieved over a 1 1/2 inch [37.5 mm] sieve

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42
Q

If the concrete is to be consolidated by vibration, a standard 4 by 8 in. [100 mm by 200 mm] cylinder mold must be filled in ___ equal layers.

A

2

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43
Q

If the concrete sample contains aggregate larger than that allowed for this test, the sample must be ___.

A

Wet seived over a 1 in. [25 mm] sieve

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44
Q

If the concrete sample is to be consolidated by rodding, the measure is filled in ___ layers.

A

3 equal

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45
Q

If the concrete sample is to be consolidated by vibration, the measure is filled in ___ layers.

A

2 equal

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46
Q

If vibration is the method of consolidation, the measure must be filled in ___ approximately equal layers

A

2

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47
Q

The initial quantity of water and alcohol added to the air meter can be poured directly into the neck of the top section of the air meter. True or false?

A

False; the funnel must be used

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48
Q

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. True or false?

A

True

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49
Q

In rodding the sample, how deep should the rod penetrate each layer?

A

Rod bottom to full depth; rod second and final layer penetrating the previous layer about 1 in. [25 mm]

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50
Q

The interior surface of the slump mold is allowed to have minor irregularities. True or false?

A

False

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51
Q

It is necessary to tap the sides of the bowl after each layer has been rodded. True or false?

A

True

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52
Q

A mallet weighing ___ must be used to tap the sides of the bowl after rodding each layer.

A

1.25 +- 0.50 lb [600 +-200g]

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53
Q

The maximum allowable time between ontaining the first and final portions of the composite sample is ___ minutes.

A

15

54
Q

The maximum elapsed time allowed between obtaining the final portion of the composite sample and the beginning of the test for slump, temperature, and air content is ___ minutes.

A

5

55
Q

The maximum size aggregate allowed for this test method is ___.

A

2 in. [50 mm] in 6x12” cylinder

56
Q

The maximum size aggregate allowed in this test method is ___.

A

1 1/2 in. [37.5 mm] in pressure meter

57
Q

A maximum temperature of freshly mixed concrete is specified in ASTM C1064. True or false?

A

False

58
Q

The measurement for slump is made from the top of the mold to what point of the concrete specimen?

A

The displaced original center of the top surface of the specimen

59
Q

Measures other than air meter bowls used for this test must conform to ASTM ___.

A

C29

60
Q

The minimum frequency of an internal vibrator used in this procedure is ___.

A

9000 vibrations per minute [150 Hz]

61
Q

The minimum size sample for making strength test specimens is ___.

A

28 L [1 ft^3]

62
Q

The mold for making the slump test is in the shape of ___.

A

The frustum of a cone

63
Q

The molding of strength test specimens shall begin within ___ minutes after fabricating the composite samples.

A

15

64
Q

The outside diameter or side dimension of the vibrating element must be at least ___ but not greater than ___.

A

0.75 in. [19 mm], 1.50 in. [38 mm]

65
Q

A plastic container can be used for the measure in this method. True or false?

A

False, measure must be steel or another suitable metal

66
Q

Portion of a composite sample shall be thoroughly remixed before beginning tests on the sample. True or false?

A

True

67
Q

The pressure method of determining air content can be used on concrete containing ___ ___ aggregate.

A

Relatively Dense
Normal Weight

68
Q

The pressure method of determining air content cannot be used on concrete containing the following types of aggregates, ___, ___, ___.

A

Lightweight, air-cooled blast furnace slag, or aggregates of high porosity

69
Q

Prior to lifting the mold, concrete must be removed from ___.

A

The area surrounding the base of the mold

70
Q

The sample of concrete for use in making the slump test must be obtained in accordance with ASTM Standard ___.

A

C172, Standard practice for sampling freshly mixed concrete

71
Q

The sample of concrete used for temperature determination must be rodded 25 times. True or false?

A

False

72
Q

The sample of concrete used for this test is to be obtained in accordance with what ASTM standard?

A

C172

73
Q

The sample of concrete used in molding test specimens must be obtained in accordance with what ASTM standard?

A

C172

74
Q

The sample of concrete used in this test method must be obtained in accordance with what ASTM Standard?

A

C172

75
Q

Sampling by this method is required when tests are to be made to determine ___ with specification requirements.

A

Compliance

76
Q

The sensor of the temperature measuring device shall be submerged a minimum of ___ in. [___ mm] into the freshly mixed concrete.

A

3 inches [75 mm]

77
Q

The slump mold is filled in ___ layers.

A

3

78
Q

The slump mold should be in a dry condition before beginning the test. True or False?

A

False

79
Q

The slump of the concrete is measured and reported to the nearest ___.

A

1/4 in [5 mm]

80
Q

The slump test is applicable to plastic concrete with a maximum size aggregate of ___.

A

1.5 in. (37.5 mm]

81
Q

Specimens shall not be transported until ___ after final set.

A

8h

82
Q

Standard Curing is the curing method used when test specimens are to be used for ___.

A

Acceptance testing for specified strength, checking the adequacy of mixture proportions for strength, quality control

83
Q

The supporting surface on which specimens are stored shall be level within ___.

A

1/4 in. per ft. [20 mm per m]

84
Q

The surface on which the slump mold will be placed must be ___.

A

Flat, level, moist, nonabsorbent, and free of vibration

85
Q

The temperature and moisture environment for field cured cylinders must be ___.

A

The same as the structural work

86
Q

The temperature measuring device shall be calibrated ___, or whenever there is a question of ___.

A

Annually, accuracy

87
Q

The temperature measuring device shall have a capacity of measuring temperature of freshly mixed concrete to +- ___ degrees F [+- ___C] throughout a range of ___.

A

1 degree F [0.2 C], 30 degrees F to 120 F [0 C to 50 C]

88
Q

The temperature of concrete is reported to the nearest ___ degrees F [___ C].

A

1 degree F [0.5 C]

89
Q

The temperature of concrete may be measured in a wall form. True or False

A

True

90
Q

The temperature of concrete may be measured in a wheelbarrow. True or False?

A

True

91
Q

This method covers sampling from five types of mixtures which are ___, ___, ___, and ___.

A

Stationary mixers, paving mixers, revolving drum mixers, open top mixers, and continuous mixers

92
Q

Transportation time shall not exceed ___. minutes

A

4 hours

93
Q

Upon completion of initial curing, the test specimens may be left in their molds and sealed in plastic bags. True or False?

A

False; specimens are to be demolded and placed in water storage tanks or moist rooms with free water at a temperature of 73.5 +- 3.5 degrees F [23 +- 2.0 C]

94
Q

Upon final filling of the air meter with water, what part of the liquid level should be adjusted to the zero mark on meter?

A

Bottom of the meniscus

95
Q

Up to 48 hours after molding, test specimens that are to be standard cured shall be stored in a temperature range between ___ to ___.

A

60 and 80 degrees F [16 to 27 C]

96
Q

Vibration of the concrete sample is not allowed when the slump of concrete exceeds ___.

A

3 in. [75 mm] Except for cylinders and beams

97
Q

The volumetric method of determining air content of concrete can be used on concrete containing what types of aggregate?

A

All types of aggregate

98
Q

What are the required characteristics of the tamping rod used in this test method?

A

Round, straight steel rod, with a 16 mm [5/8 in/] +/- mm [1/16 in.] diameter, length at least 100 mm [4 in.] greater than the depth of the measuring bowl, but not greater than 600 mm [24 in.] in overall length, with the tamping end rounded to a hemispherical tip of the same diameter as the rod. (All but 4x8” cylinder)

99
Q

What are the requirements for the strike-off bar used in this test method?

A

Flat, straight steel bar at least 1/8 by 3/4 by 12 in. [3 by 20 by 300 mm] or a flat, straight high-density polyethylene bar, or other plastic of equal or greater abrasion resistance, at least 1/4 by 3/4 by 23in. [6 by 30 by 300mm]

100
Q

What are the requirements for the tampinf rod used in the test method?

A

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. (At volumetric meter only.)

101
Q

What is the approximate volume of the measuring cup used to add water to the air meter, in relation to the volume of the air meter bowl?

A

1.00% +- 0.04%

102
Q

What is the minimum allowable capacity of the measuring bowl used in this test method?

A

6 L [0.20 ft^3]

103
Q

What is the minimum thickness for a glass or acrylic strike-off plate?

A

1/2in. [12mm]

104
Q

What is the minimum thickness of a metal strike-off plate?

A

1/4 in. [6 mm]

105
Q

What is the required minimum frequency of the vibrator used in this test method?

A

9000 vibrations per minute

106
Q

What is the required shape of the tamping end of the rod?

A

Rounded to a hemispherical tip

107
Q

What is the specified number of rodding’s for each layer?

A

25

108
Q

What is the specified number of strokes required when rodding each layer of concrete?

A

25

109
Q

What is the specified weight of the mallet required for this test method when the measuring bowl has the capacity of 1 ft^3 or less?

A

2.25 +-0.50 lb.

110
Q

What is the specified weight of the mallet used on measures that are 0.5 ft^3 [14 L] or smaller?

A

1.25 +-0.50 lb. [600 +- 200g]

111
Q

What method of consolidation must be used when the slump is greater than 3 in. [75 mm]

A

Rodding

112
Q

What method of consolidation must be used when the slump is less than 1 in. (25 mm)?

A

Vibration

113
Q

What must be done if the concrete drops below the top of the slump mold while the top layer is being rodded?

A

Add additional concrete to keep an excess of concrete above the top of the mold at all times

114
Q

What must be done if there is an excessive amount of concrete in measure following consolidation of the final layer?

A

Remove a representative quantity of concrete with the scoop or trowel before the strike off

115
Q

What must be done if there is a slight deficiency in the quantity of concrete in the measure of consolidation of final layer?

A

Add a quantity of representative concrete before strike off

116
Q

What must be done to the concrete surrounding the temperature measuring device after the device is submerged in the fresh concrete.

A

Gently press the concrete around the temperature measuring device at the surface of the concrete

117
Q

What must be done to the sample container prior to sampling the concrete?

A

Dampen (with water)

118
Q

What tools may be used to strike off the top surface of the concrete following consolidation of the final layer?

A

A strike-off bar; a metal, glass, or acrylic plate. (Air pressure only)

119
Q

What type of alcohol and concentration must be used in this test method?

A

Isopropyl, 70% by volume (65% by weight)

120
Q

When consolidating a flexural strength test specimen by rodding, rod one stroke for each ___ of top surface area

A

2 in^2 [14 cm^2]

121
Q

When consolidating the concrete by vibration, how many times should the vibrator be inserted into each layer?

A

3

122
Q

When filling the bowl of the air meter, the concrete must be placed in ___ layers of equal depth.

A

2 when vibrating

123
Q

When internal vibration is used to be consolidate a standard flexural strength test specimen, the technician should insert the vibrator at intervals not exceeding ___ along the center line of the beam.

A

6 in. [150 mm]

124
Q

When large amounts of alcohol are used, the direct reading will tend to indicate a ___ air content.

A

Higher

125
Q

When raising the slump mold, it should not be rotated or twisted. True or False?

A

True

126
Q

When rodding a standard 6 by 12 in [150 mm by 300 mm] cylinder, each layer must be rodded ___ times.

A

25

127
Q

When rodding a standard 6 by 12 in. [150 mm by 300 mm] cylinder, the tamping rod should penetrate into the underlying layer by about ___.

A

1 in. [25 mm]

128
Q

When rodding the bottom layer, the tamping rod must be ___ to uniformly distribute the strokes.

A

Slightly inclined for slump

129
Q

When rodding the concrete sample, what is the specified number of strokes required for each layer?

A

25

130
Q

When rodding the middle and the top layers, the tamping rod should penetrate into the layer below approximately ___.

A

1 in. [25 mm]

131
Q

When sampling from a revolving drum truck mixer, concrete must be sampled at a minimum of ___ regularly spaced intervals during discharge of the middle portion of this batch.

A

2

132
Q

When sampling from a stationary mixer, the batch must be sampled at ___ or more regularly spaced intervals during discharge of the middle portion of the batch.

A

2

133
Q

When strength specimens are to be made, what three other tests must be made?

A

Slump, air content, temperature

134
Q

When the concrete contains aggregate larger than the allowed for the slump test, the large aggregate must be ___.

A

Removed by wet sieving the sample over 1.5 in [37.5 mm] sieve

135
Q

When thee concrete contains aggregate larger than that permitted for a particular test method, the sample of concrete must be ___, ___ before making the test.

A

Wet seived

136
Q

When using an internal vibrator to consolidate a 6 by 12 in. [150 mm by 300 mm] compressive strength test specimen, the vibrator must be inserted at ___ different points for each layer.

A

2

137
Q

Why is the isopropyl alcohol added to the water?

A

To dispel any foam that may be on the surface of the water

ACI (1 decks)

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