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(SW2) BIBS MAR2024 > Concrete(BB-CH6) > Flashcards

Concrete(BB-CH6) Flashcards

1
Q

(True or False) Concrete has high ability to resist stretching, bending, and twisting.

A

false

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2
Q

What principle factor controls the strength of concrete?

A

water cement ratio

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3
Q

(True or False) The major factor controlling the durability of concrete is its strength.

A

true

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4
Q

If more water is added to a concrete mix than is needed to hydrate the cement, the
concrete becomes less_______.

A

watertight

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5
Q

The production of good concrete is impossible unless good quality materials are used in the
mix, and this mix is properly_______.

A

worked and cured

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6
Q

Portland cement is manufactured from finely ground limestone mixed with which of the
following materials?

A

any of the above

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7
Q

For highway construction, Type III Portland cement is sometimes preferred to Type I
because Type III has which of the following characteristics?

A

shorter curing time

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8
Q

What type of cement was developed for use in areas subject to severe frost and ice
conditions?

A

air entrained

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9
Q

(True or False) Aggregate is the material combined with cement and water to make
concrete.

A

true

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10
Q

Concrete is denser and stronger when which of the following conditions is met?

A

all voids are filled

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11
Q

(True or False) When performing a sieve analysis of aggregate, you should determine the
percentage of material retained on the sieve.

A

true

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12
Q

(True or False) To prevent aggregate from segregating during stockpiling, you should build
up piles in layers by dumping successive loads alongside each other.

A

true

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13
Q

In concrete, how is laitance produced?

A

cement is hydrated with excess water

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14
Q

The proportion of air-entraining agent added to a concrete mix should fall within what
range?

A

3-7%

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15
Q

(True or False) The accepted use for retarders is to increase the rate of hydration.

A

false

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16
Q

What is the main reason to store cement in a dry place?

A

To prevent it from setting too slowly and producing weak concrete

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17
Q

When storing sacks of cement in a warehouse, what is the main reason to stack them close
together?

A

To restrict the circulation of air between them

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18
Q

Before using warehouse-packed cement, what should you do to make it lump free?

A

roll the sacks around

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19
Q

(True or False) In a field mix, the number of gallons of water per sack of cement must be
increased to allow for the saturated surface-dry condition of the sand.

A

false

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20
Q

When available aggregate is 1 1/2 inches, what rule of thumb should you use to calculate
materials required for a proper concrete mix?

A

rule 42

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21
Q

For each layer of concrete placed in a mold for a slump test, how many times should you
rod the mold?

A

25

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22
Q

After completing a concrete slump test, you tap the side of the mix and the concrete
crumbles apart. What condition exists?

A

oversanded mix

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23
Q

The rated capacity of a concrete mixing machine is determined by what factor?

A

The cubic feet of the mixed concrete

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24
Q

(True or False) In cement batch-plant operations, the aggregate must pass through a
weigh box before being discharged into the mixer.

A

true

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25
Q

In an 11-S concrete mixer, what maximum size aggregate can you use?

A

3 in

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26
Q

In an 11-S concrete mixer, when should water be added to the mix?

A

After all the dry ingredients have been added

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27
Q

You are to charge the skip of an 11-S concrete mixer. In what order should you add the dry
ingredients?

A

aggregate, cemend, sand

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28
Q

When using a large mixing machine, what minimum time should you mix 2 1/3 cubic yards
of concrete?

A

2 min 15 sec

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29
Q

It is now 12 noon and you just finished placing concrete. You should make sure the inside
of the mixing drum is cleaned no later than?

A

1330

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30
Q

When cleaning a mixing drum, you should place the coarse aggregate in the drum and turn
for how long?

A

5 min

31
Q

When concrete must be discharged more than 4 feet above the level of placement, why
should it be dumped into an elephant trunk?

A

to reduce segregation

32
Q

It is now 12 noon and you begin mixing concrete in a mixing drum. The concrete should be
dumped no later than what time?

A

1330

33
Q

What type of concrete mixer can mix concrete en route to the jobsite?

A

transit mix truck

34
Q

In building construction, what is the most common type of forming material?

A

wood

35
Q

What type of joint should you use to make watertight concrete forms?

A

tongue and groove

36
Q

The hydrostatic head exerted on forms during concrete-placing operations normally
continues for what maximum time?

A

1 1/2 hr

37
Q

(True or False) Footings for any foundation system should always be placed below the
frost line.

A

true

38
Q

An exterior wall that serves as an enclosure and also transmits structural loads to the
foundation is called

A

both a and b

39
Q

Which of the following phrases best defines the term “keyway” in a concrete footer?

A

The indentation in the center of the footer

40
Q

Horizontal form members that tie prefabricated panels together are called_______.

A

walers

41
Q

(True or False) Braces are not part of concrete form design and provide no additional
strength.

A

true

42
Q

What type of form-tying device is used with cone nuts?

A

tie rod

43
Q

When constructing stair forms, you should extend the platform what approximate distance
past the sides?

A

12 in

44
Q

Of the following, which is the best bond breaking agent to use on steel forms?

A

marine engine oil

45
Q

(True or False) A light film of rust or mill scale is acceptable on rebar.

A

true

46
Q

Which of the following rebar ties should you use when a finished mat is to be lifted by
crane?

A

saddle tie with a twist

47
Q

When a column assembly of reinforcing bars is raised into place, the reinforcing steel is tied
to the column form at intervals of

A

5 ft

48
Q

(True or False) In footing construction, stones may be used instead of steel supports under
reinforcing bars.

A

true

49
Q

A joint that separates a floor slab from a column is called

A

isolation joint

50
Q

A joint that allows the transfer of part of the load from one structural element to another
through the use of keys or dowels is called a

A

construction joint

51
Q

What type of blade is normally used to cut seasoned concrete?

A

diamond

52
Q

(True or False) High quality concrete requires both a well designed mix and good placing
procedures.

A

true

53
Q

What is the maximum distance concrete should be dropped from a chute?

A

4 ft

54
Q

When placing concrete on a slope, you should start at what position?

A

bottom only

55
Q

What is the best tool for compacting concrete?

A

mechanical vibrator

56
Q

(True or False) It is permissible to use a mechanical vibrator to move concrete in forms.

A

false

57
Q

Which of the following procedures is used to bring a concrete surface to the required
elevation?

A

screeding

58
Q

The speed at which a vibrating screed is pulled across concrete directly depends on which
of the following factors?

A

the slump of the concrete

59
Q

(True or False) Troweling a vibrator screed finished floor slab is usually delayed because
of the slow setup time needed for the concrete mix.

A

false

60
Q

Which of the following finishing tools gives concrete a smooth, dense, finished surface?

A

steel trowel

61
Q

Which of the following processes produces a nonskid or rough concrete surface?

A

brooming

62
Q

Concrete made with ordinary cement is generally cured for what minimum period?

A

3 days

63
Q

(True or False) When curing flat surfaces, ponding allows the concrete to maintain a
uniform temperature.

A

true

64
Q

Which of the following materials is the best insulator?

A

straw

65
Q

When plastic is used in the concrete curing process, what is the minimum overlap for
adjacent sheets?

A

12 in

66
Q

When patching concrete, you should apply mortar in layers NOT exceeding what maximum
thickness?

A

1/2 in

67
Q

Of the following surfaces, which is best for precast concrete?

A

concrete

68
Q

At what point in concrete casting should the bond-breaking agent be applied to a casting
surface?

A

after edge forms are placed

69
Q

What is the simplest method for pickup of small cast panels?

A

2 point

70
Q

What is the most common type of brace used in tilt-up concrete construction?

A

tubular

71
Q

(True or False) Because of their flexibility and tendency to stretch, cable braces are
unsuitable for most projects.

A

true

72
Q

In cast concrete, sand streaking is caused by

A

escape of moisture from loose forms

73
Q

Compared to cast-in-place panels, precast panels have what main advantage(s)?

A

all of the above

(SW2) BIBS MAR2024 (11 decks)

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