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02A - Concrete - Design and Control of Concrete Mixtures Flashcards

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1
Q

What is the minimum thickness of a control joint placed in a 6-inch-thick concrete slab on ground?

A

1 ½ inches (Design and Control of Concrete Mixtures 325
Formula: 1/4th of the depth of the slab.)

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2
Q

Concrete will continue to strengthen with age over time as long as the relative humidity of concrete remains above:

A

80 (Design and Control of Concrete Mixtures Page 274)

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3
Q

What type of Portland cement should be used in a massive concrete placement such as a gravity dam (Low heat hydration)?

A

Type IV (Design and Control of Concrete Mixtures Page 110)

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4
Q

What type of Portland Cement should be used in a concrete mix when the forms must be removed early?

A

Type III (Design and Control of Concrete Mixtures Page 110)

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5
Q

What is the effect of algae in mixing water used for concrete?

A

Reduced strength (Design and Control of Concrete Mixtures Page 179)

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6
Q

What type of concrete joint is used for both horizontal and vertical movement at adjoining concrete surfaces?

A

Isolation joint (Design and Control of Concrete Mixtures Page 437)

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7
Q

What is the effect of high heat in concrete?

A

Reduced slump (Design and Control of Concrete Mixtures Page 467)

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8
Q

The abrasion resistance of concrete is dependent upon:

A

Adequate curing (Design and Control of Concrete Mixtures Page 542)

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9
Q

What is the minimum density for lightweight insulating concrete in pounds per cubic foot?

A

15 (Design and Control of Concrete Mixtures Page 554)

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10
Q

Concrete cover is the minimum distance from the:

A

Outside of the reinforcing bar to face of concrete (Design and Control of Concrete Mixtures – Older Edition )

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11
Q

What is the finish calculation for figuring the cubic yards of concrete if the beginning calculation is Length x?

A

Width x Depth (in feet) divided by 27 (Design and Control of Concrete Mixtures Calculation)

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12
Q

What type of concrete has a low heat of hydration?

A

Type IV (Design and Control of Concrete Mixtures Page 110)

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13
Q

What type of concrete has a moderate sulfate resistance?

A

Type II (Design and Control of Concrete Mixtures Page 110)

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14
Q

What is the maximum slump for lightweight concrete?

A

5 inches (Design and Control of Concrete Mixtures Page 553)

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15
Q

Why should you use a chute for placing concrete instead of dropping it in place?

A

Helps concrete to not separate without segregation (Design and Control of Concrete Mixtures Page 404)

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16
Q

Which admixture is added in concrete to accelerate the rate of hydration and increase strength development at an early age?

A

Accelerating admixture (Design and Control of Concrete Mixtures Page 222)

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17
Q

On concrete thickness up to about seven inches, which of the below are true about air content to slump?

A

Air content increases as slump increases (Design and Control of Concrete Mixtures Page 269)

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18
Q

Which of the below would increase the abrasive strength of concrete?

A

Low water-cement ratio, Steel - troweled surface, Harder aggregate (Design and Control of Concrete Mixtures Page 283)

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19
Q

What is the purpose of using vibrators when doing concrete work?

A

Get rid of air voids, Consolidates the concrete (Design and Control of Concrete Mixtures Page 423)

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20
Q

Tools used for finishing air-entrained concrete should be constructed from which of the below?

A

Aluminum or magnesium (Design and Control of Concrete Mixtures Page 429)

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21
Q

Normal weight and lightweight concrete exposed to freezing and thawing or deicing chemicals shall be:

A

Air entrained (Design and Control of Concrete Mixtures Page 359)

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22
Q

Hotter than normal temperatures when pouring concrete has what consequences (or “What is true” about pouring concrete in hot weather?)

A

Increased slump loss, Increased tendency for cracking, Long term strength loss (Design and Control of Concrete Mixtures Page 467)

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23
Q

Freezing temperatures have what effect (or it may have asked what is true) on fresh concrete

A

Concrete that has been frozen will not be as impermeable as concrete that wasn’t frozen (Design and Control of Concrete Mixtures Page 482)

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24
Q

Once water is added to a concrete mix at the mixing plant, what is the maximum time for delivery and discharge from truck?

A

1 ½ hours (Design and Control of Concrete Mixtures Page 400)

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25
What is true about moisture in concrete?
It is important to prevent moisture from leaving the concrete, Excessive moisture loss will result in concrete cracking. both 1 and 3 (Design and Control of Concrete Mixtures Page 452)
26
When pumping concrete into tightly reinforced forms which of the below should be used?
Superplasticizers (Design and Control of Concrete Mixtures Page 217)
27
Concrete that is exposed to salt water, what is the correct mixture added to protect rebar?
Corrosion resistant mixture (Design and Control of Concrete Mixtures Page 225)
28
Low slump means that the concrete is;
Stiff (Design and Control of Concrete Mixtures Page 362)
29
Which of the following is not a method to control plastic shrinkage?
Use of a richer mix design (Design and Control of Concrete Mixtures Page 452 and 453)
30
What type of concrete is high early strength concrete?
III (Design and Control of Concrete Mixtures Page 110)
31
All of the following are methods of curing concrete except:
Using plastic forms (Design and Control of Concrete Mixtures Pages 452 thru 458 )
32
For the strength of concrete to continue to increase with time, the relative humidity within the concrete should remain above:
80% (Design and Control of Concrete Mixtures Page 274)
33
Which of the following factors does not influence workability of concrete?
Calcium chloride (Design and Control of Concrete Mixtures Page 222)
34
Durability of concrete can be related directly to:
Compressive strength (Design and Control of Concrete Mixtures Page 311)
35
What is the most effective method for controlling shrinkage cracking in concrete?
Providing joints (contraction joints) (Design and Control of Concrete Mixtures Page 282)
36
The resistance of hardened concrete to freezing and thawing is significantly improved by adding:
Air entrainment (Design and Control of Concrete Mixtures Page 263)
37
What is the effect of vibratory action on a concrete mixture?
all; It permits the use of a stiffer mixture, It causes the mix to be more liquid, Removes trapped air (Design and Control of Concrete Mixtures Page 272)
38
What is the effective period of time for increased workability that can be expected when placing concrete using super plasticizer?
30 to 60 minutes (Design and Control of Concrete Mixtures Page 219)
39
What is most closely related to abrasive strength of concrete?
Compressive strength (Design and Control of Concrete Mixtures Page 283)
40
How do higher temperatures at time of placement affect concrete?
Concrete has a lower slump (Design and Control of Concrete Mixtures Page 467) The lower the slump, the stiffer the concrete and makes it hard to place correctly.
41
Besides the water to cement ratio, what else determines the final compressive strength of concrete?
Age (Design and Control of Concrete Mixtures Page 274)
42
The most common plasticizer used in concrete is:
Lime (Design and Control of Concrete Mixtures Page 219)
43
For the most part you do not need to add anything to the concrete mix other than the standard ingredients, but on occasion additives do help to make the job easier. Which of the below is not considered an additive?
Water (Design and Control of Concrete Mixtures Page 212 thru 221)
44
What is the minimum 28-day compressive strength for lightweight aggregate concrete?
2500 psi (Design and Control of Concrete Mixtures Page 551)
45
The concrete arrives on a construction project stiffer that needed and the workers add water to the mix. How will this affect the mix?
Makes the mix weaker, Increases the water to cement ratio (Design and Control of Concrete Mixtures Page 357)
46
What is the purpose for vibrating concrete?
To remove trapped air, To consolidate the concrete, (Design and Control of Concrete Mixtures Page 423)
47
What is the time and revolutions of the drum when truck concrete mixers are used, the time between batching and complete discharge after water has been added to the cement and aggregates?
1 ½ hours, 300 times (Design and Control of Concrete Mixtures Page 400)
48
When mixing concrete, the reason for adding water to the cement is called:
Hydration (Design and Control of Concrete Mixtures Page 451)
49
What temperature range would be considered a hot weather condition for concrete?
77 degrees to 90 degrees (Design and Control of Concrete Mixtures Page 466 Note: 2016 Edition is 75 to 100 degrees)
50
What is the definition of pre-cast concrete?
Concrete that is cast and poured off site and transported to its final position (Design and Control of Concrete Mixtures Page 576 Definitions)
51
What is the best temperature for curing concrete?
50 to 70 degrees (Design and Control of Concrete Mixtures Page 461)
52
What is the main reason for taking a slump test?
Check the workability and consistency of the concrete (Design and Control of Concrete Mixtures Page 362)
53
When pouring concrete in hot weather, this is a condition that can occur:
Shrinkage cracks, Loss of strength, Fast hydration (stiff very quickly) (Design and Control of Concrete Mixtures Page 467)
54
To resist the deterioration of concrete due to deicers, freezing and thawing, which of the following admixtures need to be added?
Air-entrainment (Design and Control of Concrete Mixtures Page 485)
55
What is the purpose for vibrating concrete?
Separate the course aggregate (Design and Control of Concrete Mixtures Page 272)
56
What admixture needs to be added to concrete in hot weather conditions?
Retardant (Design and Control of Concrete Mixtures Page 221)
57
Definition of Type II concrete.
Moderate / Low sulfate resistance (Design and Control of Concrete Mixtures Page 110)
58
Definition of Type III Concrete.
High early strength – early set (Design and Control of Concrete Mixtures Page 110)
59
Definition of Type IV concrete.
Low heat of hydration (Design and Control of Concrete Mixtures Page 110)
60
Which of the below is true about the volume of concrete once it sets up?
Stays about the same (changes slightly) (Design and Control of Concrete Mixtures Page 287)
61
What are the proportions of concrete made up of?
Sand, cement, water and course aggregate (Design and Control of Concrete Mixtures Page 1)
62
What effect does low slump have on concrete?
More stiff, hard to work (Design and Control of Concrete Mixtures Page 362 Low slump is stiff, high slump is watery)
63
What is the definition of air-entrained concrete?
Concrete that will have resistance to freeze – thaw conditions when exposed to water and de-icing conditions (Design and Control of Concrete Mixtures Page 359)
64
What is the definition of superplasticizers?
High range water reducers that are added to concrete with a low-to-normal slump and water ratio to make high slump concrete. (Design and Control of Concrete Mixtures Page 217)
65
What is the definition of slump?
It is a test for the rigidity (consistency) of uncured concrete. (Design and Control of Concrete Mixtures Definitions and Page 577 Low slump means that the concrete is stiff while high slump means the concrete is watery, easier to use and work with.)
66
What is a characteristic of pouring concrete at low (cold) temperatures?
Concrete gains very little strength at low temperatures (Design and Control of Concrete Mixtures Page 481)
67
What is a common admixture to add to concrete to help hydration and strength when pouring in cold weather?
Accelerating admixture (Design and Control of Concrete Mixtures Page 222)
68
What is the average size of course aggregates (rock/gravel) in concrete?
3/4 inch (Design and Control of Concrete Mixtures Page 181)
69
How many days does it take for concrete to reach its minimum design compressive strength?
28 days (Design and Control of Concrete Mixtures Page 277)
70
When using air-entrainment in concrete as an admixture it will help with the freezing and thawing conditions over the life of the concrete, air-entrainment also will:
Improve the workability (Design and Control of Concrete Mixtures Page 359)
71
Abrasion resistance is closely related to the:
Compressive strength of concrete. (Design and Control of Concrete Mixtures Page 283)
72
Insulating concrete is a light weight concrete with the aggregate of:
Perlite (Design and Control of Concrete Mixtures Page 554)
73
What is the definition of low permeability of concrete?
Low permeability will produce acid and corrosion resistance of concrete (Design and Control of Concrete Mixtures Page 279)
74
What is the definition of high permeability of concrete?
High permeability of concrete will cause reinforcing to corrode. (Design and Control of Concrete Mixtures Page 542)
75
What is the most preferred method to consolidate concrete?
Mechanical vibrators (Design and Control of Concrete Mixtures Page 272)
76
What type of admixture is high early concrete?
Accelerating admixture (Design and Control of Concrete Mixtures Page 222)
77
When pouring concrete with reinforcement that will be exposed to seawater, what type of admixture should be used?
Corrosion inhibitors (Design and Control of Concrete Mixtures Page 225)
78
For lightweight concrete with an overdry density of 50 pcf (pounds per cubic feet) which of below is correct?
Maximum slump of 5 inches (Design and Control of Concrete Mixtures Page 553)
79
Type II concrete is used for what kind of construction?
Moderate sulfate resistance (Design and Control of Concrete Mixtures Page 110)
80
Which of the below statements is true about moisture when curing concrete?
It is important to prevent the loss of moisture from concrete during curing (Design and Control of Concrete Mixtures Page 451)
81
What should be applied to hardened concrete to protect from deicing chemicals?
Air entrainment (Design and Control of Concrete Mixtures Page 359)
82
What additive is used for concrete at high temperature or too hot?
Retardant (Design and Control of Concrete Mixtures Page 221)
83
What is true about how to finish light weight concrete?
Need to start finishing earlier than normal concrete (Design and Control of Concrete Mixtures Page 553)
84
Which of the below would be an admixture in concrete?
Air-Entrainment (Design and Control of Concrete Mixtures Page 212)
85
What is the range of air entrainment of light weight moderate exposure structural concrete?
5 to 8% (Design and Control of Concrete Mixtures Page 552)
86
What is the best slump used for light weight concrete?
2 to 4 inches (Design and Control of Concrete Mixtures Page 553)
87
What is the definition of Type V concrete?
High sulfate resistance (Design and Control of Concrete Mixtures Page 110)
88
What is the optimum finishing slump for light weight concrete?
none of the above (Design and Control of Concrete Mixtures Page 553 The best slump is 2 to 4 inches.)
89
What is the slump used for lightweight concrete that can be placed under conditions that would normally require a slump of 3 to 5 inches for normal-weight concrete?
2 to 3 inches (Design and Control of Concrete Mixtures Page 553)
90
Which of the below would more likely require using a vibrator to consolidate concrete?
Mixture with aggregate (Design and Control of Concrete Mixture Page 272)
91
Which type of concrete would be resistant to attack by increased acid (farmyard) wastes?
Low permeability (Design and Control of Concrete Mixture 14th Edition Page 542)
92
What is the best type of joint to control cracking in a driveway?
Contraction (Design and Control of Concrete Mixture Page 282)
93
What is the most widely used supplementary cementitious material in concrete?
Fly ash (Design and Control of Concrete Mixture Page 148 )
94
What is the best type of concrete mix to use in a drain structure that requires moderate sulfate concrete?
II (Design and Control of Concrete Mixtures Page 110)
95
Which group of concrete uses expanded aggregates such as perlite?
I (Design and Control of Concrete Mixtures Page 554)
96
What is the best method for curing concrete?
Moist condition for 7 days at 50 degrees (Design and Control of Concrete Mixtures Page 453 and 460 Note: ACI 318 Code is 7 days and 50 Degrees and 2016 Edition is 7 days at 40 degrees)
97
What is the proper method for vibrating concrete?
Insert vibrator quickly and remove when large air bubbles stop surfacing (Design and Control of Concrete Mixtures Page 425)
98
What is the most effective way to prevent water evaporation when curing concrete?
Fogging (Design and Control of Concrete Mixtures Page 453)
99
What is the relationship between concrete strength and hard aggregate?
Hard aggregate is more wear resistant (Design and Control of Concrete Mixtures Page 283)
100
What admixture in needed when placing concrete in areas of closely spaced and congested reinforcing steel to improve concrete flow without weakening the concrete mix?
Superplasticizer (Design and Control of Concrete Mixtures Page 217)
101
How much pcf of perlite is used in Group I lightweight concrete?
15 and 50 pcf (Design and Control of Concrete Mixtures 14th Edition Page 554)
102
Which of the below would prevent surface scaling of concrete?
Air entrainment (Design and Control of Concrete Mixtures Page 165)
103
What is the minimum depth of contraction joints in concrete?
25% of slab (1/4 of slab) (Design and Control of Concrete Mixtures Page 437)
104
What of the below is not a characteristic of a slab on grade?
Grass and sod underneath (Design and Control of Concrete Mixtures Page 412)
105
What can be added to Group I light weight concrete that has 15 pcf of perlite?
Additional perlite (Design and Control of Concrete Mixtures Page 554)
106
Which of the following is not considered an aggregate in concrete and should be avoided?
Chert (Design and Control of Concrete Mixtures Page 181)
107
What is the minimum to maximum water to cement ratio for a concrete mix?
.40 to .50 (Design and Control of Concrete Mixtures Tables 15-1 Page 356 Note: 16th Edition shows .40 minimum to .55 maximum)
107
What is the required temperature range for test cylinders to be stored in the field?
60 to 80 degrees F (Design and Control of Concrete Mixtures Page 489)
108
What is the percent of the tensile strength of unreinforced concrete in relationship to the compressive strength of unreinforced concrete?
10 percent (Design and Control of Concrete Mixtures Page 249)
109
What is the maximum spacing for expansion joints in sidewalks?
30 feet (Design and Control of Concrete Mixtures 14th Edition Page 437)
110
Which of the below is true about a contraction joint in a concrete wall?
It is a plane of weakness in the wall (Design and Control of Concrete Mixtures Page 438)
111
What material is placed on a concrete slab on grade between the concrete and the sub grade?
Vapor retarder (Design and Control of Concrete Mixtures Page 413)

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