Bu basic CH6 Flashcards
1
Q
- What is a synthetic construction material made by mixing cement, fine aggregate, coarse aggregate, and water in the proper proportions? (Page 6-4)
A
concrete
2
Q
- What property of concrete refers to the extent to which the material is capable of resisting deterioration from exposure to service conditions? (Page 6-5)
A
durability
3
Q
- What is a mixture of only cement and water called? (Page 6-8)
A
cement paste
4
Q
- What is the type of cement most used today? (Page 6-8)
A
portland cement
5
Q
- How many types of Portland cement covered under Standard Specifications for Portland Cement? (Page 6-8)
A
five
6
Q
- What type of cement is intended for concrete that is not subjected to sulfate attack or damage by the heat of hydration? (Page 6-8)
A
type 1
7
Q
- Type 1 cement reaches its design strength in about how many days? (Page 6-8)
A
28 days
8
Q
- How many days odes it take for Type II cement to reach its design strength? (Page 6-8)
A
45 days
9
Q
- Type III cement is high early strength cement that produces design strengths at an early age, usually in how many days or less? (Page 6-9)
A
7 days
10
Q
- Type IV cement reaches its design strength in about how many days? (Page 6-9)
A
90 days
11
Q
- What type of cement should be used where concrete is subjected to severe sulfate action? (Page 6-9)
A
type V
12
Q
- How many days does it take Type V cement to reach its design strength? (Page 6-9)
A
60 days
13
Q
- What is the material combined with cement and water to make concrete called? (Page 6-9)
A
aggregate
14
Q
- What percentage of concrete volume does aggregate make up? (Page 6-9)
A
60 to 80
15
Q
- For most building concrete, coarse aggregate consists of gravel or crushed stone up to what in size? (Page 6-9)
A
1.5 inches
16
Q
- Aggregates larger than what are all coarse? (Page 6-10)
A
no. 4
17
Q
- What refers to particles of the same size tending to gather together when the material is loaded, transported, or otherwise disturbed? (Page 6-13)
A
segregation
18
Q
- Tests show that the compressive strength of concrete made with seawater is what percent less than that obtained using fresh water? (Page 6-14)
A
10 to 30
19
Q
- What speed up the settling and hardening of concrete? (Page 6-15)
A
accelerating admixtures
20
Q
- What are often used in warm weather to keep the concrete from setting before it can be placed and finished? (Page 6-15)
A
retarders
21
Q
- Portland cement is packed in cloth or paper sacks, each weighing how many pounds? (Page 6-15)
A
94
22
Q
- What is a means of measuring the consistency of concrete using a slump cone? (Page 6-19)
A
slump testing
23
Q
- Compression tests of concrete cylinders are specified in what? (Page 6-23)
A
astm c 39
24
Q
- What refers to a water-sand-cement mixture used to plug holes or cracks in concrete, seal joints, fill spaces between machinery bedplates and concrete foundations, and for similar plugging or sealing purposes? (Page 6-25)
A
grout
25
Q
- A batch of concrete that is to be hand mixed by a couple of crewmembers should not be much larger than what? (Page 6-27)
A
1 cubic yard
26
Q
- Rate of capacities of concrete mixers range from as small as 2 cubic feet to as large as what? (Page 6- 28)
A
7 cubic yards
27
Q
- The time elapsing between the introduction of the mixing water to the cement and aggregates and the placing of the concrete in the forms should not exceed how long? (Page 6-29)
A
1.5 hours
28
Q
- The time elapsing between the introduction of the mixing water to the cement and aggregates and the placing of the concrete in the forms should not exceed how long? (Page 6-29)
A
transit mixing
29
Q
- Forms are generally constructed from earth, metal, wood, fiber, or what else? (Page 6-32)
A
fabric
30
Q
- Forms are generally constructed from earth, metal, wood, fiber, or what else? (Page 6-32)
A
wooden
31
Q
- Plywood is made in widths up to how many inches? (Page 6-33)
A
48inches
32
Q
- What types of forms are ideal for round concrete columns and other applications where performed shapes are feasible since they require no form fabrication at the job site? (Page 6-33)
A
fiber
33
Q
- What forms the surfaces of the concrete? (Page 6-39)
A
construction sheathing
34
Q
- On plywood, what works better than oil in preventing moisture from raising the grain and detracting from the finished concrete surface? (Page 6-48)
A
shellac
35
Q
- What is the combination known as when steel is embedded in concrete in a manner that assists it in carrying imposed loads? (Page 6-51)
A
reinforced concrete
36
Q
- Specifications and designs are usually used when wire fabric is being lapped. As a rule of thumb, one complete lap is usually sufficient with a minimum of how many inches between laps? (Page 6-51)
A
2
37
Q
- Footings and other principal structural members that are against the ground should have at least how many inches of concrete between steel and ground? (Page 6-54)
A
3 inches
38
Q
- If the concrete surface is to be in contact with the ground or exposed to the weather after removal of the forms, the protective covering of concrete over the steel should be 2 inches for bars larger than No. 5 and how many inches for bars No. 5 or smaller? (Page 6-54)
A
1.5 inches
39
Q
- Because rebar is available only in certain lengths, it must be spliced together for longer runs. Where splices are not dimensioned on the drawings, lap the bars not less than 30 times the diameter, or not less than how many inches, whichever is more? (Page 6-57)
A
12
40
Q
- Stresses in concrete can be controlled by the proper placement of what in the structure? (Page 6-57)
A
joints
41
Q
- What type of joints are used to separate adjacent structural members? (Page 6-57)
A
isolation
42
Q
- Drives and walks wider than how many feet should have a longitudinal joint down the center? (Page 6-
A
10 to 12
43
Q
- In patio slabs, joints should not be more than how many feet apart in both directions? (Page 6-59)
A
10
44
Q
- What is used to cut longitudinal and transverse joints in finished concrete pavements? (Page 6-61)
A
concrete saw
45
Q
- Unless the free fall into the form is less than how many feet, use vertical pipes, suitable drop chutes, or baffles when dropping the concrete from the delivery chute? (Page 6-62)
A
4 feet
46
Q
- To avoid excessive pressure on large project forms, the filling rate should not exceed how many vertical feet per hour? (Page 6-63)
A
4
47
Q
What allow placement of mixtures that are too stiff to place any other way? (Page 6-65)
A
vibrators
48
Q
- When using an internal vibrator, insert it at approximately 18-inch intervals into air-entrained concrete for 5 to 10 seconds and into nonair-entrained concrete for how many seconds? (Page 6-65)
A
10-15
49
Q
- Concrete shouldn’t be vibrated that has a slump of how many or more inches? (Page 6-66)
A
5 inches
50
Q
- Low-frequency vibrating speeds of how many vibrations per minute should be used when surface vibrating slabs up to 6 inches thick? (Page 6-66)
A
3000-6000
51
Q
- Do not leave a vibrator in the concrete too long in concrete mixes which have a slump of more than how many inches as it will cause segregation? (Page 6-66)
A
3 inches
52
Q
- The top surface of a floor slab, sidewalk, or pavement is rarely placed at the exact specified elevation. What brings the surface to the required elevation by striking off the excess concrete? (Page 6-67)
A
screeding
53
Q
- What tool does hand screeding require? (Page 6-67)
A
straightedge
54
Q
- Surfaces up to 30 feet wide can be hand screeded, but the efficiency of this method diminishes on surfaces more than how many feet wide? (Page 6-67)
A
10
55
Q
- Concrete is usually paced how many feet ahead of the mechanical screed and shoveled as close as possible to its final resting place? (Page 6-69)
A
15-20
56
Q
- What is used to compact the concrete into a dense mass and to force the larger particles of coarse aggregate slightly below the surface? (Page 6-70)
A
hand tamping
57
Q
- What is the period of time from consolidation to the point where the concrete reaches its design strength called? (Page 6-74)
A
curing
58
Q
- For most structural use, what is the curing period for cast-in-place concrete? (Page 6-75)
A
3 days to 2 weeks
59
Q
- Haunch boards and wall forms can usually be removed after how long? (Page 6-77)
A
1 day
60
Q
- How many days to column forms usually require before they can be removed? (Page 6-77)
A
3
61
Q
- Removal of forms for soffits on girders and beams can usually be done after how many days? (Page 6- 77)
A
7
62
Q
- Specifications dictate that forms can usually be removed after a gain of what percent of 28 day strength requirement? (Page 6-77)
A
70%
63
Q
- When building casting surfaces the slab should be at least how many inches thick? (Page 6-83)
A
6
64
Q
- Bond breaking types are broken into what two general types? (Page 6-84)
A
sheet materials and liquids