Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Carpentry > G7 > Flashcards

G7 Flashcards

1
Q

When is a conveyor used to transport concrete

A

When transporting concrete from an on site batch plant to the point of placement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How soon after the mix water is added to the concrete mixture must the concrete be placed

A

120 mins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Explain tailgate delivery

A

When the concrete is delivered directly to the form work

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

When is a concrete bucket used to place concrete

A

When moving concrete with a crane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are two basic types of concrete pumps

A

Line pump

Crane mounted pump

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How should concrete be placed on a sloped surface

A

Starting at the bottom of the slope and proceeding upwards

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the maximum spacing of vibrator insertion points when vibrating a wall

A

1 1/2 times radius of influence…if unknown - 600mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How can you tell when consolidation is adequate

A

When air bubbles stop rising

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

When are external vibrators used

A

When steel forms are used

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

At what stages of finishing is an edger used and why

A

After floating, troweling and broom finish to move aggregate away from the edge of the forms and for decorative purposes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the purpose of hand floating/bull floating

A

Pushes aggregate below the surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why is a divider tool not used to make control joints

A

Does not cut deep enough

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

When is the placing of concrete complete

A

When concrete has been placed up to the screed level

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Why should bleed water be allowed to evaporate

A

Because it is not needed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Explain how a broom finish is created

A

With a smooth stiff bristle broom

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

When are screeds removed from the concrete

A

After strike off

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the purpose of a screed

A

Concrete placement guide and guide for strike off bar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How is the top of a concrete wall finished

A

Float finish

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the purpose of knee boards

A

Supports workers weight properly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What tool is used to transfer flexible patterns

A

Tamping/stamping tool

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the two required conditions for proper concrete curing

A

Temperature and hydration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is considered a favourable air temperature for concrete curing

A

15 - 20 degrees C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Explain the hydration process

A

Chemical reaction that takes place when the water reacts with the cement

24
Q

4 methods of curing concrete

A
  • Water curing
  • Water retaining
  • Mechanical barriers (plastic, paper)
  • Chemical membranes
25
Q

How are chemical hardeners used

A

Sprayed/rolled onto the surface

26
Q

Why are some curing compounds coloured

A

So full coverage can be seen

27
Q

If two coats of curing compound are used, how is the second one applied

A

At right angles to the first application

28
Q

Minimum curing time required to allow the concrete to gain 70% of its 28-day strength

A

3 days (70%)

Not cured (50%)

7 days (90%)

Kept moist continually (will continue to gain strength indefinitely)

29
Q

Two purposes of chemical sealants

A

Durable and waterproof finish

30
Q

How are powdered hardeners applied to concrete

A

Sprinkled onto the surface

31
Q

Why should additional water not be added to the concrete when placing concrete in hot weather

A

Weakens concrete - increases the water cement ratio

Evaporation rates are extreme in it weather

32
Q

How is concrete cooled in hot weather

A

Cool aggregate by spraying with water

Cool mix with refrigeration

33
Q

Minimum temperature for curing concrete

A

10 degrees Celsius

34
Q

What pre cautions should be taken when using hot water in the concrete mixture

A

It will set very fast (flash set)

35
Q

What is the effect on concrete when using fossil-fuel- burning heaters un-ventilated enclosures

A

Carbon monoxide - can cause the concrete surface to become weak and dusty

36
Q

How long should form work be left in place during cold weather

A

Once compressive strength reaches 3.5MPa

37
Q

Four problems that can cause the form work to fail

A

Improper stripping and form removal

Inadequate bracing

Improper vibration

Unstable soil under mudsills

Shoring not plumb

38
Q

What can cause a concrete slab on grade to sag and crack

A

Settling, and or, heaving

Improper fill material

39
Q

What causes spalling

A

Premature removal of forms (around rustication strips and windows bucks especially)

40
Q

How can spalling be prevented

A

Using quality concrete that is placed and finished correctly

41
Q

What is a white crystalline growth on the surface of concrete called

A

Efflorescence

42
Q

Describe the procedure used to place concrete around bucks in a wall form

A

Vibrating well around bucks and or drilling holes to allow air to escape

43
Q

What causes efflorescence

A

Crystals of dissolved salts that were in the water used to make the concrete

44
Q

What is the maximum aggregate size that should be used when repairing concrete

A

Half depth of the patch

45
Q

What are the advantages of using pre mixed grout

A

Can be mixed to liquid consistency and still provide strength

46
Q

Why must you wet the area to be patched

A

To ensure the old concrete doesn’t absorb water from the latching material

47
Q

What surface repairs situation require using forms

A

Concrete patches

48
Q

What is the minimum slump of repair concrete

A

50mm

49
Q

How long should a patched area be allowed to cure

A

3 days

50
Q

Why are metallic aggregates used in some grout

A

Offsets shrinkage if cementious materials

51
Q

Why would non metallic grouts be used

A

Does not use iron compounds and does not rust the concrete

52
Q

How are liquid grouts used

A

For small gaps - mixed thin enough to be pumped or poured - requires formwork

53
Q

What are the disadvantages of using liquid grouts

A

Small gaps in the form work need to be caulked to keep the grout from escaping

54
Q

What is cementation

A

The use of liquid grout

55
Q

What safety precautions must be taken with concrete treatments

A

Some of the chemicals used are dangerous - always refer to the MSDS

56
Q

What are the environmental concerns associated with concrete treatments

A

Can be hard on the ecology of a stream or the ground water

57
Q

How is a suspended concrete slab water proofed

A

Torch on

Carpentry (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions