Ch. 36 - Concrete Flashcards Preview

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Flashcards in Ch. 36 - Concrete Deck (56)
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1
Q

Concrete was first discovered by the ______.

A

Romans

2
Q

What engineer used reinforced concrete early on in many innovative structures? He is famous for the Exhibition building in Turin and the Sports Palace in Rome.

A

Pier Luigi Nervi

3
Q

What is the most common material for formwork to be made from?

A

Plywood

4
Q

What is a slip form?

A

A form that moves as concrete cures. It is used for tunnels and high rise building cores.

5
Q

What are flying forms?

A

Large fabricated forms that can be removed after the concrete has cured and then reused for an identical section above. These are used for hotels, apartments or other highly repetitive structures.

6
Q

What is the maximum tolerance variation in plumb for columns, piers, and walls?

A

1/4” per 10ft of length

7
Q

What are the two types of reinforcing steel used for cast-in-place concrete?

A

Deformed bars and welded wire fabric

8
Q

How is rebar designated (in size/name)?

A

1/8” increments in the nominal diameter.

Ex. No. 6 Bar is 6/8” or 3/4”.

9
Q

What does the grade of a rebar represent? (such as grade 60)

A

Yield strength in kips per square inch.

10
Q

Name the five types of cement.

A
I - Standard Cement
II - Modified Cement
III - High-Early-Strength Cement
IV - Low-Heat Cement
V - Sulfate Resisting Cement
11
Q

What are admixtures?

A

Chemicals or other materials added to concrete to impart certain qualities such as speed hydration, hardening, and workability.

12
Q

What is the advantage to Self- Consolidating concrete?

A

It can be placed by using only its weight without the use of vibration to compact it, increasing productivity.

13
Q

What is a slump test?

A

Measures the consistency of concrete by placing concrete in a cone, removing the cone, and measuring the distance the concrete slumps.

14
Q

What causes laitance?

A

Too much water in concrete

15
Q

Name two tests used on concrete (besides the slump test).

A

Cylinder Test; Core Cylinder Test; Kelly Ball Test; Impact Hammer Test; K-Slump Test

16
Q

What is the maximum distance concrete should be dropped when pouring?

A

5 feet

17
Q

What is a control joint for?

A

controlling the normal stress cracking that occurs due to temperature fluctuation instead of allowing it to happen at random.

18
Q

Where do construction joints occur?

A

Wherever two successive pours of concrete.

19
Q

What do expansion joints allow for?

A

Movement of entire sections of structure independently of one another.

20
Q

Where can isolation joints be used?

A

Between two adjacent sections such as separating columns from slabs and slabs from foundations.

21
Q

A mineral that expands upon being heated, used in the expanded state for heat/sound insulation and fireproofing.

A

Vermiculite

22
Q

Form of obsidian formed by cracking of cooling volcanic glass, used as insulation.

A

Perlite

23
Q

For columns, piers, and walls what is the maximum variation in plumb?

A

1/4” per 10’

24
Q

What is the maximum variation out of plumb for the total height of the structure for INTERIOR columns?

A

1”

25
Q

What is the maximum variation out of plumb for the total height of the structure for EXTERIOR columns?

A

1/2”

26
Q

How many weeks should concrete ideally be allowed to cure for before resilient flooring is allowed to be installed?

A

6 weeks

27
Q

what is the ideal water to cement ratio?

A

.45-.50 avg.

.35-.40 min.

28
Q

Fine aggregates are those that pass through a _______ seive?

A

number 4

29
Q

What are the aggregates in lightweight concrete?

A

Expanded clays, slags, and shales

30
Q

What are the aggregates in insulating concrete?

A

pumice, or cinders

31
Q

What are 6 different types of add mixtures that can be added to concrete?

A
Air entraining agents
Accelerators
Plasticizers
Retarders
Waterproofing
Fly Ash
32
Q

Why would fly ash be specified as an addmixture in concrete?

A

It is a sustainable material left over from the coal burning process that increases the strength, decreases permeability, reduces temperature rise, increases sulfate resistance, and improves work-ability. It can also decrease the amount of cement required.

33
Q

How thick is the carbon fiber grid, in carbon fiber concrete, and how much stronger is it than steel mesh?

A

0.04 in thick and 7 times stronger

34
Q

How much strength does concrete gain after its first week of curing?

A

70% of its strength

35
Q

How much strength can concrete lose when it freezes while curing?

A

50%

36
Q

How far can a typical 4’ wide, by 12” deep concrete core slab extend?

A

36’

37
Q

What is the architectural concrete finish called where shaped with liners of plastic wood or metal. Parallel rib liners are a common type. Joints and form tie holes are treated as desired either left exposed or patched.

A

Form Liner

38
Q

What is the architectural concrete finish called where the surface of the concrete is wetted and scrubbed with a wire or fiberbrush to remove some of the surface mortar and expose the coarse aggregate?

A

Scrubbed

39
Q

What is the architectural concrete finish called where the surface of the concrete is wetted with muriatic acid to expose and bring out the full color of the aggregate?

A

Acid Wash

40
Q

What is the architectural concrete finish called where a high pressure water jet mixed with air is used to remove some of the mortar and expose the aggregate

A

Water Jet

41
Q

What is the architectural concrete finish called where you have a rugged heavy texture by removing a portion of the surface made with form liners. The type of texture depends on the liner

A

Bush Hammering

42
Q

What is the architectural concrete finish called where finishes include the application of other materials such as stucco or concrete?

A

Applied

43
Q

What is the architectural concrete finish called that is produced by removing surface material from the concrete exposing the aggregate to varying degrees as specified by light medium or heavy.

A

Sand Blasted

44
Q

What is the architectural concrete finish called where the surface of the concrete is wetted and rubbed with a carborundum brick to produce a smooth uniform color and texture?

A

Smooth

45
Q

What is the architectural concrete finish called where grout is applied over the concrete and smoothed out to make the appearance uniform and conceal defects?

A

Grout cleaned

46
Q

How many days does it take for high early strength concrete to reach its 28 day strength?>

A

7-14 days

47
Q

What does the A represent in Type IA, Type IIA, Type IIIA cement?

A

Air Entraining

48
Q

What are the advantages for Air Entraining concrete?

A

Great for cold climates, and pavings, increases workability, and increases concretes resistance to freeze thaw cycles

49
Q

How do you size aggregate in concrete?

A

Aggregate should not be larger than 3/4 the size of the spacing of the rebar. or larger than 1/3 the depth of the slab

50
Q

What are the advantages of plasticizers?

A

Greater workability and they increase the strength of the concrete by reducing the concretes need for water.

51
Q

What is silica fume?

A

The byproduct of computer manufacturing it has EXTREMELY HIGH strength and low permeability

52
Q

What are the advantages of silica fume in concrete?

A

Increased compression strength
Increased modulus of elasticity
Increased durability
Increased permeability

53
Q

What is a pozzolan?

A

A varicose natural/artificial material with similar properties to cement

54
Q

What is a fibrous admixture?

A

glass or steel fibers that when added to concrete increase its flexural stress.

55
Q

T/F High water to cement ratios decrease the strength of concrete.

A

True

56
Q

In rebar what does the S or W mean?

A

S - Carbon steel

W - Low alloy steel