Nb Block 3 Concrete

Front 1

Concrete is a mixture of these 3 materials

Back 1

Aggregate

Cement

Water

Front 2

How does excess water in a concrete mixture effect the strength of concrete?

Back 2

The strength will be reduced

Front 3

Strips of pliable material placed between slabs and other structures.

Back 3

Expansion joints

Front 4

Term used for grooves cut into a concrete slab to prevent cracking

Back 4

Control joint

Front 5

How thick should control joints be cut?

Back 5

Cut to a depth 25% of the thickness of the slab

Front 6

What does proper curing do to concrete?

Back 6

Slows heat loss.

Prevents concrete from drying too quickly

Front 7

Type of finish

Back 7

Exposed aggregate

Front 8

Back 8

Concrete spreader

Front 9

Back 9

Darby

Front 10

Back 10

Hand float

Front 11

Back 11

Concrete edger

Front 12

Back 12

Concrete trowel

Front 13

Back 13

Fresno

Front 14

Back 14

Bull float

Front 15

Back 15

Vibration screed

Front 16

Type of concrete that contains air bubbles that are distributed throughout the cement paste.

Back 16

Air entrained concrete

Front 17

Why do we air-entrain concrete?

Back 17

To improve the durability of concrete exposed to moisture during cycles of freezing and thawing

Front 18

Water that rises to the surface of freshly placed concrete.

Back 18

Bleed water

Front 19

The way to measure concrete consistency

Back 19

Slump test

Front 20

What is this issue called?

What causes it?

Back 20

Crusting

Occurs when the surface of freshly placed concrete dries too quickly

Front 21

The action taken to maintain favorable moisture and temperature conditions of freshly placed concrete.

Back 21

Curing

Front 22

Purpose of a curing compound

Back 22

Forms a membrane on the concrete to slow evaporation

Front 23

A method for dealing or repairing cracks In concrete by low pressure injection

Back 23

Epoxy injection

Front 24

Flyash

Back 24

A byproduct resulting from the combustion of powdered coal.

Sometimes used as a cement replacement in concrete

Front 25

Why shouldn't a fresno be used on air entrained exterior concrete?

Back 25

It seals over the top of the slab, trapping bleed water below the surface

Front 26

Concrete in which metal is embedded so that the two materials act together in resisting forces

Back 26

Reinforced Concrete

Front 27

What are the measurements for the mould used in a slump test?

Back 27

Front 28

How many equal layers of concrete should be used in the mould during a slump test?

Back 28

4 equal layers

Front 29

Type of slump test result

Back 29

True slump

Front 30

Type of slump test result

Back 30

Zero slump.

Indication of a low water-cement ratio.

Front 31

Type of slump test result

Back 31

Collapsed.

Indication of a high water-cement ratio

Front 32

What is a typical concrete mix?

Back 32

10-15% cement

60-75% aggregate

15-20% water

Front 33

High quality concrete is produced by lowering the ______ as much as possible without sacrificing the workability of the wet concrete.

Back 33

Water-cement ratio

Front 34

The process in which cement and water harden and bind the aggregates into a solid mass.

Back 34

Hydration

Front 35

How long does a concrete surface have to be kept moist to permit the hydration process?

Back 35

5 to 7 days after concrete placement

Front 36

What happens to concrete in hot temperatures?

Back 36

Too much water is lost during evaporation

Front 37

What happens to concrete if the temperature gets close to freezing?

Back 37

Hydration slows to nearly a standstill

Front 38

The amount of entrained air is usually between _% and_% of the volume of concrete.

Back 38

4% -7%

Front 39

Which type of Portland cement do we most often use in our industry?

Back 39

Type 1.

Type 1A (air entrained)

General purpose cement