G7 - LT #1 Conc. Finishing

Question 1

What stages of finishing is an edger used and why?

Answer 1

1) After bull floating, pushes large aggregates AWAY from the surface
2) Rounds over

Question 2

What is the purpose of hand floating and bull floating?

Answer 2

Pushes large aggregates down & allows bleed water to escape.

Question 3

Is a divider tool deep enough for control joints?

Answer 3

No

Question 4

When is the placing of the concrete completed?

Answer 4

After floating process

Question 5

Why should bleed water be allowed to evaporate first?

Answer 5

1) Not to dilute the concrete
2) causes dusting and crazing if you do not

Question 6

How to broom finish?

Answer 6

Float, edge, trowel, broom and edge again

Question 7

When are screeds removed from the concrete?

Answer 7

After strike-off

Question 8

What is the purpose of a screed?

Answer 8

Elevated guide for strike off

Question 9

How is the top of a concrete wall finished?

Answer 9

Remove the cleats from formwork and then float

Question 10

What is the purpose of kneed boards?

Answer 10

Distributes weight evenly

Question 11

What tool is used to transfer flexible patterns?

Answer 11

Tamper

Question 12

5 precautions to consider when finishing a concrete slab with a power trowel?

Answer 12

1) Concrete is flat & level
2) Will bear the pressure
3) bleed water is evaporated
4) cover entire surface uniformly
5) allow concrete to harden between passes

Question 13

How is the movement of a power trowel controlled?

Answer 13

1) Increase RPM to engage blade rotation
2) Push down on handles to move right & lift up to move left

Question 14

What is a burnished surface?

Answer 14

Mirror-like finish, made by making many passes with a power trowel at high speeds and a steep angle.

Question 15

What are two different types of blades used with power trowels?

Answer 15

Float & Trowel

Question 16

What safety precautions must be taken with concrete treatments?

Answer 16

Read the SDS Safety Data Sheet

Question 17

What are the environmental concerns associated with concrete treatments?

Answer 17

Streams & groundwater

Question 18

Describe how sealers and hardeners also act as a curing compound.

Answer 18

Coat the surface to stop moisture.

Question 19

How is exposed aggregate wall surface created?

Answer 19

Uniform coat of retardant, painted on the forming material, don’t slide concrete surface of coated form & strip carefully

Question 20

What is the difference between dampproofing & waterproofing materials?

Answer 20

Moisture vs. hydrostatic pressure

Question 21

How is a suspended concrete slab waterproofed?

Answer 21

Membrane roofing

Question 22

The top of a concrete wall that is left exposed must be finished with:

Answer 22

A steel trowel

Question 23

How can chamfer on concrete be made?

Answer 23

Chamfer strip in formwork or an edging tool

Question 24

Should well-proportioned concrete have excessive bleed water?

Answer 24

No

Question 25

What is concrete flatwork?

Answer 25

A slab that is suspended or placed on grade. Also surfaces of concrete landing and treads in concrete stairs.

Question 26

When does the finishing process of concrete start?

Answer 26

After bleeding water evaporates & carpenter can put weight on it with knee boards

Question 27

Can you add water to a concrete mix to ease placement?

Answer 27

No

Question 28

Is rebar at the bottom of a form or on ground effective?

Answer 28

No

Question 29

What is the purpose of screeding?

Answer 29

Levels off the concrete to the elevation set by the screeds?

Question 30

When is floating done

Answer 30

After concrete has been placed & screeded to level

Question 31

How are larger areas floated?

Answer 31

Bull float for larger areas

Question 32

Can a power trowel be used if bleed water is still remaining?

Answer 32

A power trowel should not be used until the bleed water has evaporated

Question 33

How does crazing occur?

Answer 33

Floating during bleed water period,changing the w:c ratio, surface cures at a different rate, dusting also occurs

Question 34

A large flat steel trowel is used first, is placed flat or on a steep angle?

Answer 34

Flat

Question 35

The second finishing, a smaller trowel is used, is it placed flat or on a steep angle?

Answer 35

Steep angle, allowing more pressure

Question 36

On exterior concrete walks and driveways, what sort of finish is needed?

Answer 36

A broom trowel, to prevent slips

Question 37

When is a broom trowel done?

Answer 37

After a single steel trowel is done

Question 38

When is an edger used?

Answer 38

Before each troweling and as the last step of a broom finish

Question 39

When is a fresno used?

Answer 39

Used to flatten out the ridges left by the bull float

Question 40

For flexible stamps, what tool is necessary?

Answer 40

A tamping tool

Question 41

Power trowel can be used in addition to or as an alternative to

Answer 41

The bull float, Fresno & steel trowel

Question 42

With a power trowel, which 2 blades are common?

Answer 42

Floats and trowel blades

Question 43

A float blade on a power trowel does what?

Answer 43

Final leveling of the concrete surface. Blade typically 10", kept flat initially. Run at 1/2 to 3/4 speed.

Question 44

What is crossover floating?

Answer 44

The second pass on a power trowel, the blades are tilted slightly and the engine is run at 3/4 speed Allows finisher to reach areas that were hard to access when travelling the first direction and helps level the slab

Question 45

On a power trowel, what does a trowel blade do?

Answer 45

Similar to the blade of a hand trowel, typically 8" wide each pass increases the density of the slab surface, with enough passes the op. can burnish the surface to a mirror-like finish

Question 46

The handles on a power trowel work how?

Answer 46

Lifting handing moves to the left, lowering moves to the right

Question 47

What is a curing compound?

Answer 47

Membrane curing compound consists of chemicals and waxes that are sprayed, brushed, or rolled on. Protect from early drying, in hot windy weather.

Question 48

What is a sealer?

Answer 48

Sealers are chemicals that the seal of the surface of concrete, prevent formation of dust on a worn concrete surface.

Question 49

What is a chemical hardener?

Answer 49

Provide hard-wearing concrete surface and prevent dusting. Also, act as sealers.

Question 50

Metallic or aggregate hardeners?

Answer 50

Used in areas where very heavy wear is, dry the top of concrete as it is being finished. made from iron, steel, or hard mineral aggregates

Question 51

Describe exposing aggregates

Answer 51

Vertical forms can be treated with chemicals that prevent the cement paste from setting on the surface next to the. Exposing chemicals are sprayed on slabs to retard the setting of the cement paste

Question 52

What is a bond breaker?

Answer 52

These chemicals are used to break the bond between layers of concrete, such as those used to tilt-up construction where multiple layers of concrete are cast one on top of the other.

Question 53

What are bonding agents?

Answer 53

Epoxies and adhesives are used to create a good bond between fresh concrete placed over old concrete

Question 54

What is dampproofing?

Answer 54

Below grade foundations should be coated on the outside with a dampproofing agent

Question 55

What is waterproofing?

Answer 55

Concrete foundations subject to hydrostatic pressure must be waterproofed.

Question 56

How are pigments added?

Answer 56

During concrete mixing or may be shaken onto the surface of the concrete when the slab is being finished