Concrete (finishing, Joints, Prestressed, Precast)

Question 1

What’s the chemical process that hardens concrete

Answer 1

Hydration

Question 2

How long does concrete take to fully cure

Answer 2

28 days

Question 3

What type of broom is used to put a light texture on concrete?

Answer 3

Horse hair bristle

Question 4

Why is polyethylene barrier placed on the ground under concrete surface?

Answer 4

To stop water absorption into the ground

Question 5

Why are concrete toppings used?

Answer 5

True surface and abrasive resistant surface

Question 6

What direction do you bullfloat

Answer 6

Perpendicular to screeding direction

Question 7

If concrete is improperly cured, it’s strength may be reduced by up to what percent?

Answer 7

50%

Question 8

What is the name of the hand tool that is used to help level fresh concrete?

Answer 8

Darby

Question 9

After edging operation on a concrete floor slab, what is done next?

Answer 9

Floating

Question 10

When should curing begin

Answer 10

After finish troweling

Question 11

What effect does troweling have on concrete

Answer 11

Produces hard smooth finish

Question 12

Why are hardeners added to concrete surfaces

Answer 12

For Slabs with heavy traffic

Question 13

When should a heavy paper concrete stencil be used

Answer 13

After bull floating

Question 14

What type of tools should be used for air entrained concrete

Answer 14

Aluminum or magnesium

Question 15

What concrete surface is produced by spreading and embedding rock salt

Answer 15

Pitted surface

Question 16

When should dry shake hardeners/colour additives be used

Answer 16

When floating

Question 17

How long should a slab be kept moist after placement

Answer 17

72 hours

Question 18

What tool makes control joints

Answer 18

Jointer/divider

Question 19

What tool provides a slip resistant surface

Answer 19

Bristle broom

Question 20

Why are topping used

Answer 20

True and abrasive resistant surface

Question 21

How are joints between tilt up panels treated

Answer 21

Foam rod and caulked

Question 22

How tall can a tilt up building be

Answer 22

3 storys (typically used in single story warehouses)

Question 23

What type of connection can be used when a concrete beam meets on top of a column

Answer 23

Dowel type

Question 24

What makes wooden precast forms more durable

Answer 24

Two part epoxy resin

Question 25

Bracing angle for precast column

Answer 25

45-60 degrees

Question 26

What should not be used when patching prestessed concrete

Answer 26

Calcium chloride

Question 27

What’s the most common tie for securing bars against displacement

Answer 27

Single tie

Question 28

What tie is used for securing horizontal bars to vertical bars

Answer 28

Wrap and single tie

Question 29

What coats deformed bars to make them corrosion resistant

Answer 29

Epoxy

Question 30

Main purpose of welded wire mesh

Answer 30

Control temperature cracks

Question 31

Reinforcement for walls is usually built

Answer 31

Into the form work piece by piece

Question 32

What type of force would a smooth bar counteract

Answer 32

Shear

Question 33

Where are concrete restraints used?

Answer 33

In situations where concrete is likely to crack

Question 34

What material is typically used to create a bulkhead?

Answer 34

Lumber, Plywood, or Metal

Question 35

Minimum splice for Column reinforcement

Answer 35

20 bar diameters but not less then 300 mm

Question 36

Which tie system is most common for securing deformed bars in footing mats?

Answer 36

Saddle tie

Question 37

What is minimum splice for temperature bars in slabs

Answer 37

24 bar diameters but not less then 300mm

Question 38

What is one method to reduce the problem of shrinkage in concrete?

Answer 38

Use lowest water-cement ratio possible

Question 39

When reinforcing retaining walls, why is the main vertical reinforcing placed near the earth side?

Answer 39

So reinforcing is In tension

Question 40

What best resists diagonal shear in beams

Answer 40

Stirrups

Question 41

How many grades of strength do deformed bar come in?

Answer 41

3

Question 42

What is used to create a mechanical locked joint in a bulkhead

Answer 42

Rebar and keyways

Question 43

If a welded wire fabric has a designation of 8 x 12 - W24 x D16, it means that

Answer 43

It has smooth longitudinal wires at 8 inches on centre

Question 44

Most common materials used for expansion joints

Answer 44

Sponge rubber, expanded polystyrene, cork, plastic, or asphalt impregnated fibreboard

Question 45

In what order would an isolation joint be done around a column

Answer 45

Column poured, joint material is applied and then the floor is cast against it

Question 46

Recommended lap for welded wire mesh

Answer 46

One full space plus 50mm

Question 47

Best suited tie system for keeping bent bar in position

Answer 47

Saddle tie

Question 48

Controlling or minimizing concrete shrinkage is best done by

Answer 48

Using low water cement ratio, well gradded aggs, water reducing agents and curing it properly

Question 49

How far apart should transverse control joints in driveways and floor slabs be

Answer 49

5-6 metres

Question 50

What hand tool is used to produce a very smooth and hard-wearing surface to concrete during finishing

Answer 50

Steel trowel

Question 51

What is used with concrete stamps to give slightly rounded edges to the pattern

Answer 51

Polyethylene Sheeeeeet

Question 52

What effect does troweling have

Answer 52

Produces a hard smooth surface

Question 53

What type of curing allows work to continue on a slab as it cures

Answer 53

Liquid membrane

Question 54

When stencilling concrete, how should you keep from coloring the grout lines

Answer 54

Add dry shake color with stencil in place

Question 55

What will water-tightness, durability, strength and appearance largely depend upon

Answer 55

Proper curing of mix

Question 56

Which concrete finishing tool creates a number of parallel grooves at the nosing of the step?

Answer 56

Safety Step Edger

Question 57

When should fine textured broom finish be applied to a slab

Answer 57

After troweling

Question 58

What is the primary purpose of properly curing concrete

Answer 58

To minimize moisture lost

Question 59

When can a crane be unhooked from a tilt up wall

Answer 59

After plumbed and braces

Question 60

What protects inserts from filling with concrete past during a slab on grade pour

Answer 60

Plastic covers

Question 61

Double nuts are used to adjust precast concrete columns for elevation and plumb. What else is required to ensure the column can transfer compressive loads?

Answer 61

Non-shrink grout and shim packs

Question 62

What is placed on the slab-on-ground so tilt-up panel doesn’t adhere to slap

Answer 62

Releasing agent

Question 63

Forms made of which material are preferred for the repeated production of standard sizes and shapes

Answer 63

Steel

Question 64

How is extra strength provided to angle irons at the base of a column to prevent them from bending?

Answer 64

Add gussets to the inside angle

Question 65

What is used to adjust precast columns when they are placed on cast-in-place footings

Answer 65

(Deez)nuts below the baseplates

Question 66

For the placement of reinforcement for large precast concrete items, how are the form sides moved apart to provide workspace?

Answer 66

Wheels that run on rails

Question 67

What type of defect shows up on the surface of concrete slabs if they rapidly dry out?

Answer 67

Plastic cracks caused by shrinkage