Concrete

Front 1

Four ingredients of concrete are:

Back 1

Portland cement

Fine aggregates

Course aggregates

Water

Front 2

Concrete is a mixture of:

Back 2

Cement paste and aggregate

Front 3

Cement paste fills voids and acts as a ____

Back 3

Glue/binder

Front 4

Aggregates are precisely proportioned in order to:

Back 4

Reduce the amount of cement paste needed

Front 5

Excessive cement paste results in:

Back 5

-Better workability

-High shrinkage

-Expensive batch

Front 6

Insufficient paste results in:

Back 6

-Entrapped air

-Weaker and increased porosity

Front 7

The chemical reaction that happens when water and cement are mixed is:

Back 7

Hydration

Front 8

Applications of type 1 (normal) cement:

Back 8

General construction such as floors, foundation walls, sidewalks, high rise structures

Front 9

Applications of type 2 (moderate) cement

Back 9

Moderate danger of sulphate attack from ground water. Generates less heat. Massive concrete pours or hot weather

Front 10

Applications of type 3 (High early strength) cement:

Back 10

High Early Strength: used where fast curing is needed (highrise columns). Can be used in cold weather

Front 11

Applications of type 4 (Low heat of hydration) cement:

Back 11

Low heat of hydration: massive concrete pours (expansion and contraction is reduced furing pour)

Front 12

Applications of type 5 (Sulphate resistant) cement:

Back 12

Sulphate resistant: used for concrete exposed to high concentrations of sulphates in soil or ground water.

Front 13

Aggregates account for ____% of the total volume of concrete

Back 13

65% - 75%

Front 14

Fine aggregates are typically equal to ___mm or smaller

Back 14

5mm

Front 15

Coarse aggregates are larger than 5mm and typically between ___mm and ___mm

Back 15

10mm-40mm

Front 16

Increased aggregate gradation results in a reduced:

Back 16

Amount of cement paste required

Front 17

The maximum aggregate size of non-reinforced members (walls and footings) is:

Back 17

1/5 the smallest dimension

Front 18

The maximum aggregate size of unreinforced slabs on the ground is:

Back 18

1/3 the depth or thickness of the slab

Front 19

Maximum aggregate size of reinforced forms (foundation walls)

Back 19

3/4 of the spacing between the rebar and forms or the surface

Front 20

Maximum aggregate size in general construction is:

Back 20

20mm-25mm (3/4"-1")

Front 21

Most critical ratio of concrete:

Back 21

Water to cement

Front 22

Porosity is the:

Back 22

Ratio of voids in the concrete to the total concrete volume

Front 23

Excess water in concrete results in:

Back 23

Increased shrinkage and structural cracking

Front 24

Excess bleed water (water that gets pushed to the top of a pour) results in:

Back 24

Weak, chalky surface

Front 25

Mix ratio of finished concrete (floors, slabs or sidewalks) is:

Back 25

1:2:3

Front 26

1:2:3 ratio components:

Back 26

1 part cement to 2 parts fine aggregate to 3 parts coarse aggregate

Front 27

How many premix bags does it take to produce 1 cubic foot of concrete?

Back 27

3

Front 28

How many premix bags does it take to produce 1 cubic metre of concrete?

Back 28

36

Front 29

Concrete gains 50% of it's strength in:

Back 29

3-7 days after pour

Front 30

Concrete is assumed to be at full strength:

Back 30

28 days after initial pour