Transporting And Placement Of Concrete

Question 1

What happens if concrete is over-vibrated

Answer 1

Segregation of course aggregates

Question 2

What is max size of Aggs when pumping concrete

Answer 2

1/3 size of hoes

Question 3

When should forms be marked with pour height

Answer 3

After one side has been erected

Question 4

What material is used for expansion joints

Answer 4

Asphalt impregnated fibreboard

Question 5

What is used in the wet screed method

Answer 5

Concrete

Question 6

Who establishes legal location of buildings

Answer 6

Legal surveyor

Question 7

What truck is loaded with individual ingredients and mixes them together while on the way to site?

Answer 7

A ready mix truck

Pg. 13

Question 8

What is a cold joint?

Answer 8

A cold joint occurs when fresh concrete is placed against previously placed concrete that has already begun to set.

Question 9

Concrete should not be allowed to fall more then 1.5m? (True or false)

Answer 9

True, if concrete is allowed to free fall more then 1.5m it can cause the aggregate to separate from the paste.

Pg. 19

Question 10

Once the hydration process has begun, how much time do you have to place the concrete?

Answer 10

2 hours.

Pg. 14

Question 11

What factors influence hydro static pressure in fluid concrete?

Answer 11

•slump
•height of pour
•rate of pour
•ambient temperature

Pg. 22

Question 12

How much shrinkage is expected is expected within the first three months?

Answer 12

75% of total expected shrinkage

Pg. 24

Question 13

A truck that carries all ingredients to site and mixes them together on site is called a?

Answer 13

Mobile batch truck.

Pg. 14

Question 14

When is a Mobile batch truck needed over a regular truck?

Answer 14

When the location of pour is outside of the 2 hour placement window.

Pg. 14

Question 15

What’s the purpose of form watching?

Answer 15

To inspect and watch concrete forms for potential failure.

Pg. 25

Question 16

When should the wall form be marked with the pour height?

Answer 16

Once one side of the form has been placed.

Pg. 2

Question 17

How should an emersion be used?

Answer 17

It should be quickly lowered down through the fresh concrete at least 150mm into the previous lift and withdrawn slowly in and up and down motion.

Pg. 20

Question 18

If you’re mom’s vibrator is not available, consolidation is done by what?

Answer 18

Rodding or spading

Question 19

What two factors affect slump?

Answer 19

Water/cement ratio, and the addition of admixtures such as plasticizes and retards

Question 20

What increases as the height of concrete increases in forms?

Answer 20

Lateral pressure

Question 21

Standard mix of cured concrete may expand about ___mm per ___m of concrete length when subjected to a differential of 50°C.

Answer 21

5mm per 10m

Question 22

Pre-stressed concrete has the reinforce members ______ prior to the load of concrete being applied

Answer 22

Tensioned