403A Concrete Formwork

Question 1

What is the primary cause of formwork failure during concrete placement?

Accepted Answer

Inadequate design for lateral fluid pressure of fresh concrete

Answer

Improper curing of the concrete

Answer

Using too many form ties

Answer

Incorrect placement of reinforcing steel

Question 2

How does the rate of concrete placement affect lateral form pressure?

Accepted Answer

Faster pour rates increase lateral pressure because the concrete doesn't set before more is added above

Answer

Faster pour rates decrease pressure because vibration dissipates energy

Answer

Pour rate has no effect — only height determines pressure

Answer

Slower pour rates increase pressure because the concrete has time to slump

Question 3

What is the purpose of form release agent (form oil) applied to formwork before a concrete pour?

Accepted Answer

To prevent concrete from bonding to the form so it can be stripped cleanly

Answer

To waterproof the form for reuse in wet conditions

Answer

To reduce concrete shrinkage during curing

Answer

To lubricate the form ties for easier removal

Question 4

What is the function of snap ties (form ties) in wall formwork?

Accepted Answer

To hold the two faces of the form apart at the correct wall thickness and resist the spreading force of concrete pressure

Answer

To connect form panels vertically for wall height

Answer

To attach walers to the form panels

Answer

To anchor the form to the ground against uplift

Question 5

What is the purpose of chamfer strips in formwork?

Accepted Answer

To create beveled edges on concrete corners that resist chipping and improve appearance

Answer

To provide drainage channels for water during curing

Answer

To separate concrete pours at construction joints

Answer

To mark stud spacing on form panels

Question 6

At what minimum temperature must fresh concrete be maintained during cold weather concreting in Canada?

Accepted Answer

10°C for the first 3 days after placement

Answer

5°C at time of placement only

Answer

15°C throughout the curing period

Answer

0°C — freezing is only harmful before initial set