Why it matters
Formwork questions cover form pressure, ties, bracing and when forms can come off. The key idea is that fresh concrete acts like a heavy liquid until it sets.
Key points
- Lateral pressure rises with pour rate and pour height, and falls as the concrete gets warmer.
- Form ties hold the two faces together against that pressure. Their spacing comes from the tie rating.
- Bracing keeps forms plumb and aligned. It does not carry the liquid pressure.
- Release agent goes on before the steel is placed so it does not coat the rebar.
- Stripping time depends on strength, temperature and the engineer's instructions, not a fixed number of days.
Study tip
If a question asks how to cut form pressure, look for a slower pour rate.
Try these
Pouring a wall faster will:
- Lower form pressure
- Raise form pressure
- Not change pressure
- Only affect slabs
Show answer
B. Raise form pressure Faster pours leave more liquid concrete in the form.
What holds opposite wall form faces together?
- Kickers
- Form ties
- Walers alone
- Strongbacks
Show answer
B. Form ties Ties resist the outward pressure.
Release agent should be applied:
- After rebar is placed
- Before rebar is placed
- After the pour
- Only on steel forms
Show answer
B. Before rebar is placed Keeps oil off the reinforcing steel.
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