What is striking formwork?
Striking (also called stripping or striking formwork) is the removal of formwork (shuttering) after the poured concrete has developed sufficient strength to support itself. The formwork — the temporary mould into which concrete is cast — is only removed once the concrete is self-supporting.
How does striking work?
Formwork gives liquid concrete its shape and carries the load until the concrete has hardened. Striking is carried out in stages:
- Observe minimum striking times — depending on the element, temperature and cement type, this is at least 1 to 7 days (longer for load-bearing elements)
- Remove side formwork — non-load-bearing sides can be removed first
- Remove supports — props and load-bearing formwork are removed last
- Inspect — the concrete surface is checked for defects such as honeycombing or cracks
When can you strike?
- Non-load-bearing parts (sides) — after approximately 1–2 days
- Load-bearing slabs and beams — after at least 7–28 days, depending on the span
- In cold weather — striking times are extended because concrete cures more slowly
Applications
- Concrete slabs and soffits — props remain until the concrete reaches the required strength
- Foundations — side formwork is removed relatively quickly
- Columns and walls — formwork is removed in sections
- Precast — in the factory, formwork is struck quickly thanks to accelerated curing
Related terms
- Formwork
- Concrete
- Props
- Curing
- Setting
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