Slip formwork is a formwork system that moves slowly and continuously upward during casting, so that a tall concrete structure is formed in one uninterrupted operation. The form ‘slips’ upward on climbing rods by means of jacks while fresh concrete is fed in below.
Application
Slip formwork is used for tall structures with a constant cross-section:
- Silos and water towers — cylindrical walls that grow up in one pass.
- High-rise cores — stair and lift shafts pulled up first.
- Chimneys and piers — tall, slender concrete elements.
The concrete emerging at the bottom of the slip form must have hardened just enough to stand on its own without slumping. For this reason the casting rate, concrete mix and weather are carefully matched. The process often runs day and night, because stopping creates joints and weak spots. A related technique is climbing formwork, which is moved storey by storey instead of gliding continuously.
Related terms
- Formwork
- Concrete
- Climbing formwork
- Concrete casting
- Reinforcement
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