Climbing formwork “climbs” one pour at a time: once a lift of concrete has cured, the formwork system is struck, lifted and anchored to the concrete that was just cast below it. That way a wall, core or pier is built upwards lift by lift, without needing scaffolding or propping all the way from the ground.
There are two main variants. With crane-handled climbing formwork the tower crane lifts the unit to its next position. With self-climbing formwork, hydraulic jacks do that, pushing off climbing cones cast into the concrete; that variant is crane-independent and therefore insensitive to wind and crane availability.
Difference from slipform
| Climbing formwork | Slipform | |
|---|---|---|
| Method | in stages, one lift at a time | continuous, pouring day and night |
| Height per stage | usually about 2.5 to 4.5 m | continuous, several metres a day |
| Joints | a horizontal construction joint per lift | virtually seamless wall |
| Flexibility | cross-section can change per lift | cross-section essentially constant |
| Organisation | normal working days | shift work, cannot be interrupted |
Where it applies
- Lift cores and stair cores in high-rise
- Bridge piers and pylons
- Silos, shafts and cooling towers
- Retaining walls and tunnel walls requiring tall, continuous concrete faces
Points to watch
- Concrete strength before climbing — the system may only be re-hung when the concrete below has reached the strength specified by the engineer; that is the safety-critical step
- Climbing cones and anchors — the anchor points are cast in and form part of the structural calculation; they must never be improvised
- Construction joints — every lift leaves a horizontal joint; on fair-faced concrete their position and execution determine the appearance. Set the joint pattern out on drawings beforehand
- Edge protection — the climbing platform is the working deck; guardrails, toe boards and a closed trailing platform are part of the system
- Weather and wind — lifting large formwork units is wind-sensitive; self-climbing systems have a clear advantage here
- Not DIY work — climbing formwork is proprietary system formwork with its own assembly instructions and supervision requirements
Related terms
- Formwork
- Slipform
- Concrete
- Formwork release agent
- Step irons
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