Vertical slipform systems
Slipform systems are similar in nature and application to jump form systems, but the formwork is raised vertically by hydraulic jacks in a continuous process. It is a method of vertically extruding a reinforced concrete section and is suitable for core walls in high rise structures, such as lift shafts, stair shafts and towers. They are self-contained systems that require little crane time during construction.
The systems can be used to form any regular shape of core. The formwork rises continuously at a rate of about 300mm per hour, supporting itself on the completed core, as the concrete is cast. Commonly the formwork systems have three platforms. The upper platform acts as a storage and distribution platform while the middle platform, which is the main working area, is at the top of the poured concrete level. The lower platform provides access for concrete finishing. All necessary guard rails, ladders and wind shields are built into the system.
Further information may be found in Formwork for modern, efficient concrete construction, by Rupasinghe and Nolan, published by BRE Press and the publication listed.