Title: Innovative Techniques-Construction of In-situ Post-Tensioned slabs, without Conventional Formwork

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Publication: CIA

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Date: 2/13/2011

Abstract:
A new approach to the construction of cast in-situ post-tensioned slabs has been developed which removes the need of conventional formwork. Since 1995, VSL have been involved in the development of the Climbfloor construction system in conjunction with the systems inventor and C.E.O. of Jacking Systems Ltd New Zealand. In a typical application of this system, each slab is cast on top of the previous slab then lifted into place by a multi-point synchronised jacking system. High accuracy, to within 0.1mm of each control point is achieved through a synchronised and automated mechanical lifting system. Slab lifting speed is approximately 1.5mm/s, with a typical 2.7m floor to floor slab lifted in 30 minutes. The load is suspended at each jack on a mechanical ball screw and moved by the rotation of variable speed drives. The system provides its own freestanding vertical support system, with its own back props allowing the system to self-climb to higher levels without crane assistance. The system also includes a fully self-contained, self-climbing safety system, inclusive of catch screens, walkways and handrails, as shown in figure 2.