Slip-form Rig
The lifting rate (or speed) of rig is determined by the slip-form technician and is based on speed of the placement of the concrete and reinforcement as well as the setting time of the concrete. Careful monitoring of the position of the slip form allows the hydraulic jacking system to control of the plumb of the finished concrete.The design of the slip form allows for any twisting to be countered.
Openings with varying wall thicknesses and cross-sections can be accommodated and all contribute to an acceptable lifting rate. The slip-form rig typically comprises three levels of working:
1) Upper reinforcement deck
The reinforcement deck is the uppermost deck on the slip-form rig and facilitates the fixing of the reinforcement. Some slip-form rigs combine the reinforcement deck with the middle working deck.
2) Working deck
The working deck is the main deck of the slip-form rig. Typically this deck will support the hydraulic jacking system and provides the working platform from which to place and compact concrete.It is important that the concrete is placed in even layers around the formwork shutters. The control of the concrete quality, supply and setting rate is vitally important for slip form operations.
3) Lower rubbing up deck
The rubbing up deck is located under the working deck and provides access to the faces of the poured concrete as they emerge from the underside of the shutters. The concrete is made good from this deck to provide a smooth surface finish. |
