Slipform Construction

Slipform

Slipform - concrete is placed continuously in side form which moves at a group rate. Forms aren't removed; they slip over the concrete which may support itself by the time it's out of the shape . Slipform System; Electro-Hydraulic self-climbing system; may be defined as a method of continuously moulding or forming concrete, with the utilization of a moving formwork.slipforming, the ability of concrete to stand safely and unsupported within 2 to 4 hours after being placed into the formwork in a plastic state. An evolution of the tactic has been happening gradually over the years by fabquip Construction Systems.

The rate of movement or slipping, is controlled by the setting or curing rate of the concrete, which must be capable of supporting a minimum of its own weight when exposed by the moving formwork. This is undoubtedly the most unique aspect of

Uses:

Construction of reinforced concrete wall structures such as silo complexes, chimneys, reservoirs, medium to high-rise housing, office buildings, hotels, hospitals, bridge piers, in ground shafts, caissons, dam structures, power stations etc.

The following are the major components of slip form System: 

• Shuttering/form panels.
• Walers
• Yokes
• Working decks
• Hanging scaffolds
• Truss system
• Hydraulic jacks
• Jack rods
• Pumping units for jacks
• Bracings
• Operation screws
• Extraction jacks
• Miscellaneous equipment.

The Working system of Slipform

Each layer is vibrated with high frequency immersion type vibrators.
In commencing any slipform project, the forms must first be filled by layering within the concrete as described above.
The formwork, in the least times, must be kept as filled with concrete as possible to permit the concrete the utmost period of your time within the forms to realize strength before being exposed beneath the sliding forms. As the forms are slid or jacked upward, concrete continues to be layered into the highest of the forms.

The speed of jacking is decided by the setting characteristics of the concrete instead of by the speed of the jacking system. If jacking is just too fast, plastic concrete will fall out because it is exposed from rock bottom of the forms. Conversely if jacking is just too slow, the concrete surface will become dry, generating considerable friction between the sliding faces of the formwork.
Jacks are used to lift the formwork. They climb on jack rods, which are located centrally in the wall and cast into the concrete, the concrete providing lateral restraint against buckling of the jack rods.
Additional jack rods are added with the help of screwed end couplings because the formwork rises.
The horizontal reinforcement has got to be threaded beneath yoke heads because the slipform rises.
Slipforming is generally undertaken on repetitive work where speed or economy through the utmost reuse of an equivalent formwork is feasible .
Slipforming are often administered continuously, 24 hours each day until the structure is completed; alternatively slipforming are often done on a discontinuous basis during daylight only; i.e. high-rise core construction.
Continuous Slip forming is normal for the development of silos or water retaining structures where monolithic walls are required. On such projects, slipforming are often administered at a mean speed of 300 to 400mm tall per hour.

Discontinuous slip forming

Discontinuous slip forming is preferred for multi-story structures such as apartment building and commercial offices. For projects of this type, it is normal to use slipform for one full floor height per day (i.e. 3 to 4 meters). The following day is employed to put in window, door and floor blackouts, fix all vertical reinforcement, install stairs and usually make ready for subsequent floor height pour which would be completed the following day.
There are many factors which can influence the choice to slipform continuously or discontinuously. For instance, where a slender or complicated structure is to be slipped, the speed of strength gain of the concrete and stability considerations, particularly where strong wind conditions are encountered, will dictate that a discontinuous or intermittent slipform approach be adopted.

Custom assembled to designed specifications

It is possible to slipform quite complex shapes. Almost any rectangular, cellular, curved or convolute d shape are often slipped.
Whilst this is often a desired requirement, it shouldn't be taken as a limiting factor because it is sort of possible to vary wall thicknesses and to feature to or remove walls from a Slip form during construction.
Where projections from the wall face need to be provided as an important a part of the structural design, like corbels or haunches to supply seating for precast beams or panels, then these are often formed integrally with the slipformed wall by the utilization of static formwork panels. These remain stationary in situ because the slipform rises. This type of detail tends to complicate a slipform and intrinsically should only be used where no alternatives are structurally or economically possible.
slipform construction may be a method for building large towers or bridges from concrete. The name refers to the moving form the concrete is poured into, which moves along the project because the previously poured concrete hardens behind it.
Concrete must be workable enough to be placed to the shape work and powerful enough to develop early strength in order that the form can slip upwards with none disturbance to the freshly placed concrete.