Slip formwork system and its advantages
Slip forming, continuous poured, continuously formed, or slipform construction is a construction method in which concrete is poured into a continuously moving form. The slipform technique of construction allows for the continuous pouring of concrete into walls of a structure and only stops when the full required height of the structure has been reached. The name refers to the moving form the concrete is poured into, which moves along the project as the previously poured concrete hardens behind it. Cement, and concrete by its association with it, has an initial setting time of just about thirty minutes, after which the cement and the concrete have gained sufficient strength to remain in the shape into which it has been poured.
Slipforming enables continuous, non-interrupted, cast-in-place “flawless” (i.e.no joints) concrete structures which have superior performance characteristics to piecewise construction using discrete form elements.
Slip forming was initially devised and utilized in the Interstate Highway building binge of the Eisenhower administration during the 1950’s. The height of the formwork is designed in such a way that while the top of the formwork is being filled by concrete the lowest layer of concrete poured earlier has already gained an initial set.
In vertical slip forming the concrete form may be surrounded by a platform on which workers stand, placing steel reinforcing rods into the concrete and ensuring a smooth pour.
Advantages of slip form
- High speed of erection (works’ execution speed increases) and as a result, rapid completion of the project – considerable saving of time;
- Rapid completion of the elevator machine room constructing process, time saving through quick installation of elevators, installation of water and electricity supply
- Minimal use of a crane, as formwork is lifted by hydraulic jacks
- Optimal quantity of scaffolding and work platforms as the slip formwork system presupposes the use of its own platforms for implementation of works. This helps to maintain cleanliness and order at theconstruction site, because there is no redundant material to be stored
- Uniformity of wall sections with the project drawings, smooth wall surfaces are achieved by the use of slip formwork, which cannot be said about other formwork systems
- Reduced labor costs due to the intensity of the working process.