Slipforming is a civil engineering construction method in which a continuously moving formwork is used to cast a concrete structure, such as a tower, silo, dam wall or road pavement, in one continuous pour rather than in separate sections. The form is raised or advanced gradually, typically by hydraulic jacks climbing a set of vertical rods, at a rate matched to the concrete's curing so that the material has enough strength to support itself as it emerges from the bottom of the form. Slipforming produces a seamless structure without the construction joints that section-by-section pours leave, and it has been used to build tall concrete towers, grain elevators and the elevator and stair cores of high-rise buildings.
Facts
Core PrincipleConcrete is placed into a form that stays in continuous motion, moving horizontally along the ground for pavement and curbs or raised incrementally by hydraulic jacks for vertical structures, so the finished structure is a single continuous cast in place pour with no cold joints or seams between sections. 1 Origin YearJames MacDonald of MacDonald Engineering in Chicago pioneered the technique for circular grain bins, publishing the concept in a 1907 book and a 1910 paper before the patent issued. FAQs
How is slipforming different from jump forming?
Slipforming raises the form continuously while the concrete is placed; jump forming moves it in separate steps after each section has set.
Both methods use formwork that climbs a concrete core or shaft as it is built, but they differ in how the form moves. In slipforming the formwork is a continuous pour system: a self-climbing form supports itself on the core or shaft being constructed and moves slowly up over the concrete as it is cast. Jump forming progresses in a series of steps, or jumps, and moves on to the next section only after the concrete in the previous one has gained the necessary strength. In one example a 2 metre section is poured and set, and then the formwork is jumped to pour the next 2 metre section. Because jump forming leaves joints between jumps, it suits situations where those joints will be concealed, for example by the floors of a building.
Connections
Associated With
Concrete, Materials Slipforming casts concrete continuously in a moving form for tall or long structures.
In Field
Source Slip Forming (Wikipedia)Wikipedia contributors
Sources
1. Slip Forming (Wikipedia)
Wikipedia contributors, Wikimedia FoundationLead section
a construction method in which concrete is placed into a form that may be in continuous motion horizontally, or incrementally raised vertically
History section
On May 24, 1917, a patent was issued to James MacDonald of Chicago
In Field: Civil Engineering, Categories
Civil engineering
In Group: Tunnelling, Foundation and Concrete Construction Methods, Introduction
Slip forming, continuous poured, continuously formed, or slipform construction is a construction method in which concrete is placed into a form that may be in continuous motion horizontally, or incrementally raised vertically.
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