Slip forming

[1] Slipforming enables continuous, non-interrupted, cast-in-place, cold joint- and seam-free concrete structures that have performance characteristics superior to those of piecewise construction using discrete form elements.

On May 24, 1917, a patent was issued to James MacDonald of Chicago, "for a device to move and elevate a concrete form in a vertical plane".

In the 1947-1950 period, MacDonald Engineering constructed over 40 concrete towers using the slip-form method for AT&T Long Lines[7] up to 58 m (190 ft) tall for microwave relay stations across the United States.

Another shear wall supported structure was the Casa Del Mar Condominium on Key Biscayne, Miami, FL in 1970.

From the 1950s, the vertical technique was adapted to mining head frames, ventilation structures, below grade shaft lining, and coal train loading silos; theme and communication tower construction; high rise office building cores; shear wall supported apartment buildings; tapered stacks and hydro intake structures, etc.

In addition to the typical silos and shear walls and cores in buildings, the system is used for lining underground shafts and surge tanks in hydroelectric generating facilities.

The first residential building of slipform construction; erected in 1950 in Västertorp , Sweden, by AB Bygging
Later picture of the residential building in Västertorp
Slipforming of a 118 metre-tall grain silo in Zürich in 2015
Continuous slip formed gravity-based structure supports under construction in a Norwegian fjord . The visible jib cranes would be delivering buckets of concrete to the support cylinders during the continuous pour of concrete creating seamless walls.
Slipform monobox system
AT&T Long Lines relay tower in Indiana constructed with the slip-form method
Two coal silos being constructed by slip forming