Rather than attempting to erect the formwork and cast the concrete in place in a restricted setting it was decided that it would be easier to cast the concrete façade in the site yard on the horizontal and lift the individual elements into place by crane.
This allowed for the concrete to be placed through small openings left at either side of the 5/6m wide formwork. The shape of the façade rendered it impossible to compact the concrete by means of internal vibration.
As external vibrators could not be placed on the underside of the formwork it was also felt that external vibration would not sufficiently compact the concrete to produce a high-quality surface finish and the desired quality definition along edges and at corners/angles.
A self-compacting concrete (SCC) was chosen as being the only concrete type that could fully encapsulate the formwork and achieve the high-quality finishes as specified.
Through careful planning between the design team, contractors and the producer a design mix and placement methodology were agreed upon. An SCC concrete to a slump-flow class of SF2 was seen as the best option to achieve full encapsulation of the formwork and the desired quality of finish.
The concrete was placed through a tremie pipe that was immersed into the formwork. This placement methodology reduced the entrapment of air in the mix due to placement and reduced the volume of blowholes on the cast surfaces resulting in a high-quality finish.