Cast thicket by Kenneth Tracy and Christine Yogiman of yo-cy.

Photo:Kevin MCClellan.

Cast Thicket is the winning proposal designed by yo-cy for an advanced structures competition run by the University of Texas. It is a study in tensile concrete. The aim was to make a heavy material look lacy, thin and delicate, so inverting the perception of concrete as a carved monolith.

The structure for the formwork was created using steel nodes connected by 44 thin struts. Wrapped around this is a skin that will retain the concrete until it cures. It is made from a plastic film, tied together using plastic cable ties. It will deform under load giving a rippled texture to the concrete something like a fabric form-work. The struts remain to become the reinforcement.

The concrete itself is an interesting mixture. The designers wanted a light colour and a lightweight structure. They used light colour aggregates, including limestone powder with white fibre reinforcement. Poraver glass beads were also used to reduce weight with metakaolin, a material used to make porcelain. A super-plasticiser was used to help the mixture flow by reducing its viscosity.

The experiment explores the application of advanced CAD modelling techniques and their application in fabrication.

Photo:Kevin MCClellan.

Photo: Details Christine Yogiman.

Fab 1: Thin steel struts welded to nodes forms the skeleton. (Kenneth Tracy)

Fab 2: Plastic skin provides the formwork. (Kenneth Tracy)

Fab 3: The formwork is cut from individual sheets of plastic with tabs to tie it together. (Kenneth Tracy)

Fab 4: The plastic formwork is held together with plastic cable ties. (Kenneth Tracy)

Fab 5: Cast Thicket used a plywood scaffold. (Kenneth Tracy)

Fab 6: The designers opted for a bespoke lightweight concrete mix that was also light coloured. (Kevin McClellan)

Gratitude to AN blog.