The production of free formed concrete elements in a flexible mould

Evolution has proven that the microscopic geometry of the human bone (figure 1) is able to bear weights and at the same time to be light in weight. This quality, in combination with the attractive image of it, gave us a new field of interest for using this kind of morphology in a façade element. This type of element – free form - is an example of the forms that are pursued more frequently by contemporary architects. The growing interest for these free formed elements sparks the need for new approaches to production processes. The approach of the production process of free formed concrete elements has usually been influenced by the traditional method of casting concrete into stiff moulds. In most cases this has lead to very complex and labor intensive production processes resulting into rather irregular concrete surfaces. In this project a different approach towards casting concrete has been chosen to develop a less complex production method that moreover, results into smoother surfaces. To achieve this goal a mould has been made out of EPDM rubber. Sheets of this material were locally pressed together with wooden discs. In the process of casting concrete the elasticity of the material under influence of the concrete pressure leads to deflections. By being able to control these deflections up to a certain level, it is possible to produce elements that resemble the microscopic bone structure up to a satisfying level. The research that has been done has lead to a mockup of a façade element out of fiber reinforced concrete (figure 2). In this particular project a model resembling a bone structure was chosen, however the production process enables several forms and patterns resulting in double curved and smooth surfaces.