Porous Cast

This research was fostered by an interest in the formation process of diatoms and radiolaria. Diatomes are unicellular or colonial algae. The cell is encased by a characteristic and highly differentiated cell wall, which is impregnated with silica. Radiolaria belong to the order of marine planktonic protozoans and feature a central protoplasm comprising chitinous capsule and siliceous spicules that are perforated by pores. The porous mass of the cell encasements of radiolaria and diatoms delivers an interesting model for differentiated cast walls in architecture that may feature a variety of specific performance capacities. The initial phase of the material system development focused on producing a skeletal framework articulated through the interstitial spaces left between pressurised containers, so-called pneus. A first series of experiments explored ways of casting plaster between air-filled cushions to achieve the typical shape of the mineralised skeletons between pneus that occurs in nature. A list of casting materials that feature different thermal characteristics was established. Physical experiments and digital analysis served to establish the possible range of light and airflow modulation relative to morphological features such as the size and density of pores and other characteristics of the material system. Subsequently a range of manufacturing approaches were tested, resulting in the production of a full-scale prototypical portion of the material system that integrated computer-aided manufacturing processes and pneumatic form-finding as a construction method. A approach finally chosen focused on strategizing a mould that would respond to the casting process and therefore deploy an element of material self-organisation. After several experiments with fabric moulds a rigid frame with an equally rigid back-panel was made. The back-panel supports an inflatable formwork, with pneus placed between two layers of rubber-sheet. The concrete was then cast between the two layers of rubber-sheet to fill the space between the pneus. An acrylic inlay in the frame allowed visual control of the casting process and the proper filling of the space between the pneus. The resulting cast is characterised by double-curvature, controlled porosity, and density and mass of the poured material. It can absorb thermal energy and release it to the airflow enabled by the porosity and the double-curvature can be utilised for thermal exposure or self-shading. Moreover, the artificial dichotomy between mass and lightness are brought into an interesting performative synergy.

AA Diploma Unit 4 (Michael Hensel, Achim Menges)
Gabriel Sanchiz, Architectural Association, London, 2005-06