Global Holcim Innovation 3rd prize 2012

Efficient fabrication system for geometrically complex building elements, London, UK

Type of project:	Materials, products and construction technologies Start of production:  not applicable
Main author:	Povilas Cepaitis, AA School of Architecture, United Kingdom
Further authors:	LLuis Enrique, Diego Ordoñez and Carlos Piles, AA School of Architecture, United Kingdom

Project description
Cast on Cast, efficient and sustainable fabrication process is focused upon the development of a smart but simple methodology to design and prefabricate building elements with complex geometries, which is resource efficient and considerably reduces construction waste. Complex geometries are utilized in contemporary architecture for the construction of concrete or mortar building envelopes, partition walls, horizontal and vertical shading elements and pavements. Building elements that are curved through all three dimensions can only be produced under current methods by using sophisticated formwork installations and highly industrialized prefabrication technologies at high cost. The proposed Cast on Cast methodology uses a parameterization system in which mathematical algorithms subdivide three dimensional elements into smaller components that can be stacked in towers. Furthermore the previous element is used to mold the shape of the subsequent element. This CNC controlled fabrication method relies on the consecutive process of casting elements using digital fabrication technology. These towers of elements are then transported to the site where they are detached and assembled into the desired spatial shape.

This innovative system integrates construction parameters directly into the design stage to ensure the efficiency and sustainability in the subsequent realization stages. This is possible thanks to a set of mathematical algorithms (a-b-b-c, overlapping, angle, hexagon and triangle), which subdivide the input surface into stackable elements, and extract their coordinates to proceed with the fabrication stage. This new manufacturing system does not require additional molds as each component is formed by using the previous one as mold. This idea of production is materialized by digitally injecting layers of a viscous material inside a vertical container.

Despite the components having non-standard curved geometries, they can easily be accumulated in regular stacks. This feature is advantageous for their storage and transportation since the components use the space in the most efficient way, reducing time and pollution involved in these stages. The specific geometry of the components avoids the need of formwork, minimizes the amount of work in the construction site and reduces the amount of waste.

Image gallery
Efficient fabrication system for geometrically complex building elements, London, UK
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