The definition of aleatory is from the Latin word alea, meaning “dice,” and connotes that some element of a project is left to chance. This appears contrary to the traditional view of architecture and structural design in which little is left to chance.
Some designers are looking at new ways to design structures that takes advantage of randomness. Rather than relying upon traditional columns and arches to bear loads, building materials and components can be designed to adapt to find their own responses to structural and spatial contexts. Granular materials rely on force chains between adjacent particles inside the materials which are set up when the material becomes jammed. Until now, the shape of structures designed in this manner has been limited by the properties of the materials used. This limited method, using sand, stone, and gravel, has been used for years for retaining walls, dams, and breakwaters.
Recently, however, materials scientists have been experimenting with more complex, non-spherical particle shapes which, when poured, jam more easily and form stable structures. Some are even self-strengthening under load. An example is a light, quickly deployable bridge constructed by engineers at the Delft University of Technology in the Netherlands. They poured material into an air-tight fabric container that was vacuum-packed, generating the pressure that caused the material to jam into the desired shape. This method of vacuum-jamming has been used for carports and shelters as well as an alternative to form work for concrete since it can be reshaped or reused rather than discarded. A brief abstract and technical paper on the project is available.
All of this is resulting in new ways to think about design, allowing architects to imagine the overall form and then determine how it can be achieved by pouring granular material into place. Eventually, the goal would be to envision the overall structure first and then work backwards to determine the shape of the particles needed to create the structure when poured. Then the shapes could be 3-D printed and poured into place where they would self-assemble. Benefits of this process include the speed of construction and more lightweight structures. Structures can also be easily reconfigured since the material can flow when the jam is released.
This new approach might allow design and construction to include rather than exclude elements of chance, with randomness and structural disorder resulting in improved function. Aleatory design will certainly result in new ways of assessing the standard of care of architects and engineers.