Granular Jamming of Loadbearing and Reversible Structures

Granular Material and Sustainable Construction
In this project, we demonstrate two innovative methods of granular jammable principles at an architectural scale. These methods avoid the traditional constraints of construction due to the requirement precise placing of building blocks and the non-reversibility of concrete.

To overcome the lack of reversibility or recyclability of traditional construction methods, recent investigations of material science have focused on granular jamming, a phenomenon of instant and reversible of change phase between solid and liquid. We explore a new type of architectural-scale granular jamming utilises loose rocks and strings to enable nearly instantaneous and reversible loadbearing construction through a solid-to-liquid phase-change. This type saves labour and energy of the construction processes.

The first method used a robotic fabrication system to deploy the string, creating confinement around the loose aggregates and controlling where the material solidified and where it remained as a liquid. By so doing, precise control over form and function was achieved. Through this method, non-regular and complex architectural structures composed of crushed rock and string could be realized directly through computational design. If it is necessary to reconfigure the material into different architectural structures, simply pulling the string to lose the aggregates. This method works with a large variety of aggregates, for instance, different building materials found in the local. It also increases the speed for fast and low-cost construction.

MiniJammed Structures scaled from 30cm-100cm tall and stood in different geometric ways. The legs always grew upwards together into a large solid design, accommodating the mass required to create a compressive force and needed to stabilize the assembly.

Fabrication by the lightweight UR5 Robot
These Mini Jammed Structures were fabricated with a lightweight robotic arm coupled with a string-laying end effector, mounted on a gantry system. To compensate for articulated geometries, such as sharp edges or overhangs, it was necessary to deploy the string in a continuous and circular way. Following this, a thin layer of aggregates (as calculated by computational design) was manually poured and packed with a concrete compactor. Through the packing process, the string altered its edges. When the weight of aggregates and the horizontal force of the string reached equilibrium, the material system achieved structural integrity. These structures were built from the ground up with the container extending incrementally following the vertical aggregation. Once the structure was fully assembled, the container was removed, revealing the final product.

At the end of the project, Mini Jammed Structures was dismantled by pulling the string, restoring the building material into a pile of rocks and a spool of string. We are continually improving speed, repeatability, scalability, and design freedom of granular jamming, aiming to build truly instant and reversible loadbearing structures.

Project credits: Fernando Cena, Georgia Chousou, Yao Wang, ZongRu WU.
This project was developed during three weeks called minijammed in ETH Zürich.
Supervisors: Petrus Aejmelaeus-Lindström, Gergana Rusenova, Jesus Medina.
Photo credits: Tom Mundy, Gergana Rusenova.