Turbulent Casting: Bacterial Expression in Mineralized Structures

There has been a growing interest in living materials and fabrication processes including the use of bacteria, algae, fungi and yeast to offer sustainable alternatives to industrial materials synthesis. Microbially induced calcium carbonate precipitation (MICP) is a biomineralization process that has been widely researched to solve engineering problems such as concrete cracking and strengthen soils. MICP can also be used as an alternative to cement in the fabrication of building materials and, because of the unique process of living fabrication, if we see bacteria as our design collaborators new types of fabrication and process may be possible. The process of biomineralization is inherently different from traditional fabrication processes that use casting or molding. Its properties are influenced by the active bacterial processes that are connected to the casting environment. Understanding and working with interrelated factors enables a novel casting approach and the exploration of a range of form types and materials of variable consistencies and structure.

We report an experiment with partial control of mineralization through the design of different experimental vessels to direct and influence the cementation process of sand. In order to capture the form of the calcification in these experiments, we have analyzed the results using three-dimensional imaging and a technique which excavates the most friable material from the cast in stages. The resulting scans are used to reconstruct the cementation timeline. This reveals a hidden fabrication/growth process. These experiments offer a different perspective on form finding in material fabrication.