Mollusk Masonry

︎ Creator: Sofia Castano        
︎ Supervisor: Peter Yeadon


For this biomaterial project, I knew I wanted to experiment with using mollusk shells, such as mussel, oyster, and clam shell as the foundation of my exploration. I conducted initial research on shells in the local region of Rhode Island and learned that most are sent to landfills after the meat is consumed at restaurants. I also recognized that the inherent qualities of shells would make them strong candidates for material experimentation. Although I did not have a clear idea for the final artifact at the beginning, I knew I wanted to emphasize and explore the natural properties of shells through biomaterial development.

To source the shells, I visited local restaurants and asked for their waste scraps. During this process, I learned that shells are typically thrown away or, composted. Before using them in my experiments, I prepared the shells by boiling, baking, and crushing them into a fine powder. Through this process, I found that mussel shells were the easiest to prepare and grind, while clam and oyster shells were much harder and took significantly longer to crush. For time saving purposes I bought oyster shell powder to ease the laborious process.

During the experimentation phase, I used a variety of recipes from the Materiom website as a starting point for my explorations. I discovered that sodium alginate worked best as a binder, particularly when combined with shells of varying grit sizes, rom very fine to semi-coarse. However, it did not perform well in terms of water resistance. As a result, I continued experimenting to enhance the water resistance of the material. I tested ingredients such as xanthan gum, glycerol, agar agar, and chitosan.

After many trials, I developed two successful recipes. The first was a thermoplastic starch composed of water, shell powder, glycerol, starch, and vinegar. This mixture created a moldable, clay-like material that could easily be formed into shapes and adjusted or cleaned with water. The second recipe was a self-reinforced concrete made from alginate, chitosan, water, shell powder, collagen, and gelatin, activated with a calcium chloride spray. This material was also water-manipulable, making it ideal for 3D printing or, in my case, piping from a bag.

Given the final properties of these materials and my background in architecture, I decided to create a ceramic brick at an architectural scale. Using the second recipe, I was particularly interested in exploring the possibilities of “3D printing” and the forms and patterns it could produce.

With Recipe #1 (thermoplastic starch), I created brick-like forms featuring different negative interior shapes to explore the material’s strength, flexibility, and ability to form hollow structures. These bricks measured approximately 4 inches by 4 inches with a thickness of 2 inches, resulting in solid yet easily moldable component. With Recipe #2 (self-reinforced concrete), I explored 3D printing techniques by piping lines, squiggles, and circles in layered formations. Eventually, I returned to the biobrick concept, using the piping method to form square shapes while highlighting the layered nature of the “printed” material.

In the final step, I sprayed the structure with a calcium chloride solution, commonly used to de-ice roads, which acted as the setting agent. This spray reacted with the chitosan, helping to solidify each layer as additional material was applied. This process made it possible to build multiple layers without the structure collapsing under its own height, which the result was a strong, solid block that dried successfully.

My hope for this project is to eventually replace concrete as a building material and transform shell waste into a valuable resource. While this goal may be ambitious, I believe the material has strong potential at smaller scales such as interior walls and surfaces, furniture components, objects requiring frequent replacement, or stationary items like lamps or vases. I am also aware that this biomaterial is designed to degrade over time. With this in mind, it could be used to create biodegradable plant pots that slowly break down with water exposure, releasing seeds and nutrients to support plant growth. The resilience and versatility of shells offer many possibilities, both biodegradable and permanent, making this an exciting way to transform waste into something purposeful and meaningful.