Demolished concrete

Breaking Ground: a research project

Breaking Ground is a self-initiated research project by Georgia Stevenson that explores the potential of construction and demolition waste in ceramics. Rooted in process-driven research, it tests unconventional materials as alternatives to extracted and mined finite minerals. The project also investigates material provenance, our attachment to place, and the meanings embedded in site-specific materials.

Demolished concrete, collected as debris and rubble from construction and demolition sites, is found in abundance across urban environments. The physical characteristics of demolished concrete—irregular sizes, heavy weight, and logistical challenges—often lead to its downcycling. It is typically crushed into Recycled Concrete Aggregate (RCA) and used as road base material, effectively ending its recycling journey.

While some studies explore the incorporation of demolished concrete in fired bricks, ceramic tiles, or composite construction materials, its application in ceramics studios remains underdeveloped. Anecdotal accounts suggest concrete should be avoided in studio practices due to issues like “lime pop-outs,” which compromise traditional ceramic surfaces.

For the Breaking Ground research project, demolished concrete is broken down through a labor-intensive process and reconstructed with precise formulations. The resulting explorations, in the form of test tiles, wall hangings, and various vessels, highlight the versatility of concrete in clay bodies, glazes, and as a standalone material. The exact chemical composition of demolished concrete varies depending on its source, resulting in diverse and sometimes surprising outcomes when fired.

Concrete in Glazes:
Cement and fine sand particles act as stabilizers, while larger rock aggregates contribute fluxes or iron content. Colour range can vary from green to orange-brown and some samples have produced amber-gold crystal growth within the glaze.

Concrete in Clay Bodies:
When integrated into clay bodies, concrete can provide speckles similar to trachyte and ilmenite. At higher and more experimental levels, concrete can replace clay entirely, necessitating alternative forming techniques due to its non-plastic nature.
Georgia Stevenson continues to expand on the possibilities of concrete in ceramics, embracing innovative techniques and methods outside of the scope of traditional ceramic practices. The work explores the material's behavior, aesthetic potential, and adaptability. These experiments challenge the perception of concrete as a utilitarian material, reimagining it as a medium for creative expression with varied textures, colors, and finishes.

Making process

Demolished concrete debris is collected from local construction and demolition sites, as well as large-scale recycling facilities. The concrete is sorted to remove other materials, particularly plastics and organics, that could melt or release fumes during firing. In some cases, the concrete may be calcined to simplify processing. It is then crushed and sieved into various particle sizes.

The prepared material can be incorporated into glaze recipes, wedged into a clay body, or used as a standalone material.

Note: All photos depict pieces fired to midfire temperatures in an electric kiln. Additional tests have also been successfully fired at stoneware temperatures.

Handling demolished concrete can pose unknown hazards depending on the collection site. Safety precautions are essential. Research site history, including council planning records, soil contamination reports, and potential heavy metal toxicity, where available. Use a respiratory mask when crushing and sifting dry material to protect against silica dust, and consider wearing gloves as an added precaution. Ensure the kiln is well-ventilated to minimize exposure to fumes.

Text submitted by the maker and edited by the Future Materials Bank. For information about reproducing (a part of) this text, please contact the maker.