Eggshell Brick
We take eggshells from food waste, clean them, separate them from the membrane and grind them to powder. The powder replaces part of the cement in a cement brick. The bricks are shaped in moulds and harden as they cure, with no kiln firing. We have completed compressive-strength and density tests. Eggshell bricks suit landscaping and planter edges, and can also be used as display bricks.
Feedstock: eggshells
Eggshell is a common food waste, made up mainly of calcium carbonate. The eggshells we use come from food-industry waste.
There is a membrane on the inside of the shell. Before the shells go into bricks, they are cleaned and separated from the membrane.
How shell and membrane are separated
Common separation methods use heat, which takes a lot of energy. Our method uses no heat and has two parts:
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Physical: shell and membrane have different densities, which lets us separate them
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Biological: fungi digest the membrane
How it is made
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Collection: Eggshells are collected from food-industry waste.
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Cleaning and separation: The shells are washed and separated from the membrane by the method above.
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Drying and grinding: The shells are dried and ground to powder.
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Mixing: The eggshell powder replaces part of the cement and is mixed with cement, water and other materials.
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Moulding: The mix is shaped in moulds.
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Curing: The bricks harden slowly as they cure. There is no high-temperature firing at any stage.
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Testing: After curing, the bricks are tested for compressive strength and density.
Testing
We made samples with several different proportions of eggshell powder and have completed compressive-strength and density tests.
Suitable uses
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Landscaping: decorative features and borders in gardens and outdoor green areas
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Planter edges: edging for planters and planting beds
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Display bricks: shown at exhibitions, education events and offices, so people can see food waste turned into a building material
Environmental benefits
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Food waste reused: Eggshells stay out of landfill and become a raw material for bricks.
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Less cement: Eggshell powder replaces part of the cement, so each brick uses less cement.
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No kiln firing: The bricks harden by curing, not by high-temperature firing.
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Separation without heat: Shell and membrane are separated by physical and biological methods, which saves the energy heating would use.
