Recycling Concrete Concrete can be recycled by grinding it up, using screens to separate materials, magnets to remove steel, and water flotation to remove unwanted materials. The recycled concrete can then be used for hardcore sub bases under new structures, gravel for paths or driveways, and as aggregate for new concrete. Recycling one ton of concrete could save 6182 liters of water and 900 kilograms of CO2.
Challenges in Concrete Recycling It's harder to recycle concrete if it contains lots of contaminants. Only about 30 percent of the materials in new concrete is recycled because its performance may otherwise be reduced. New processes using chemical additives can help break down old concrete into sand gravel and limestone while sequestering 60 kilograms CO2 per ton.
Innovative Approaches Researchers at Tokyo University have suggested a new kind of calcium carbonate-based concrete inspired by aquatic organisms hardening into fossils over time. They extract calcium from discarded concreate combine it with carbon dioxide from industrial exhaust or even from the air making a high-quality calcium carbonate-based cement.