Reactors of various sizes spread across five laboratories at DTU Lyngby Campus might hold the secret for saving nonrecyclable building materials from being sent to landfill, turning them into new building materials instead. The method is the brainchild of DTU Professor Susan Stipp.
In a nutshell, it uses waste stone wool (fact box below) and crushed waste concrete in water, in containers, where CO2 and a patented mix of specially developed, natural molecules are added.
The waste building materials, which are alkaline, are converted into a fine-grained product containing calcium carbonate and other minerals.
The product collects as sediment in the containers—much like the scale that collects at the bottom of a tea kettle when you boil water. This solid material has properties that make it suitable as an ingredient in concrete. It can partially replace cement, which has a large carbon footprint (fact box below).
"Concrete made using this product will probably not be strong enough for constructing tall buildings, but could be used to make paving stones with a smaller carbon footprint," Susan Stipp says.
