Concrete is the most abundant man-made material on earth. There's a good chance you're standing on it right now, and it's holding up the buildings around you. But concrete has an emissions problem. Its essential ingredient, cement, has a huge carbon footprint. This concrete traps CO2 emissions forever
Cement is the glue that makes concrete strong, but the process of making cement requires superheating calcium carbonate, or limestone, and releases massive amounts of carbon dioxide into the atmosphere.