The Greening of Concrete

Researchers are working on ways to slash carbon dioxide emissions associated with the production of concrete and even to develop forms of the material that can sequester CO2, The New York Times reports. The manufacturing of Portland cement, a key ingredient in concrete, accounts for 5 percent of human-caused greenhouse gas emissions because limestone and other cement components must be heated to 2700° F. Scientists and engineers are now replacing much of Portland cement with fly ash from coal-powered power plants or slag from blast furnaces. A British startup, Novacem, is experimenting with a type of concrete that would absorb carbon dioxide, and a Canadian firm, Carbon Sense Solutions, is working on bubbling CO2 through cement to sequester carbon. An American company, Calera, is experimenting with bubbling flu gases through seawater near a California power plant to create carbonate minerals that can be used in cement production. One cement producer, Italicementi Group, is even adding titanium dioxide to concrete, which keeps the material white by acting as a catalyst under sunlight to break down the organic pollutants that darken concrete.