Green Cement – The Next Step in Environmentally Conscious Construction
The sight of cement doesn’t usually conjure up ‘warm fuzzies’ in the hearts of environmentalists. The fact that 5 percent of the world’s carbon emissions are caused by cement production might have something to do with that lack of positive feelings. Imagine, though, what a significant environmental impact it would have if someone could ‘green’ the production process and reduce carbon emissions. As it turns out, several companies are doing just that.
There are several approaches in the works. One approach is to develop a cement production process that absorbs more carbon than it creates. Another approach is a process with zero carbon dioxide emissions.
Australian company, Calix, has applied for a patent on their process that uses superheated steam to rapidly calcine calcium magnesium particles. The residue from the calcination and oxidation processes is mixed with sand to form Semidolime, which is then mixed with water and CO2-rich power plant flue gas.
Although CO2 is produced during the new Calix process, the manufactured cement absorbs 21 kilograms of CO2 while hardening into concrete. The net CO2 emission is -7 kilograms. Cement that uses more CO2 than it generates would undoubtedly warm the hearts of environmentalists and many others.