Limestone Products
What is cement made of?
Every building you have been inside began as rock.
Dr. Lime Explains
Mostly limestone.
Limestone and clay are ground together and fed into a kiln. Inside, the mix is heated to around 1,450 degrees. The limestone breaks down, reacts with the clay, and comes out as hard grey nodules called clinker.
The clinker is ground to a powder, a little gypsum is added, and that is cement.
Roughly four fifths of the raw mix is limestone.
Worth knowing
The first step is the same reaction that makes quicklime. The limestone gives up its carbon dioxide. Cement takes it much further and much hotter, until the calcium and the clay fuse into something new.
Source: Global Cement and Concrete Association.
