Old toilets, other ceramic waste can be made into "greener" cement
Recycling old concrete into new cement is nothing new, but throwing in old toilets and bath tubs? That one we haven't heard before. According to an international team of researchers working on creating cleaner cement, those ceramic castaways, as well as bricks, can be used to make a cement that's just as strong as traditional cement, but through a process that's much less dirty.
For the new cement, ceramic waste is ground up and mixed with an activator solution -- in this case sodium hydroxide, sodium silicate or even potentially rice husk ash -- and water. The mix is poured into a mold and baked under high temperatures. Tests on a mixture made with red clay brick show it to be actually stronger than common types of cement.
According to the researchers, who hail from Spain's Universitat Politècnica de València and Universitat Jaume I de Castellón, Imperial College of London, and the Universidade Estadual Paulista of Sao Paulo in Brazil, if these waste ceramics are used with the rice husk ash activator, then the resulting mix is a cement made completely from waste materials, which means waste streams are kept out of landfills and groups providing those materials could have a new way to produce revenue.