Old toilets recycled into new "green" cement
By Ben Coxworth
April 3, 2014
An international team of researchers has discovered a potential new use for discarded toilets, along with other ceramic waste such as basins, stoneware and bricks. It turns out that they can be made into a more eco-friendly form of cement.
To make the cement, ceramic waste is ground up, then mixed with an activator solution and water. The resulting mixture is then poured into a mold, and subjected to a high-temperature hardening process.
In tests conducted with items made from red clay brick waste, the cement was actually stronger than types that are currently in common use. The strength of cement made with other forms of ceramic waste is still being evaluated.
Sodium hydroxide or sodium silicate have been used as the activators so far, although the researchers are reportedly getting promising results using rice husk ash. If it could be used, then the result would be a cement made entirely from reclaimed waste materials. Not only would this keep discarded ceramics and rice husks out of the waste stream, but it could also provide a source of revenue for groups providing the material.
Additionally, it could be used as an alternative to Portland cement, which is the world's most widely used form of cement. Production of Portland cement releases large amounts of carbon dioxide, and as such the material is considered a major contributor to global warming.
The research is being conducted by 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.
Source: Asociación RUVID (Spanish)