Cement is good for hiding whatever lies underneath. Old mob movies bring to mind laughing goons pouring the wet grey slurry over an unlucky victim, while rotting garbage is buried underground and sometimes paved over. Cement is not seen in a positive light, especially not when it comes to the environment.
The innovative mind of John Harrison thought up the idea of using waste (typically industrial and carbon) in cement, rather than simply producing cement to pave around it. Harrison, managing director at Australia’s TecEco, founded a company with the goal of producing a building material with a positive environmental impact.
Now a brand name, eco-cement is a limestone base (like all cements) mixed with magnesium oxide which is heated in a kiln and turned to powder. This powder will eventually be added to gravel and water to form cement. The magnesium oxide in eco-cement lowers the kiln temperature to about half of that required by the most common cement used in the world: Portland cement. This substantially lowers the amount of energy needed to make eco-cement. Not only that, but eco-cement is more porous than other cements and the unique magnesium oxide/cement mix actually absorbs carbon dioxide from the environment (only for about a year, though)!
In TecEco’s question and answers forum, the company was asked how they came about the idea of “eco-cement”. The answer was that “the idea of using carbon and wastes in building materials came from nature. During earth’s geological history large tonnages of carbon were put away as limestone and coal by the activity of plants and animals building homes such as the shells of shellfish and wood in trees. These same plants and animals wasted nothing as food and nutrients moved around and the waste from one was the food or home of another. John concluded that the answer to greenhouse gas and waste was to use them both in building materials.”
True to this ideal, eco-cement can be completely recycled when a structure is no longer required and reformed again.
As the founder and current chair of the Association for the Advancement of Sustainable Materials in Construction (AASMIC), Harrison is obviously devoted to green building materials. Online he writes; “I believe that our approach to sustainability must be holistic. i.e. a bit like dieting. The pain of either dieting or exercise is less if one does both. So it is with progress towards sustainability – reductions in energy usage as well as massive sequestration, less rubbish (e.g. packaging) as well as new uses for it are required. Improvements in energy use efficiency have been relatively popular as they save money. The harder task I am addressing is how to get the CO2 out of the air.”
The ideas presented by TecEco are catching on and other companies like Zeobond, scheduled to start operations in February, are adopting similar philosophies.