found this on Treehugger.com: Eco-Cement! sustainable cement products made by TecEco. according to the folks at TecEco, the secret formula (and addition of magnesium oxide) means their eco-cement & bricks take less energy to produce. and, it reduces landfill by turning “virtually any solid waste†into concrete. but there’s more: for up to a year, eco-Cement absorbs carbon dioxide from the air. all around, eco-cement is easier to recycle, uses less energy, reduced CO2, and reduces landfill. i hope this process really takes off!