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Green Cement

  • Posted by Mitchell Flexo on December 16, 2010 in Science/Tech
  • Cement production accounts for five percent of global CO2 emissions, which is double the emissions from all airline traffic. That spells a massive greenhouse gas problem, just so society can continue to build and expand its infrastructures. But there has to be another way, right?

    Cement is the glue that holds concrete together. Concrete is so ubiquitous as to be nearly invisible. Producing the substance requires heating a kiln to 2,550 degrees F to break down calcium carbonate into alite. These insanely high temperatures are often reached by burning coal, which is a heavy polluter. To make matters worse, the byproduct of turning calcium carbonate into calcium oxide releases even more CO2. In other words, its a double whammy.

    That's where German tech wizardry enters the picture. Chemists at Karlsruhe Institute of Technology have created an imitation cement called Celitement that is much easier to make than standard Portland cement, thereby reducing emissions during production, and also greatly reducing the amount of CO2 produced as a byproduct. Making Celitement only requires temperatures of around 570 degrees F, or one-fifth the temperature of normal cement. And by changing the chemistry of the process, CO2 byproduct is reduced substantially as well.

    So why isn't everyone using Celitement? Well it is more expensive up front. But it can be used in normal concrete machinery, and is proving to be much more durable than standard concrete, so it pays for itself in the long run. Investors like what they see, and a pilot plant is scheduled to open in 2011. If things go well, this new technology could put a big dent in the construction industry's contribution to greenhouse gas pollution, and that's something we need sooner than later.

    (via National Geographic)

    Photo: A factory in southwest China's Sichuan province for making cement, among the most carbon-intensive industrial processes. (Evens Lee, ColorChinaPhoto/AP)





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