Cement is made from limestone and other ingredients in a high temperature kiln process above 1300°C. One by product of the cement preparation is a large amount of carbon dioxide, a greenhouse gas which is not friendly to the environment when in excess amounts.
Scientists at Stanford University, led by Brent Constantz, have found an alternative to traditional cement production. They study coral which forms the largest biologically formed structures in the world.
convert CO2 gas from powerplants to concret
Australia’s Great Barrier Reef, for example, covers more than 160000 square kilometers. Coral consists of calcium carbonate, CaCO3, the same chemical compound as limestone. Biomineralization is the process by which the coral organisms build their exoskeleton homes from seawater.
The Stanford researchers have learned to duplicate the chemical ability of the coral. Carbon dioxide gas is captured, from a power plant for example, and then is dissolved either in sea water or in brine from deep wells. The result is carbonated water which is then mixed with calcium to precipitate calcium carbonate as a powder. When dried, this material is found to function well in place of the previous high temperature cement process. And in the bargain, large amounts of carbon dioxide gas are soaked up or sequestered instead of being released to the atmosphere.
A company called Calera is testing the new user-friendly approach to cement production.
Stanford University (Brent Constantz)
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