Sunday, December 10, 2006

Lost Concrete Secrets

The discovery of an ancient secret for making concrete could aid the developing world and reduce Green House Gases.

Riddle Of The Great Pyramids Of Giza: Professor Finds Some Building Blocks Were Concrete

In partially solving a mystery that has baffled archeologists for centuries, a Drexel University professor has determined that the Great Pyramids of Giza were constructed with a combination of not only carved stones but the first blocks of limestone-based concrete cast by any civilization.

Michel Barsoum, professor of materials engineering, shows in a peer-reviewed paper to be published Dec. 1 in the Journal of the American Ceramic Society how the Egyptian builders of the nearly 5,000-year-old pyramids were exceptional civil and architectural engineers as well as superb chemists and material scientists. His conclusions could lead to a seismic shift in the kind of concrete used in construction and provide developing nations a way to build structures utilizing inexpensive and easily accessible materials.

Barsoum, whose interest in the pyramids and geopolymers was piqued five years ago when he heard theories about the construction of the pyramids, says that to construct them with only cast stone builders would have needed an unattainable amount of wood and fuel to heat lime to 900 degrees Celsius.

The type of concrete pyramid builders used could reduce pollution and outlast Portland cement, the most common type of modern cement. Portland cement injects a large amount of the world's carbon dioxide into the atmosphere and has a lifespan of about 150 years. If widely used, a geopolymer such as the one used in the construction of the pyramids can reduce that amount of pollution by 90 percent and last much longer. The raw materials used to produce the concrete used in the pyramids -- lime, limestone and diatomaceous earth -- can be found worldwide and is affordable enough to be an important construction material for developing countries, Barsoum said.



Ancient World



Ancient civilizations

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