Super concrete in the U.S. military, Iran ... and the pyramids?

The story of geopolymers is worthy of a Dan Brown novel, with an unlikely cast including a maverick French scientist, a secretive caste of ancient stone masons and the U.S. Air Force Research Laboratory. Along the way, the mystery of the pyramids gets solved, but it might just end with American bombs bouncing off impervious bunkers.

Geopolymers are technically described as synthetic aluminosilicate materials, but they might be more easily described as super-cements or ceramics that do not need firing. A mug made of Geopolymer will bounce off a concrete floor.

The technology of cement-making has been repeatedly lost and rediscovered. The Romans knew how to mix crushed rock (”caementitium”), with burnt lime and water to make a versatile building material. The Pantheon in Rome boasts the world's largest unreinforced concrete dome, still just as strong after 2,000 years. But cement was unknown in medieval times, with lime mortar serving as a poor substitute.

However, by the 1950s, it was obvious that much modern cement is not as durable as the ancient variety, and many buildings succumbed to concrete cancer caused by water penetration and chemical action. Ukrainian scientist Victor Glukhovsky looked into why the ancient cement recipes were so much more durable than modern ones and found that adding alkaline activators gave a greatly superior product. His work inspired Joseph Davidovits, a French chemical engineer, to discover the chemistry behind geopolymers and how it can be manipulated.

Professor Davidovits was awarded the French Ordre National du Mérite, and is President of the Geopolymer Institute. His most remarkable claim is that the pyramids were built using re-agglomerated stone, a sort of geopolymer limestone concrete, rather than blocks of natural stone. This would explain many of the mysteries of pyramid construction. Handling barrels of liquid concrete and casting in place would be much easier than moving giant blocks of stone. Remarkably, recent X-ray and microscopic study of samples has supported the theory that the pyramids are made of artificial stone.

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