Gathering "concrete" evidence

MIT News - HTML (David Chandler)
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Even though they are among the best-known structures on Earth, the pyramids of Egypt may still hold surprises. This spring, an MIT class is testing a controversial theory that some of the giant blocks that make up the great pyramids of Giza may have been cast in place from concrete, rather than quarried and moved into position.

In order to help identify blocks that were cast rather than quarried, students in the class, Materials in Human Experience (class 3.094), are assembling a small pyramid using a combination of both kinds of material. They will then use techniques such as microscopic imagery and chemical analysis to look for signs that might provide ways of telling the difference on samples from the Great Pyramid itself.

While many people think of concrete as a recent material, in fact the Romans used a version made from volcanic ash and lime extensively for most of their famous buildings, including the Pantheon. But although the idea that the Egyptians may have used a kind of concrete in building the pyramids was first suggested in the 1930s, with a specific material that could have been used proposed in 1988, so far there has been no proof and the idea has remained mired in controversy.

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