What are the Great Pyramids really made of?

One hundred thousand slaves tug multi-ton blocks across the desert. A complicated series of pulleys lifts each hand-cut stone into the perfect place. This is history's image of ancient Egyptian pyramid construction.

What if the Egyptians were using an easier, more efficient method? Recent theories and scientific evidence suggest that people assembled cement blocks on site to construct the exterior of the pyramids. Here's why everything you thought you knew about how we built the Great Pyramids is probably wrong.

Top image: via sculpies/Shutterstock.

What are the Great Pyramids really made of?

X-raying the Pyramids

Materials scientist Joseph Davidovits suggests a more realistic way to look at how the pyramids were built. Unconvinced of Egyptian abilities to construct and move large blocks to create the pyramids, Davidovits posits that Eqyptians molded blocks from limestone and vegetable matter available nearby. These blocks, built on site, are then used to build the pyramids. Existing only as a hypothesis, Davidovits later supported his idea using X-Ray Diffraction data, a technique common in chemistry and material science.

Analysis of Casing Stones

Scientific inquiries revolve around the "casing stones" used on the pyramids – the outer layer of polished stone. In the paper X-Ray Analysis and X-Ray Diffraction of Casing Stones from the Pyramids of Egypt, and the Limestone of the Associated Quarries, Davidovits looks at stones from six different sites.

Through analysis, the casing stones at the sites contain air bubbles. This is stark contrast to rocks from the quarries, quarries the casing stones are typically associated with, with the quarry rock containing no bubbles. The presence of air bubbles in the casing stones supports the "cement" theory. Davidovits also wrote a journal article describing how a cement-like substance could be made using local fauna and tools like antlers and bone.

What are the Great Pyramids really made of?

Evidence for Cement Technology

Pliny the Elder, a historian and Naval Commander in Rome during the first century C.E wrote Naturalis Historia , an early attempt to construct an encyclopedia. Pliny the Elder makes several references to Egyptian created "formed" stones, particularly in the creation of vases:

In this way occurs a multitude of heaps (of minerals) which can be transformed into real rocks. They Egyptians make vases in this way...

Granted, Pliny wrote thousands of years after the creation of the pyramids, but this notation provides evidence of a cement-like technology used by the Egyptians two thousand years ago.

Recent scientific analysis

Davidovits' work is often discounted due to the aspect that he is the originator of the cement pyramids theory. Other scientists, however, are using modern techniques to examine the stones. In the 2011 paper, Were the casing stones of Senefru's Bent Pyramid in Dahshour cast or carved? Multinuclear NMR evidence, nuclear magnetic resonance experiments show the casing stones of Senefru's Bent Pyramid to be a combination of limestone grains from one quarry cemented with a calcium-silicate gel from a second quarry.

Resistance to the molded pyramid

Although multiple research groups provide evidence for cement-based casing stones, Egyptologists are rather reluctant to accept these scientific inquiries. Zahi Hawass, long time (and now former) Egyptian Minister of Antiquities calls the theory of cement-cast pyramids "plain stupid", adding in a 2006 conversation:

Of course they're not. They're made from solid blocks of quarried limestone. To suggest otherwise is idiotic and insulting.

It is rather difficult to change decades of thinking, especially in a science that often relies on subjective and visual interpretations to reach conclusions.

A more efficient way

So were the pyramids constructed with cement? It's certainly a plausible theory, and it eliminates the questions surrounding how a civilization cut and transported the massive stones from quarries. No aliens or futuristic technology needed – only locally made cement and molds. A cement cast would allow for on-site production, decrease time & personnel needs, and create a uniform shape. If Ockham's Razor applies, Davidovits' view is the winner.

Images from Shuttershock, Philip Coppens, and the British Museum. Sources linked within in the article.