Paul Statt Communications

When you take on the sole survivor of the Seven Wonders of the Ancient World, the modern world takes notice. Michel Barsoum never sought fame as an Egyptologist, and whenever the Drexel material scientist tells the story of how he helped reveal the ancient secret of the construction of the pyramids, he starts by insisting, “This is not my day job.”

Barsoum helped prove the theory that the pyramids were partially constructed of concrete. Not content with that intriguing possibility, Barsoum charged ahead to investigate how the ancient Egyptians could have made concrete, millennia before its “invention” by the Romans. “How energy intensive or complicated can a 4,500 year old technology really be?” Barsoum asks. The answer, he reports, is that “it is not very complex or costly” and thus, may be useful even today.

Barsoum and his team have invented—or re-invented—an inexpensive, environmentally sustainable and widely available building material: the kind of concrete he thinks the pyramid builders used. What makes Barsoum most proud is the potential practical application of the “geopolymer” that he and his team have reconstructed. A “chance” discovery about the ancient world, made by an engaged engineer, has the potential to help solve some of the environmental and economic problems that vex the world today.

In 2001 Barsoum took a cold call from a friend of a retired colleague, who wanted to know how much Barsoum knew about “the mysteries of the Great Pyramids of Giza.” Barsoum was born in Egypt and has a bachelor’s degree in materials engineering from the American University in Cairo, but didn’t know much about the construction of the famous monuments.

Conventional wisdom offered a familiar image: thousands of slaves hauling carved limestone blocks up ramps hundreds of meters long. But in 1982 a French researcher had suggested that the stones of the pyramids were actually made of a very early form of concrete created using a mixture of limestone, clay, lime and water.

“It was at this point in the conversation that I burst out laughing,” recalls Barsoum. If the pyramids were indeed cast in concrete, not stacked blocks of stone, he says, it could be proved with just a few hours of modern electron microscopy of the structure of the materials.

It hadn’t been tried. Barsoum, who says today that “stubbornness” is one of the important qualities a good researcher needs, decided to try it, and “What started as a two-hour project turned into a five-year odyssey with one of my graduate students, Adrish Ganguly, and a colleague in France.”

Barsoum and the team analyzed the mineralogy of parts of the Khufu pyramid and found mineral ratios unknown in naturally occurring limestone sources. From the geochemical mix of lime, diatomaceous earth and limestone aggregate, they concluded, “the simplest explanation” would be that it was cast concrete. Construction with limestone concrete could help explain how the Egyptians were able to complete such massive monuments so long ago. They used concrete blocks, Barsoum said, on the outer and inner casings and probably on the upper levels, where it would have been difficult to hoist carved stone.

“The sophistication and endurance of this ancient concrete technology is simply astounding,” Dr. Barsoum wrote in a report in the December 2006 issue of The Journal of the American Ceramic Society. John Noble Wilford wrote in The New York Times that “This would be the earliest known application of concrete technology, some 2,500 years before the Romans started using it widely in harbors, amphitheaters and other architecture.”

It isn’t its aura of romantic adventure and ancient mystery that excites Barsoum about this research. It’s much more practical. After all, he says, “At the end of the day, we may be wrong about the pyramids. Nature is very resourceful. What I know for sure is that we are now making this geopolymer. And the ingredients are simply dirt, dirt, dirt and water.”

When he mentions “dirt, dirt, dirt and water” Barsoum’s eyes light up. The import of such a simple recipe for such an extraordinary material also is firing the imagination of his engineering students from freshmen to seniors. Barsoum says, “This ancient variety of concrete can be made just about anywhere in the world from readily available materials, at a very low cost, and without producing the pollution of traditional methods.”

It’s easy to make. Barsoum’s undergraduates work with it all the time: he keeps a cast representation of a cat in his office, and it’s beautiful: as smooth and shiny as marble. The possibilities for housing, transportation and infrastructure, in places that where energy and money are limited, are limitless.

“The basic raw materials used for this early form of concrete–limestone, lime and diatomaceous earth—can be found just about anywhere.” Barsoum quickly adds that this simple construction method would be cost effective, long lasting, and much more environmentally friendly than the current building material of choice. It’s estimated that the manufacture of Portland cement puts 6 billion tons of CO₂ annually into the atmosphere. The ancient Egyptian method is practically pollution-free.

“Ironically it turns out the study of these four thousand year old rocks,” Barsoum says, “isn’t about the past, it’s about the future of the planet.”

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Barsoum, Distinguished Professor in the Department of Materials Science and Engineering, received the Drexel University Research/Scholarship Award in 2007 for the discovery of the kinking nonelastic deformation, a fully reversible deformation mode which is observed in a wide range of materials including geological materials, ceramic materials, graphite and hexagonal metals. This discovery is expected to have major ramifications for the development of new high damping, high strength and high toughness structural materials.