The magic of Roman concrete

This magical material becomes harder and stronger over time.

KIM SEUNG-JUNGThe author is a professor of archaeology at the University of Toronto. As I teach about the Pantheon this semester, I couldn’t help but admire ancient Roman architectural technology again. Ancient Greek accomplishments are often credited as the foundation of Western arts and culture. The Greek sculptures reached the epitome of beauty and became the prototype for Michelangelo’s David, and Western philosophy was established based on ideological compositions of Plato and Aristotle. Even the political structure of democracy originates from ancient Greece.

However, Roman architectural arts are completely different from those of Greece. No matter how mathematically accurate the Parthenon may be, it still hasn’t transcended the columns and lintels of dolmen. In contrast, structures from the Roman Empire are made of massive and complicated buildings using arches, with the invention of concrete.

The Colosseum, which can accommodate 80,000 spectators, is ten times the size of a common Greek theater. The aqueducts, the signature construction of the Roman Empire, reflects exact slopes of roads in tens of kilometers. Large-scale thermae, or public baths, were built using water drawn from multiple sources.

What concrete made all these triumphs possible and preserved the Pantheon in the earthquake-prone region for 2000 years? It is already well known that various clever earthquake-resistant designs were applied at that time. Recently, a MIT research team discovered a surprising fact. Roman concrete made by combining volcanic ashes from Naples with quicklime at a high temperature can self-heal cracks.

This magical material becomes harder and stronger over time. The Portland cement used today collapses as time passes. Science and technology are not a cure-all since improving partial sophistication may cause the whole thing to collapse. According to the records of the history of science, it is foolish to only adhere to the concept of progress.