The Romans started making concrete more than 2,000 years ago, but it wasn’t quite like today’s concrete. They had a different formula, which resulted in a substance that was not as strong as the modern product. Yet structures like the Pantheon and the Colosseum have survived for centuries, often with little to no maintenance. Geologists, archaeologists and engineers are studying the properties of ancient Roman concrete to solve the mystery of its longevity.
“Roman concrete is … considerably weaker than modern concretes. It’s approximately ten times weaker,” says Renato Perucchio, a mechanical engineer at the University of Rochester in New York. “What this material is assumed to have is phenomenal resistance over time.”
That resistance, or durability against the elements, may be due to one of the concrete’s key ingredients: volcanic ash. Read more.