How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues
A chemical process called carbonation, which helps seal cracks, could help explain why many ancient Roman structures are still standing today. Researchers hope that the insights will lead to better modern-day building materials
Ancient Roman infrastructure has stood the test of time. Today, you can walk through Italy and see concrete buildings, roads and aqueducts that have survived for about two millennia. Modern concrete, on the other hand, usually crumbles within roughly 100 years .
Scientists have long tried to uncover the secrets of Roman concrete’s durability. For years, they assumed that its longevity was thanks to one key chemical process: the pozzolanic reaction, which occurs when volcanic ash reacts with the chemical lime and water. While that still holds, there seems to be more to the story.
It turns out that another chemical reaction, known as carbonation, might also contribute to Roman concrete’s longevity. The findings, published in the journal Science Advances on July 8, could help researchers develop more sustainable and resilient concrete materials.
For the new work, researchers traveled to the 1,900-year-old Hadrian’s Villa , a UNESCO World Heritage site that sits about 17 miles east of Rome. The sprawling estate is an architectural marvel, but one of its scientific gems are the communal toilets. They offer an unprecedented opportunity to study Roman concrete in its original state, unaltered by modern hands.
“Nobody restores a latrine,” says Paulo J. M. Monteiro , a study co-author and civil engineer at the University of California, Berkeley, to Sam Macdonald at Scientific American . “So, the material sat undisturbed for 19 centuries, quietly running an experiment no one alive could start.”