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 The Canopus, a pool at Hadrian's Villa in Tivoli, Italy Carole Raddato via Flickr under CC BY-SA 2.0 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.…