It's no secret that the Romans were better at producing concrete than we are today. Modern concrete begins to deteriorate after 50 years or so of facing the elements, whereas structures engineered in ancient Rome have proved far more enduring. Now scientists have finally pinpointed just why that is, and their findings could pave the way for stronger concrete to be formulated for today's applications — a blend that would also be less harmful to the environment.
To achieve their ultra-strong concrete, which puts our modern take (referred to as Portland concrete) to shame, Romans mixed lime and volcanic rock. "For underwater structures, lime and volcanic ash were mixed to form mortar, and this mortar and volcanic tuff were packed into wooden forms," reads a press release from the international coalition of scientists. "The seawater instantly triggered a hot chemical reaction. The lime was hydrated — incorporating water molecules into its structure — and reacted with the ash to cement the whole mixture together."
Even more impressive, the Romans released far less carbon into the air while creating this long-lasting concrete. Today, production of Portland cement accounts for seven percent of damaging carbon dioxide emissions annually. The ancient concrete blend is unlikely to become the de facto production method, however. As Futurity points out, it takes longer to harden compared with modern blends. But for scenarios where endurance is most vital, there's plenty we can learn from the "incomparable" Roman concrete.