Roman concrete continues to amaze with its durability and ability to self-heal over time.
A MIT study revealed the composition and technique that made it possible for many structures to remain standing after centuries of wear.
What makes Roman concrete so resilient?
The key lies in the combination of pozzolana (volcanic ash), lime, and water. This type of mixture caused a chemical reaction that produced an extremely durable material.
The ash came from the Pozzuoli area, near Naples, and its use allowed the concrete to harden even underwater, which was crucial for ports and aqueducts.
The "hot mixing" technique
The Romans not only chose good materials, they also applied a revolutionary technique for the time: they mixed quicklime with pozzolana and water at high temperatures.
This method, in addition to accelerating the setting, caused lime clasts, small white particles that proved to be key in the self-healing process.
