Ingredient in Roman concrete Crossword Clue

 The ingredient in Roman concrete that is credited with its long-lasting durability is volcanic ash.

When mixed with lime and water, volcanic ash reacts to form a mineral called tobermorite. Tobermorite is a very strong and durable material, and it is what gives Roman concrete its superior strength and longevity.

In addition to volcanic ash, Roman concrete was also made with a variety of other materials, including lime, sand, and water. The exact composition of Roman concrete varied depending on the region where it was made, but the use of volcanic ash was a key ingredient in all Roman concrete.

Roman concrete was used to build a wide variety of structures, including roads, bridges, aqueducts, and temples. Many of these structures are still standing today, over 2,000 years after they were built. This is a testament to the durability and strength of Roman concrete.

In recent years, scientists have been studying Roman concrete to try to understand its secrets. They have discovered that the volcanic ash in Roman concrete reacts with seawater over time to form a even stronger and more durable material. This is why many Roman concrete structures that are exposed to seawater are even better preserved than those that are not.

Scientists are now trying to develop new types of concrete that incorporate the same principles as Roman concrete. These new concretes could be used to build structures that are more durable and sustainable than traditional concrete structures.