Roman concrete

Roman concrete is a kind of cement that the ancient Romans used to build their big buildings, like aqueducts and bridges. It is special because it is made from things that can be found in nature, like volcanic ash, seawater, and limestone.

First, they would mix together the volcanic ash and lime in a pit with a little bit of water. Then they added pieces of rock, called aggregate, like chunks of limestone or brick. The workers would mix and pour the wet mixture into wooden frames shaped like walls, columns, or whatever they needed.

Then, they would wait for the cement to dry and harden. As it dried, the mixture started to chemically react and bind together all the ingredients, creating a very strong and durable material.

Roman concrete was so strong that even after thousands of years, many of their buildings still stand today. It is amazing to think that the mixture was made from materials found in nature and that, even without modern technology, the Romans were able to create such massive and enduring structures.