Roman concrete, also known as Opus Caementicium, was a revolutionary building material that was used extensively by the ancient Romans in their architectural constructions. It is a mixture of volcanic ash, lime, and small stones that was first developed in the third century BC and used in many of the magnificent structures that are still standing today, such as the Pantheon and the Colosseum. Roman concrete was a major breakthrough in building technology and helped to create some of the most impressive structures of the ancient world. Modern concrete does not have the longevity of ancient Roman concrete and much research has been done into this. In Britain, Roman buildings used wood, stone, turf and mixes of local materials.
The use of Roman concrete was widespread throughout the Roman Empire. Making the concrete involved mixing volcanic ash, called pozzolana, with lime and water to create a paste. Small stones, or aggregate, were then added to the mixture to give it strength and durability. The pozzolana used in Roman concrete was found in many areas of Italy, such as Pozzuoli, near Naples, which is where the material gets its name.
The use of volcanic ash in Roman concrete was crucial because it acted as a binding agent that allowed the concrete to harden and set over time. This made the concrete incredibly strong and durable, which was important for the construction of large structures that needed to withstand the test of time. The use of small stones also helped to reinforce the concrete and prevent cracking.
One of the most impressive structures built using Roman concrete is the Pantheon, located in Rome. The dome of the Pantheon, which measures 142 feet in diameter, is made of Roman concrete and is still the largest unreinforced concrete dome in the world. The concrete used in the dome of the Pantheon was so strong that it has withstood earthquakes and other natural disasters for over 2,000 years.
The Colosseum is another example of the incredible durability of Roman concrete. The Colosseum is made of a combination of brick and concrete, with the concrete used in the arches and vaults that support the structure. Despite being over 2,000 years old and having suffered damage from earthquakes and other disasters, the Colosseum still stands today as a testament to the strength of Roman concrete.
In addition to its strength and durability, Roman concrete was also relatively inexpensive to produce. The use of local materials, such as pozzolana, made the concrete easily accessible and affordable. This allowed the Romans to construct large-scale public works, such as aqueducts and roads, that helped to shape their empire.
Roman concrete was a major technological advancement in building materials that allowed the ancient Romans to construct some of the most impressive structures of the ancient world. Its strength, durability, and affordability made it an ideal choice for large-scale constructions that needed to withstand the test of time. The use of Roman concrete is a testament to the ingenuity of ancient engineers and the enduring legacy of the Roman Empire.
- The Roman Pantheon: The Triumph of Concrete Research by the late David Moore, P.E.
- Why Roman concrete still stands strong while modern version decays (2014, Guardian)
- Secret to durability of Roman concrete that has stood test of time for over 2,000 years finally unearthed (2023, Scotsman)
- Notes on Building-Construction in Roman Britain (The Journal of Roman Studies, Vol. 22, Part 1: Papers Dedicated to Sir George Macdonald K.C.B. (1932), pp. 117-134 (22 pages))
- Roman Building-Materials in South-East England (Britannia, Vol. 2 (1971), pp. 166-195 (33 pages))