The Strength of Roman concrete

Arch of Septimius Severus. Picture taken by Kevin Guo in his trip to Rome.

The key to the toughness of Roman concrete was the addition of pozzolanic ash, especially from the Bay of Naples. This kind of volcanic ash was added to concrete to be more resistant to cracks. Recent research shows that a mix of different types of lime in Roman concrete allowed it to self-repair cracks over time.

Roman concrete was used extensively around 150 B.C. and maybe even further. It can be seen in many ancient structures like bridges, reservoirs, and aqueducts. The most famous example is the Pantheon dome, the world’s largest and oldest unreinforced concrete dome.

The dome of Agrippa’s Pantheon. A picture taken by Kevin Guo.

One unique characteristic of Roman concrete was that it included larger pieces of aggregate, which meant it had to be laid rather than poured. This meant that it was suitable for various types of construction, including underwater structured.

Even today, scientists and engineers are studying Roman concrete to truly understand its incredible durability. They hope to replicate its properties using modern materials. One approach by modern engineers is to use coal fly ash, which has similar properties to pozzolanic ash. This modern version of Roman concrete could be more cost-effective and more environmentally friendly.

Work Cited

Chandler, David L. (6 January 2023). "Riddle solved: Why was Roman concrete so durable?". MIT News. Archived from the original on 21 January 2023.

Moore, David (February 1993). "The Riddle of Ancient Roman Concrete". S Dept. of the Interior, Bureau of Reclamation, Upper Colorado Region.

Mark, Robert; Hutchinson, Paul (March 1986). "On the Structure of the Roman Pantheon". The Art Bulletin. 68 (1). New York, NY: College Art Association: 24. doi:10.2307/3050861. JSTOR 3050861.

Wayman, Erin (16 November 2011). "The Secrets of Ancient Rome's Buildings". Smithsonian.com.

McGrath, Matt (4 July 2017). "Scientists explain ancient Rome's long-lasting concrete". BBC News.

Roman concrete, also known as opus caementicium, is one of the most important building materials that showcases the brilliance of Roman engineering. Like modern concrete, it is made by mixing hydraulic cement with an aggregate; however, it is incredibly durable, which allows many Roman structures to stand even today.