We now know the secret to why Roman concrete lasts thousands of years

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Ancient Rome was full of master builders and engineers. The fruits of their labors can still be seen in the aqueducts they built—which still function to this day—as well as the Pantheon, a nearly 2,000-year-old building that still holds the record for the world’s largest dome of unreinforced concrete. For decades, scientists have been trying to figure out the secret to Roman concrete, and now, they may have made a major breakthrough.

This concrete, often referred to as pozzolanic concrete, is extremely durable and is the primary ingredient that gave ancient Roman structures their amazing strength. Scientists are hopeful they’ve not only figured out how to make ancient Roman concrete but also what made it such a strong building material—and what made it so much better than the concrete that most of our buildings rely on today.

For years, researchers believed the secret to Roman concrete was the mix of volcanic ash and lime that the ancient Romans used. However, a team of researchers led by MIT uncovered more about the unique technique that ancient Roman engineers used to mix the two materials together to make their concrete.

As I noted in previous coverage on concrete used in ancient Rome, the engineers back then seem to have relied on what we call lime clasts to provide additional strength and healing properties to concrete used in ancient Roman times. It’s these clasts that have always drawn a bit of bafflement from scientists, as it was always believed by many that they were simply mistakes left behind during the mixing process.

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However, everything we know about the ancient Romans raises questions about such a low-quality mistake. How could a group of people so well known for crafting quality structures have always left behind so many mistakes in their mixing process? It never made sense to researchers like Admir Masic of MIT, one of several authors of the study published in 2023 that helped unravel the secret of Roman concrete and its immense strength.

From here, the team hopes to find a way to recreate the process that the ancient Romans used as a more environmentally friendly alternative concrete to Portland concrete, the standard type of concrete used in most construction projects these days. With scientists already striving to create alternatives like hollow concrete that is 500 percent stronger, commercialized Roman concrete could be an exciting next step for the construction industry.

Josh Hawkins has been writing for over a decade, covering science, gaming, and tech culture. He also is a top-rated product reviewer with experience in extensively researched product comparisons, headphones, and gaming devices.

Whenever he isn’t busy writing about tech or gadgets, he can usually be found enjoying a new world in a video game, or tinkering with something on his computer.