2,000 years ago, ancient Roman engineers were building structures that have withstood the test of time remarkably well, many of which remain standing today. At the heart of their success lies a mystery: what were the secrets of ancient Roman concrete that made these buildings so durable?
Now, MIT researchers are drawing from this curiously durable technology of the ancient world to help them develop modern building materials that can last longer, and potentially even reduce the carbon footprint of modern construction—all while managing to self-repair itself by healing small cracks.
The mystery of Roman concrete became a fascination for MIT Associate Professor Admir Masic, who has spent many years now investigating the chemistry and other properties of this durable ancient technology. Based on his research, the material’s longevity isn’t just a product of the ingredients used by its ancient creators: the secret of Roman concrete also has to do with its manufacturing process.
This, according to Masic, seems to be at the heart of the material’s unusual ability to repair itself after cracks begin to form.
In 2023, Masic and his colleagues began looking at samples of lime that were very rich in calcium, which researchers call “lime clasts.” These clasts are ubiquitous throughout concrete found in ancient Roman constructions, although they were long discounted as being the byproducts of imperfections in the mixing process.
However, closer inspection revealed something remarkable about these lime clasts: as cracks form in the concrete, water can gradually enter the material, allowing calcium within the lime casts to dissolve and then recrystallize, effectively sealing the newly formed openings.
Now, that discovery is propelling the development of modern concrete that incorporates calcium-rich lime clasts, thanks to a partnership between Masic and Italian entrepreneur Paolo Sabatini, who joined forces to develop a commercial version now being produced by Dmat, a company they co-founded in 2021.
Part of the strength of Dmat’s approach is the fact that they have developed additives that can be added to existing kinds of concrete and mortar, rather than requiring builders to acquire new and unfamiliar materials.
“We can now offer an extremely competitively priced, self-healing product that is easy to implement and available worldwide,” Masic recently told MIT News.
“What’s exciting to me is that this material could become the industry standard without requiring companies to change how they operate,” he added.
Beyond its ability to strengthen the durability of concrete, Dmat’s new technology can also reduce carbon dioxide emissions by up to 40 percent compared to those in traditional concrete. Presently, the new material is already being used in several infrastructure projects in parts of Europe, with eventual plans for expansion into the United States and other countries.
Widespread implementation and scalability like this is important, according to Masic and his colleagues, since large volumes of concrete are produced throughout the world, the production of which accounts for as much as 8% of global carbon dioxide emissions.
Extending the life of structures while simultaneously reducing the emissions associated with their construction would therefore hold significant environmental benefits.
“At Dmat, we like to view concrete as an ecosystem,” Sabatini recently said in a statement. Successfully introducing a new material, he argues, requires considering not merely its chemistry, but cost, transportation, certification, and compatibility with established construction practices.
Notably, Dmat’s approach differs from other examples of modern experimental self-healing concretes, which generally rely on bacteria or polymers. Instead, by placing the focus on ancient techniques used by Roman engineers that long remained overlooked and misunderstood, Masic and his colleagues have developed an innovative new technology with roots that go back almost two millennia.
“There’s something profound about how ancient builders, without our modern chemistry, engineered self-healing material that still stands today,” Masic notes.
“My group research and work with Dmat is to make the modern built environment better by applying the best lessons from the past to today’s challenges,” he adds.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.
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