Ancient Roman buildings, bridges and aqueducts have survived for thousands of years, and scientists have long wondered why their concrete has proved so durable.
Now, lessons from Roman construction are being used to develop modern concrete that can repair small cracks on its own.
MIT Associate Professor Admir Masic has spent years studying the chemistry of ancient Roman concrete. In 2021, he co-founded a company called DMAT to turn those discoveries into practical materials for today’s construction industry.
The company says its technology can extend the lifespan of concrete structures by about 50% while reducing carbon dioxide emissions to as little as 40% of those associated with traditional concrete.
DMAT’s materials are already being used in Europe for projects including underground water tanks, road barriers, pavement and motorway repairs in Italy and Switzerland. The company is also preparing to expand into the United States.
The technology grew out of research into why Roman concrete can remain strong for extraordinarily long periods.
When scientists examined ancient concrete, they found small white pieces of calcium-rich material known as lime clasts. These were once thought to be signs of poor mixing or low-quality construction. Masic and his colleagues discovered that they may actually be one of the secrets behind the concrete’s durability.
In a 2023 study, the researchers showed that when cracks form and water enters Roman concrete, calcium from these small pieces can dissolve and move into the damaged area. It then recrystallizes, helping fill and seal the crack before it becomes a larger structural problem.
In effect, the concrete has a built-in repair system.
The researchers recreated this ancient approach in modern concrete by deliberately including calcium-rich lime particles in the mixture. After extensive testing, they found that the method could improve the strength and durability of different types of concrete.
Those discoveries became the foundation for DMAT.
Rather than asking construction companies to completely change how they make concrete, the company has developed additives that can be incorporated into existing concrete and mortar mixtures. It also produces ready-to-use mortars for repairing structures.
This could make the technology easier to adopt. Other approaches to self-healing concrete have used bacteria or special polymers, which can be expensive or unfamiliar to construction companies. DMAT instead focuses on materials and processes that fit more easily into existing industry practices.
Making concrete last longer could have an important environmental benefit.
Concrete is the world’s most widely produced construction material, and its production is responsible for an estimated 5% to 8% of global carbon dioxide emissions. Structures that last longer need fewer repairs and replacements, potentially reducing the amount of new concrete required over time.
The researchers believe the technology shows how studying the past can help solve modern engineering problems.
Roman builders didn’t have today’s scientific knowledge or advanced manufacturing equipment. Yet some of the structures they created have survived for nearly two millennia.
By understanding the chemistry behind that remarkable durability, scientists hope to give modern roads, bridges and buildings some of the same ability to stand the test of time.
