Researchers investigate ancient Roman concrete to make durable, lower carbon mortar

Researchers have turned to an ancient Roman concrete recipe to develop more durable concrete that lasts for centuries and can potentially reduce the carbon impact of the built environment.

To construct architectural marvels that still stand today, ancient Romans combined lime, volcanic ash, and aggregates with water to create concrete. A key difference from how modern concrete is processed is temperature.

Today, we use cold mixing—a process conducted under ambient temperatures—but Romans used hot mixing, heating the mixture to 180 degrees Fahrenheit. This resulted in a key change in the lime that provides concrete with the ability to self-heal.

“Due to hot mixing and creation of these tiny granules of lime due to hot mixing, eventually you create a mechanism that just naturally goes and fills the crack with the material and prevents water to flow and propagation of the crack,” an MIT professor told National Public Radio. If modern manufacturers can emulate the ancient method, the result would be longer lasting structures that in the long run will result in using less concrete which will correspond to less emissions.

Listen to the NPR Weekend Edition segment: