An easy solution to reduce carbon emissions and make concrete that lasts for a really long time.

“The ancient Roman Empire still makes its presence felt throughout Europe. Bathhouses, aqueducts, and seawalls built more than 2000 years ago are still standing—thanks to a special type of concrete that has proved far more durable than its modern counterpart. Now, researchers say they have figured out why Roman concrete remains so resilient: Quicklime used in the mix may have given the material self-healing properties.

The work could help engineers improve the performance of modern concrete, says Marie Jackson, a geologist who studies ancient Roman concrete at the University of Utah, but who was not involved with the research.

The Romans were not the first to invent concrete, but they were the first to employ it on a mass scale. By 200 B.C.E., concrete was used in the majority of their construction projects. Roman concrete consisted of a mixture of a white powder known as slaked lime, small particles and rock fragments called tephra ejected by volcanic eruptions, and water.”

 

“When the team created small cracks in the concrete—as would happen as the material aged—and then added water (as would happen with rainwater in the real world), the lime lumps dissolved and recrystallized, effectively filling in the cracks and keeping the concrete strong, the researchers report today in Science Advances. “This has an incredible impact,” Masic says.

Modern concrete typically doesn’t heal cracks larger than 0.2 or 0.3 millimeters across. The team’s Roman-inspired concrete, in contrast, healed cracks up to 0.6 millimeters across.

Masic hopes the work will inspire today’s engineers to improve their own concrete, perhaps with quicklime or a related compound.”