The Secret to Making Concrete That Lasts 1,000 Years

This is one amazing discovery, directly affecting climate! Ivan

Scientists have uncovered the Roman recipe for self-repairing cement—which could massively reduce the carbon footprint of the material today.

Currently, concrete is second only to water as the world’s most consumed material, and making it accounts for about 7 percent of global emissions.

“Every wall made out of Roman concrete will have these inclusions,” Masic says, who in the past has looked at structures across Israel, North Africa, Italy, France, and Spain. Previously the lime clasts were thought to be a product of not mixing the concrete properly, Masic explains. But the team’s scanning revealed that the clasts were formed at extremely high temperatures, and are made from various forms of calcium carbonate. They contain a kind of calcium that Masic’s team theorized could heal cracks by reacting with water, creating a solution that recrystallizes in fissures to fill them in. That calcium, he says, could be the “missing link” explaining the material’s durability.

The question, then, was where the necessary heat came from to make those clasts. It had been thought that Roman concrete was created by combining water with a calcium compound called slaked lime. But what if the Romans used lime in a more reactive form, called quicklime, Masic wondered. When mixed with water, quicklime reacts and produces heat.

Patents have now been secured by MIT. Masic says a company will begin producing what he calls Roman-inspired concrete by year’s end. “Translating this knowledge of the ancient world into modern applications, I think that’s the next step,” he says. “These cracks are healed in two to three weeks using ingredients that are readily available and, most importantly, cheap.”

Masic’s paper is the latest in a string of investigations into Roman concrete. Last year, he published research with Marie Jackson, a researcher at the University of Utah, that examined the 70-foot-tall tomb of first-century Roman noblewoman Caecilia Metella on the Appian Way, an ancient Roman road that runs across Italy. Their investigation revealed that the particular formation of Roman concrete used in the tomb interacts with rainwater and groundwater, becoming more resilient over time.

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