Emily Chan
It is a wonder as to how some of the ancient architectural structures of Rome still remain standing today.
Modern infrastructure is constantly at risk of falling apart after a few decades, or even a few years. But, the aqueducts and buildings that the Romans created have endured the test of time and continue to be stable constructions at historical sites that tourists visit every year.
Last year, researchers from the Massachusetts Institute of Technology (MIT), Harvard University, and laboratories in Switzerland and Italy unlocked the secret to the durability of the 2,000-year-old structures. Self-healing concrete is the reason they are so long-lasting.
The study shows that a special ingredient called “lime clasts” is what made ancient Roman concrete so strong.
Previously, scientists believed that volcanic ash from Pozzuoli on the Bay of Naples was what contributed to the toughness of the concrete. The ash was shipped across the Roman Empire to be used for construction.
However, in the most recent study, the researchers looked at lime clasts for answers. Lime clasts are small, white chunks that were mixed into the concrete.
In the past, they were thought to be the result of careless practices or low-quality materials. They are also not included in modern concrete formulations.
Overall, they didn’t seem to serve any purpose. But, it turns out that lime clasts are what gives the ancient concrete self-healing abilities.
“The idea that the presence of these lime clasts was simply attributed to low quality control always bothered me,” said Admir Masic, a professor of civil and environmental engineering at MIT.
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