GabyThese buildings have survived for millennia. And that’s because ingenious ancient Roman engineers knew the recipe for durable concrete.
So there’s no need to be surprised that such colossal structures, like Colosseum The Pantheon (the building with the largest unreinforced dome in the world) has stood for over 2000 years. Even structures built in earthquake zones and other challenging construction sites have survived to this day.
Researchers from the USA, Italy, and Switzerland have found that Roman concrete is more durable than its modern counterpart, which often deteriorates within a few decades. The team of scientists discovered a mysterious ingredient that made the ancient Romans’ building material so strong.
Scientists analyzed samples of two-thousand-year-old concrete taken from archaeological excavations in the commune of Privernum (central Italy). In terms of composition, these pieces are identical to other concrete samples found throughout the Roman Empire.
As researchers have established,whiteThe lime fragments in the concrete gave it an amazing quality.the ability to heal cracks that formwere being treatedover time.Previously, these inclusions were considered the result of careless mixing or the use of low-quality raw materials. Therefore, scientists did not take them into account when studying ancient building materials.
According to Admira Masik, an associate professor at the Department of Civil and Environmental Engineering at the Massachusetts Institute of Technology, it was hard to believe that ancient engineers failed in their tasks. They always carefully selected and processed materials, he writes. CNN .
According to the scientist, this new discovery will help manufacturers produce more durable and refined concrete. It was precisely this strong material that allowed the Romans to achieve an architectural revolution and build extraordinarily beautiful cities.
What else did the researchers find out?
Concrete is created by mixing cement (an inorganic hydraulic binder), fine and coarse aggregates, and water. During a study published by the journal Science Advances, scientists concluded that the methods of mixing the ingredients hold the key to the durability of ancient structures.
According to Admiral Masik, in their written testimonies about the creation of concrete, the Romans suggested using slaked lime as a binder (this is when lime is first mixed with water). Therefore, researchers initially believed that Roman concrete was made in this way.
However, laboratory analyses showed that the white lime fragments, which provided the material with stability, were formed as a result of using quicklime and at extremely high temperatures. This “hot mixing” of quicklime with other components is key to explaining the durability of the concrete.
As Admiral Masik noted, the extremely high temperature accelerates all reactions within the material and its rapid hardening. Consequently, buildings are constructed much faster.
To determine whether the white fragments matched the self-healing ability of Roman concrete, the team conducted an experiment. They created two concrete samples: one using the Roman recipe and the other according to modern standards. The researchers then deliberately cracked the samples. After two weeks, water no longer seeped through the concrete made using the Roman method, while it easily passed through the second piece of concrete.
The team stated that knowledge of such self-healing potential in concrete could pave the way for the production of a more durable modern material. According to the research, this technology will also contribute to reducing the carbon footprint of concrete, which currently accounts for up to 8 percent of global greenhouse gas emissions.
For many years, materials scientists, historians, and architects have claimed that Roman concrete was so strong due to the volcanic ash from the city of Pozzuoli. This ash, which was actively used in construction, has long been considered an important ingredient in the production of concrete.
And now scientists know another secret of the durability of ancient building material.
