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Researchers finally discover why ancient Roman buildings last a long time: Okezone techno

LEAVES the ancient Romans are still visible today. Of course this is quite surprising because in ancient times the technology was not as advanced as it is today.

However, there were indeed skilled builders and engineers involved in the construction. One of the most famous is represented by a functioning aqueduct. And that architectural marvel depended on a unique building material: pozzolanic concrete, an extremely strong material that gave Roman structures incredible strength.

Even today one of their structures, the Pantheon, still intact and almost 2,000 years old, holds the record for the largest unreinforced concrete dome in the world.

These properties of concrete are generally attributed to its ingredients: pozzolana, a blend of volcanic ash named after the city of Pozzuoli in Italy, where substantial deposits of lime and limestone have been found. When mixed with water, the two ingredients can react to produce strong concrete.

An international research team led by the Massachusetts Institute of Technology (MIT) has discovered that not only are the ingredients slightly different than we think, but the techniques used to mix them are also different.

His smoking gun is the tiny lumps of white chalk that can be found in the seemingly well-mixed concrete. The presence of these lumps has previously been associated with poor mixing or materials, but that didn’t make sense to MIT materials scientist Admir Masic.

“The idea that the presence of this plaster fragment is simply associated with poor quality control has always bothered me,” Masic said.

“If the Romans put so much effort into making incredible building materials, following all the detailed recipes optimized for centuries, why did they put so little effort into ensuring the production of a well-mixed final product? There must be more secrets,” explains Lui .

Masic and his team, led by MIT civil engineer Linda Seymour, pored over 2,000-year-old Roman concrete samples from the Privernum archaeological site in Italy. These samples were subjected to large area scanning electron microscopy and energy dispersive X-ray spectroscopy, X-ray diffraction, and confocal Raman imaging to gain a better understanding of the chalky fragments.

One of the questions is the nature of the lime used. The standard understanding of pozzolanic concrete is the use of slaked lime. First, limestone is heated to high temperatures to produce a highly reactive caustic powder called quicklime or calcium oxide.

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By mixing lime with water, lime putty or calcium hydroxide is obtained: a slightly less reactive and less caustic paste. According to the theory, lime is an ingredient that the ancient Romans mixed with pozzolana.

Based on the team’s analysis, the lime class in their sample was not consistent with this method. In contrast, the Roman concrete was likely made by directly mixing lime with pozzolan and water at very high temperatures, either alone or with the addition of slaked lime, a process the team calls additive that produces slaked lime.

“First, when the entire concrete is heated to a high temperature, it allows for a chemistry that would be impossible if only slaked lime were used, resulting in high temperature-related compounds that would not form. Second, this increase in temperature it significantly reduces the hardening and curing processes,” he explained.

Then the team tested their findings by producing pozzolanic concrete from ancient and modern recipes using quicklime. They also made lime-free control concrete and performed crack tests. Sure enough, the cracked lime concrete cured completely within two weeks, but the control concrete remained cracked.

The team is now working to commercialize their concrete as a more environmentally friendly alternative to today’s concrete. “It is very interesting to think about how this more durable concrete formulation could not only extend the life of this material, but also how it could increase the life of 3D printed concrete formulations,” said Masic.

The content below is presented by the advertiser. Okezone.com journalists are not involved in this content material.

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