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Roman concrete was used to construct the magnificent pantheon, which has endured for two millennia.

Researchers discover secret recipe of Roman concrete that allowed it to endure for over 2,000 years

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Ancient Rome’s concrete recipe is an impressive feat in architectural history. Some Roman buildings are so spectacular in their construction and beauty that modern builders would never attempt something similar, even with today’s technology. Now engineers are beginning to understand why ancient Roman concrete was so revolutionary.

Rome built many of its buildings and monuments with concrete made of lime, volcanic sand, and volcanic rock. The ancient Romans’ buildings and structures, some of the most spectacular in the world, have withstood chemical and physical onslaught for 2,000 years and are still standing.

An advanced concrete recipe allowed the Romans to constructed magnificent structures that no builder would dare to attempt today

An advanced concrete recipe allowed the Romans to constructed magnificent structures that no builder would dare to attempt today. Source: BigStockPhoto

Previous research has already found that Roman concrete was far superior to our own modern concrete, which is made to endure about 120 years.

It’s been known for a while that the volcanic sand used in Roman concrete and mortar made their buildings last for so long.  Now a new study by a group of engineers and engineering researchers has discovered the precise recipe that made the Roman concrete endure much longer than concrete used today.

The researchers used an ancient recipe written down by Roman architect Vitruvius to mix a batch of mortar. The engineers let it harden for six months and looked at it with microscopes. They found that clusters of a dense mineral form through the Roman process. These strätlingite crystals, formed by the volcanic sand as it binds with limestone, prevented the spread of cracks by reinforcing interfacial zones. Interfacial zones are weak links inside the concrete.

A magnified piece of Roman concrete consisting of lime, volcanic sand, and rock

A magnified piece of Roman concrete consisting of lime, volcanic sand, and rock ( Wikimedia Commons )

It isn’t just that Roman concrete is more lasting. It is also not as bad for the environment in the manufacturing of it because the mix only needed to be heated to 900 Celsius as opposed to the 1,450 of modern concrete.

“Stronger, longer-lasting modern concrete, made with less fuel and less release of carbon into the atmosphere, may be the legacy of a deeper understanding of how the Romans made their incomparable concrete,” Ancient-Origins.net wrote in 2013 . Heating the limestone in 19 billion tons of Portland cement made annually accounts for 7 percent of human-released carbon into the atmosphere, according to the new study .

Ceiling in the Pantheon, made entirely from Roman concrete

Ceiling in the Pantheon, made entirely from Roman concrete. Credit: Giulio Menna / flickr

Rome is situated between two volcanic regions, Monti Sabatini to the north and the Alban Hills to the south. When Augustus became the first emperor of Rome in 27 AD, he initiated a building campaign. After builders settled on using Pozzolonic ash from the Alban Hills’ Pozzolane Rosse ash flow, Augustus decreed that Pozzolonic  mortar be the standard in Roman buildings. That decision cemented Rome’s enduring architectural legacy. Roman architects found that this mortar substantially improved the margin of safety in buildings, which were becoming more daring in their design.

The prototypical example of this may be the awe-inspiring Roman Pantheon, a huge concrete building capped by 142-foot dome. It was built in the second century AD.

The Roman Panethon, a huge concrete building that has endured for nearly 2,000 years

The Roman Panethon, a huge concrete building that has endured for nearly 2,000 years. Source: BigStockPhoto

“Made entirely out of concrete, without the reinforcing support of structural steel, no modern engineer would dare attempt such a feat, says David Moore , author of The Roman Pantheon: The Triumph of Concrete . ‘Modern codes of engineering practice would not permit such mischief,’” Smithsonian.com says .

Featured image: Roman concrete was used to construct the magnificent pantheon, which has endured for two millennia. Source: BigStockPhoto.

By Mark Miller

Comments

Very interesting.

Whether concrete, steel or stone, bridges will always need maintenance because of the action of the water, specifically in undermining them. Modern concrete also gets harder for decades and if properly mixed and cured, will endure for centuries. However, it's remarkable that concrete has been around so long.

But bridges in the united states are lucky to last 50 years. Add in all the traffic and chemicals put on the roads and some last less. Maybe the golden gate,( but it has impeccable upkeep and great weather),. but most bridges in this country dont even have a 75 year lifespan.
Its a serious problem in our country (road infrastructure)along with the opioid epidemic

Also, salt water of any kind is modern concretes worst nightmare

Um... I realize this post is a couple of years old, but thought it prudent to mention: the article stated that modern concrete lasts about 120 years. Your "friend" claims that the cement used in the SF bridge would last a century. But you seem puzzled...?

A century = 1oo years, so if the article claims roughly 120 years, it would seem to be within the margin of error and corroborate your friend's claim.

So... again, why are you puzzled?

Modern concrete may tolerate hundreds of thousands of vehicles across it every day, but that's because of the iron bars used to reinforce it. Just try using non reinforced modern concrete in a seismically active region and build something like the Pantheon (which has lasted around two thousand years without care and maintenance). Oh, and about St. Paul's in Macau? The last time I saw it, it was buttressed by steel girders on the reverse side. But all of that is moot. There is scientific evidence now that Roman concrete formulations using less energy, actually do have chemical differences on the microscopic level that impart strength over time that isn't found in modern concrete. In other words, it's better concrete. Whether or not our modern concrete being worthy is immaterial; Roman concrete is certainly worthier and science just proved it.

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