How the Pantheon has stayed intact for almost 2,000 years: Study reveals how small chunks of lime gave Roman concrete 'self-healing' capabilities

Daily Mail UK ^ | January 6, 2023 | Xantha Leatham, Deputy Science Editor

[SunkenCiv]

It's a riddle that has left engineers scratching their heads for a very long time.

How is it that Rome's famed Pantheon has stayed intact for almost 2,000 years while many modern concrete structures crumble after just a few decades?

Now, researchers may have finally discovered the secret behind ancient construction methods – and it's all to do with tiny pieces of lime that come with 'self-healing' capabilities.

Close analysis of Roman concrete has revealed tiny, bright white mineral chunks called 'lime clasts'...

And they discovered the lime may actually help the concrete 'heal' itself when it cracks or breaks.

During the hot mixing process needed to make concrete, the lime clasts become brittle – creating an easily accessible source of calcium for the rest of the concrete.

This means that when tiny cracks form in the concrete, the lime clasts react with water and create a calcium-saturated solution, which can recrystallize and quickly fill the crack.

Initially, it was thought these were present as a result of sloppy mixing practices, or using poor-quality raw materials...

To prove that this was indeed the mechanism responsible for the durability of the Roman concrete, the team produced samples of hot-mixed concrete that incorporated ancient formulations, deliberately cracked them, and then ran water through the cracks.

Within two weeks the cracks had completely healed and the water could no longer flow.

An identical chunk of concrete made without the lime never healed, and the water just kept flowing through the sample.

As a result of these successful tests, the team is working to commercialize the modified cement material.

[SunkenCiv]

The rest of the Roman Concrete keyword, sorted:

• Why was Roman Concrete Forgotten during the Middle Ages? [11/14/2021]
• Sinkhole opens near the Pantheon, revealing 2,000-year-old Roman paving stones [05/13/2020]
• Science reveals improvements in Roman building techniques [10/30/2019]
• Paleomagnetism Study Supports Pyramid Man-Made Stone [02/19/2018]
• Finding a new formula for concrete [05/28/2016]
• Back to future with Roman architectural concrete [12/19/2014]
• To improve today's concrete, do as the Romans did [06/05/2013]
• The Riddle of Ancient Roman Concrete [09/02/2011]
• Volcanic ash may have preserved Roman ruins (Good cement) [05/14/2009]
• Researcher investigates ancient geology to understand human development, climate change [10/11/2008]
• Ancient Rome's Earliest Temple Reconstructed [03/15/2008]
• 'Caesar's superglue' find [12/04/2007]
• Research team recreates ancient underwater concrete technology [04/09/2005]

[SunkenCiv]

The other GGG topics added since the previous digest ping, chrono sort:

• Ancient code in Ice Age drawings solved [01/06/2023]
• Old Nazi map sparks treasure hunt in the Netherlands [01/06/2023]
• Ww2 Treasure Map Released to Public [01/06/2023]
• Woman finds out she is her daughter's mother - and uncle [01/06/2023]
• Sorry William, No Conquering Now: EU Red Tape Prevents Construction Of A Replica Ship From 1066 [01/05/2023]
• The Untold Story Of Emperor Vespasian [1:16:04] [01/05/2023]
• Forgotten Prelude To WW1 -- Italo-Turkish War 1911-1912 (History Documentary) [31:39] [01/05/2023]
• Hundreds of 4,500-yr-old tombs found in central China [01/04/2023]
• Siberian Gravediggers Find 2,000 Year Old Scythian-style Cemetery [01/04/2023]
• Metallurgical Fingerprint Points to Lost Roman Legion [01/04/2023]
• Spanish Egyptologists unearth 60 mummies at Luxor site [01/04/2023]
• Humans have been using bear skins for at least 300,000 years, suggests study [01/04/2023]
• Ancient hunter-gatherers were potters, too [01/04/2023]
• Great Battles: Was there a Trojan War? Recent Excavations at Troy [01/04/2023]
• How did the Romans Prove Their Identity? [01/04/2023]
• Circe, the First Witch of Greek Mythology [01/03/2023]
• Pharaoh's 'handsome' face seen for first time in 3,200 years in reconstruction [01/03/2023]
• Archeologists Have Uncovered Hidden Hieroglyphs in King Tut's Tomb That May Point to the Secret Location of Queen Nefertiti's Remains [01/02/2023]
• Nuralagus rex: Giant extinct rabbit that didn't hop [01/01/2023]
• Stone Giant Unearthed Among God Heads At Aizanoi [12/31/2022]
• Cezanne Self-Portrait Hidden Under a Still Life Is Discovered After Almost 160 Years [12/23/2022]

[Jonty30]

That is neat.

[Hootowl99]

Next…

I'd like to see supercharged lime clasts that can eliminate driveway cracking caused by poor base preparation before laying down the concrete slab.

[SunkenCiv]

It’s still the largest unreinforced concrete dome in the world.

[Right_Wing_Madman]

The two most astonishing mad-made objects I've seen with my eyes are the Great Pyramid in Egypt and the Pantheon in Rome. The Pantheon is the most solid, most impressive architectural structure I've seen and when inside the building, it feels like its 2,000 years old. There's nothing else like it. It's hard to describe.

[mairdie]

You put up the BEST articles!

[algore]

More info

https://news.mit.edu/2023/roman-concrete-durability-lime-casts-0106

[Adder]

Oh wow.
The saying is “Concrete always cracks” and that is certainly true of modern concrete...you just try to control where and how much it cracks.

But then I looks at that magnificent dome sitting there for 2.000 years with nary a crack or spall and its amazing.

The Pantheon is just a marvel. An amazing building.

[Ann Archy]

Everyone should visit The Pantheon!! October will be visiting the Great Pyramids!!

[Roccus]

FTA

Initially, it was thought these were present as a result of sloppy mixing practices, or using poor-quality raw materials

Reminded me of some of the things Thor Heyerdahl found out about the genius of ancient naval architects in his construction of Ra

[Sicon]

Haven’t seen the pyramids in person, but have been inside the Pantheon. Absolutely incredible. Even in a city like Rome, filled with numerous awe-inspiring examples of the brilliance of Roman engineering, the Pantheon stood apart for its beauty and durability.

[wgmalabama]

Good post. Thanks for posting all these types of articles.

[CoastWatcher]

The real mystery is how the Roman use of lime influenced a Greek structure that preceded it by a 1,000 years.

[CoastWatcher]

Never mind - dyslexic. Read Parthenon.

[1FreeAmerican]

Very cool. Thanks!

[moovova]

Not bad...considering the Pantheon has a huge hole in its roof.

[moovova]

[SomeCallMeTim]

I agree. It’s an incredible building. A MUST see on any visit to Rome.

[SunkenCiv]

And it's adorable that Roman errors were seen where none existed, even though no one alive today, even now, could reproduce the Pantheon dome.