Mystery of why Roman buildings have survived so long has been unraveled, scientists say
今日はローマ建築の魅力について見ていきましょう。古代ローマ時代の建築物が長持ちしたのは、コンクリートの中に石灰の塊が含まれていたからだと言われています。この白い塊は、高温の練り混ぜ工程で生成され、水にさらされると、溶解と再結晶によって自己修復することができるのです。この新しい知見は、より頑丈で持続可能な現代のコンクリートの開発につながる可能性があります。これまでローマ時代のコンクリートの強度はナポリ湾の火山灰だけで決まると考えられていましたが、今回の研究により、火山灰と石灰の両方の塊が重要な役割を担っていることが明らかになりました。(English) Today we look at the charms of Roman architecture. The longevity of ancient Roman buildings has been attributed to the presence of lime clasts in the concrete mixture. When exposed to water, these white lumps, created during a hot mixing process, can self-heal through dissolution and recrystallisation. This newfound knowledge could lead to the development of more robust and sustainable modern concrete. While volcanic ash from the Bay of Naples was previously believed to be the sole contributor to the strength of Roman concrete, the study reveals that both ash and lime clasts played a critical role.
Mystery of why Roman buildings have survived so long has been unravelled, scientists say
//Summary - Level B2//
Lime clasts in the concrete mixture are the secret to the long-lasting ancient Roman buildings. This white material, formed during hot mixing, can heal cracks over time through dissolving and recrystallising when exposed to water. This discovery can potentially improve the durability and sustainability of modern concrete. Previously, it was thought that volcanic ash from the Gulf of Naples was the main factor in the strength of Roman concrete, but the study shows that both ash and lime clasts were important.
//Summary - Level C1//
The longevity of ancient Roman buildings has been attributed to the presence of lime clasts in the concrete mixture. When exposed to water, these white lumps, created during a hot mixing process, can self-heal through dissolution and recrystallisation. This newfound knowledge could lead to the development of more robust and sustainable modern concrete. While volcanic ash from the Bay of Naples was previously believed to be the sole contributor to the strength of Roman concrete, the study reveals that both ash and lime clasts played a critical role.
A)
1)
The majestic structures of ancient Rome have survived for millennia - a testament to the ingenuity of Roman engineers who perfected the use of concrete.
2)
But how did their construction materials help keep colossal buildings like the Pantheon (which has the world's largest unreinforced dome) and the Colosseum standing for more than 2,000 years?
B)
3)
Roman concrete has often been shown to last longer than its modern equivalent, which can deteriorate within decades.
Scientists behind a new study say they have uncovered the mystery ingredient that allowed the Romans to make their building material so durable and build elaborate structures in challenging locations such as docks, sewers and earthquake zones.
4)
The study team, including researchers from the United States, Italy and Switzerland, analysed 2,000-year-old concrete samples taken from a city wall at the archaeological site of Privernum in central Italy, which is similar in composition to other concrete found throughout the Roman Empire.
5)
They found that white chunks in the concrete, called lime clasts, gave the concrete the ability to heal cracks that had formed over time.
The white chips had previously been overlooked as evidence of sloppy mixing or poor-quality raw materials.
6)
"For me, it was tough to believe that ancient Roman (engineers) would not do a good job because they were cautious about selecting and processing materials," said study author Admir Masic, an associate professor of civil and environmental engineering at the Massachusetts Institute of Technology.
7)
"Scholars wrote down precise recipes and enforced them on construction sites (throughout the Roman Empire)," Mr Masic added.
The discovery could help make the production of today's concrete more sustainable, potentially shaking up society the way the Romans once did.
8)
"Concrete allowed the Romans to have an architectural revolution," Masic said.
"The Romans were able to create and transform the cities into something extraordinary and beautiful. And that revolution completely changed the way people lived."
C)
9)
Lime clasts and the durability of concrete
Concrete is essentially artificial stone or rock formed by mixing cement, a binder typically made from limestone, water, fine aggregate (sand or finely crushed rock) and coarse aggregate (gravel or crushed stone).
10)
Roman texts had suggested using slaked lime (when lime is first combined with water before being mixed) in the binder, so scholars had assumed that's how Roman concrete was made, Masic said.
With further study, the researchers concluded that the lime clasts were created by using quicklime (calcium oxide) - the most reactive and dangerous dry form of limestone - instead of, or in addition to, slaked lime when mixing the concrete.
11)
Further analysis of the concrete showed that the lime clasts formed at the extreme temperatures expected from quicklime and that 'hot mixing' were crucial to the durability of the concrete.
12)
"The benefits of hot mixing are twofold," said Masic in a press release. "First, when the entire concrete is heated to high temperatures, it allows chemistries that are not possible when using only slaked lime, creating high-temperature-associated compounds that would not otherwise form.
Secondly, this increased temperature significantly reduces curing and setting times as all reactions are accelerated, allowing for much faster construction".
D)
13)
The team experimented with investigating whether the lime clasts were responsible for the apparent ability of Roman concrete to repair itself.
14)
They made two samples of concrete, one made to Roman recipes and the other to modern standards, and deliberately cracked them.
After two weeks, water could not flow through the concrete according to the Roman formula, whereas it passed right through the piece of concrete made without quicklime.
15)
Their findings suggest that the lime clasts can dissolve into cracks and recrystallise after exposure to water, healing damages caused by weathering before they spread.
The researchers say this self-healing potential could pave the way for producing more durable and sustainable modern concrete. According to the study, such a move would reduce concrete's carbon footprint, which accounts for up to 8% of global greenhouse gas emissions.
16)
For years, researchers believed that volcanic ash from the Pozzuoli area in the Gulf of Naples made Roman concrete so strong.
This type of ash was transported throughout the vast Roman Empire for construction and was described by architects and historians of the time as the main ingredient of concrete.
Masic stated that both components were important, but lime had been overlooked.
Here are sample answers to questions 1-10:
1. What was the secret to the longevity of ancient Roman buildings?
Answer: The secret to the longevity of ancient Roman buildings was lime clasts in the concrete mixture.
2. What are lime clasts?
Answer: Lime clasts are white lumps that form during the extreme temperatures of hot mixing.
3. How can lime clasts help repair damage to concrete structures?
Answer: Lime clasts can dissolve into cracks and recrystallise after exposure to water, repairing damage caused by weathering.
4. How does this self-healing potential of lime clasts impact the production of modern concrete?
Answer: This self-healing potential of lime clasts could produce more durable and sustainable modern concrete.
5. What was previously believed to be the primary factor in the strength of Roman concrete?
Answer: Previously, it was believed that volcanic ash from the Bay of Naples was the primary factor in the strength of Roman concrete.
6. What did the study reveal about the role of volcanic ash in the strength of Roman concrete?
Answer: The study showed that ash and lime clasts were essential and that the critical ingredient had been overlooked.
7. What is the main takeaway from the study regarding the longevity of ancient Roman buildings?
Answer: The main takeaway from the study is that using lime clasts in the concrete mixture was the secret to the longevity of ancient Roman buildings.
8. How does the discovery of lime clasts impact our understanding of ancient Roman construction techniques?
Answer: The discovery of lime clasts changes our understanding of ancient Roman construction techniques by revealing a previously overlooked critical ingredient in the strength of Roman concrete.
9. How does this study have implications for modern concrete production?
Answer: The study has implications for modern concrete production by potentially improving the durability and sustainability of contemporary concrete through self-healing materials like lime clasts.
10. What was the significance of the findings of this study?
Answer: The significance of the findings of this study is that they show the potential for producing more durable and sustainable modern concrete and shed new light on ancient Roman construction techniques.
Here's the list of new words from the article at a B2 level with sample sentences:
Longevity - the ability to last for a long time.
(Ex) The longevity of a good marriage depends on the effort both partners put into it.
Lime clasts - white lumps that form during the hot mixing process of concrete.
(Ex) The lime clasts in the ancient Roman concrete were the secret to its longevity.
Recrystallise - to form crystals again.
(Ex) After being exposed to water, the lime clasts in the concrete recrystallised, repairing cracks.
Weathering - the process by which the elements wear away the surface of a material.
(Ex) The weathering of the old wooden bridge was visible in the deep cracks and missing boards.
Durable - able to withstand wear and tear for a long time.
(Ex) A durable backpack is a must for frequent travellers who need to carry their belongings on their adventures.
Sustainable - able to be maintained at a certain level without depleting natural resources.
(Ex) A sustainable lifestyle balances economic development with the preservation of the environment.
Self-healing - the ability to repair oneself.
(Ex) The self-healing skin of a cut finger is a remarkable example of the body's natural processes.
Strength - the quality of being strong and having the ability to resist stress.
(Ex) The power of the steel structure was critical to the safety of the high-rise building.
Critical ingredient - an essential component or factor.
(Ex) The crucial ingredient in the cake recipe was the right mix of flour, sugar, and eggs.
Implications - the possible consequences or effects of something.
(Ex) The impact of climate change on the world's ecosystems is far-reaching and complex.
Crucial - Extremely important or necessary.
(Ex) The crucial support from the community helped the small business to survive during the pandemic.
//Discussion//
1. Would it be beneficial for humanity to unlock the architectural secrets of ancient Rome in modern times?
-> It would be beneficial for humanity to unlock the architectural secrets of ancient Rome as they have been able to endure for centuries, and modern buildings could benefit from such knowledge.
2. Why do you think ancient Roman architecture was able to develop in such an excellent way?
-> Ancient Roman architecture was able to develop excellently due to its advanced engineering techniques, innovative materials, and strong cultural heritage.
3. What trivia about Rome do you know?
For example, places of interest in Rome: Colosseo, famous people: Caesar, Greek and Roman mythology, films: Roman holidays, etc.
-> Some trivia about Rome that I know is that it was founded in 753 BC and was once the centre of the world as the capital of the Roman Empire. Famous places of interest include the Colosseum and the Roman Forum.
4. Are disasters such as volcanoes or earthquakes common in your country?
-> Disasters such as earthquakes and volcanic eruptions are not common in my country but can still occur.
5. Do you think architecture is a form of art? What famous buildings are you aware of?
-> I believe architecture is a form of art as it showcases creativity, imagination, and a cultural representation of society. Some famous buildings I am aware of include the Great Wall of China, the Eiffel Tower, and the Burj Khalifa.
MYSTERY of why Roman buildings have survived so long has been unravelled, scientists say
https://edition.cnn.com/style/article/roman-concrete-mystery-ingredient-scn/index.html