Roman concrete could repair its own cracks.
Some Roman buildings have stood for 2,000 years, while modern concrete can start to crumble within decades. For a long time, scientists did not fully understand why.
The Romans made their concrete from lime, water and volcanic ash from the area around Pozzuoli, near Naples. The ash reacted with the lime and created a material that grew stronger over time instead of weaker.
In 2023, a team from MIT led by Admir Masic found another piece of the puzzle, small white lumps of lime scattered through the concrete.
Scientists had always thought these lumps were a sign of careless mixing. In fact, they were the repair kit. When a crack forms and rainwater gets in, the lime dissolves and refills the crack with new mineral, sealing it from the inside.
The secret was “hot mixing.” Instead of using slaked lime, the Romans added quicklime directly to the mix. It heated up as it reacted with water and left these lumps behind on purpose.
To test the idea, the team cracked samples of concrete made with the Roman method and let water run through them. Within two weeks, the cracks had sealed completely. In concrete made without the lime lumps, the water kept flowing.
Roman harbour concrete went even further. Pliny the Elder wrote that once it touched the waves, it became a single block of stone that grew stronger every day. In 2017, geologist Marie Jackson showed he was right, seawater slowly grows rare crystals inside the concrete that hold it together.
たぬきちは何度指摘されてもデマの拡散を止めないのね。反論あるなら具体的な箇所を指摘して反論してね。成功例として引合いに出される、英国(正確にはイングランド)とオーストラリアと比較。死亡率は右側。日本では2020〜2024年に一人いるから他よりは多いが「日本でも接種推進を!! 」は欺瞞
に満ちているとよく分る。売るための宣伝文句を、推進側が元データも調べず拡散してるだけだと気付こう。
また当り前だが、日本の2020〜2024年で1人ということは4年間はゼロだったという意味。この期間の20歳〜24歳は、1996年から2004年の生まれで、接種がほぼゼロだった2001年以降の世代も含んでいる。
出典:
イングランド
Peter Sasieni, Milena Falcaro, The Lancet(BBC News掲載の死亡数)。
死亡率はONSの女性20-24歳人口推計(mid-year population estimates, 2001-2024)を用いて算出(2000年のみ2001-2004年平均で補完した近似値)。
BBC記事:
https://t.co/JAcUXG31F0
Lancet論文:
Sasieni P, Falcaro M. Cervical cancer mortality trends following HPV vaccination in England, 2001-24. Lancet. 2026.
https://t.co/hoBRiEnNjH
人口データ出典:
ONS, Estimates of the population for England and Wales
https://t.co/ZJbS5LINjz
日本
厚生労働省 人口動態統計(国立がん研究センター がん情報サービス「がん統計」より集計、死亡数・死亡率(人口10万対)ともに公式データ)。
日本の元データ(Excel):
cancer_mortality(1979-2024)H27.xls
集計表ダウンロードページ:
https://t.co/z6R79h8S9T
オーストラリア
AIHW(Australian Institute of Health and Welfare)National Mortality Database(死亡数・年齢別粗死亡率(人口10万対)ともに公式データ。2024年は推計値)。
元データ(Excel):
Cancer data in Australia 2025, Book 2a – Cancer mortality (age-standardised rates and 5-year age groups)
https://t.co/xe5eiYkDsy