{"id":29103,"date":"2023-01-10T21:29:02","date_gmt":"2023-01-10T21:29:02","guid":{"rendered":"https:\/\/mailinvest.blog\/index.php\/2023\/01\/10\/scientists-figure-out-why-roman-buildings-have-survived-for-so-long\/"},"modified":"2023-01-10T21:29:02","modified_gmt":"2023-01-10T21:29:02","slug":"scientists-figure-out-why-roman-buildings-have-survived-for-so-long","status":"publish","type":"post","link":"https:\/\/mailinvest.blog\/index.php\/2023\/01\/10\/scientists-figure-out-why-roman-buildings-have-survived-for-so-long\/","title":{"rendered":"Scientists Figure Out Why Roman Buildings Have Survived For So Long"},"content":{"rendered":"

<\/a>\n<\/p>\n

This site may earn affiliate commissions from the links on this page. Terms of use<\/a>.<\/div>\n
\n
\n
\n\"\" <\/div>\n<\/div>\n

(Image: Livioandronico2013\/Wikimedia Commons)<\/small><\/center>The Roman Pantheon, Colosseum, and other landmarks each draw more than 7 million visitors per year. It\u2019s only fair: For more than 2,000 years, the buildings have presented tangible evidence of the ancient Roman Empire. But the mere fact of the landmarks\u2019 age has long prompted scientists to wonder how the Romans managed to construct buildings with such structural integrity.<\/p>\n

Now it seems that a large team of researchers from the United States, Switzerland, and Italy has solved the puzzle. Using concrete samples from Privernum, an ancient Roman city and archaeological site, the researchers determined that lime clasts allowed cracked walls to \u201cheal\u201d\u2014and thus extend their own longevity\u2014over time.<\/p>\n

The Romans made their concrete in largely the same way we do now, using aggregate (like sand, gravel, or volcanic tuff), water, and a binding agent. Scientists previously assumed the Romans used volcanic ash as their binding agent. Historic texts indicate that ash from the area of Pozzuoli was shipped around the Roman empire and used in various forms of construction. Any white chunks found throughout the concrete were thought to be the product of poor mixing or low-quality raw material.<\/p>\n

But large-area scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS) has helped researchers identify their mistake. Rather than an indication of poor quality, the white spots within the Romans\u2019 concrete served as an independent healing mechanism for cracks that formed in the buildings\u2019 walls. The Romans used quicklime with or in place of the more traditional slaked lime (lime mixed with water) when they made their binding agents. Because quicklime is more reactive, it produced an exothermic reaction that facilitated what\u2019s known as \u201chot mixing.\u201d<\/p>\n

\"\"<\/p>\n

Original Roman lime clasts (top) vs modern recreation. (Image: Seymour et al\/Science Advances DOI 10.1126\/sciadv.add1602)<\/p>\n<\/div>\n

Hot mixing didn\u2019t just reduce the concrete\u2019s curing and setting times. It also produced high-temperature-associated compounds that slaked lime couldn\u2019t have formed. These included a nanoparticulate architecture responsible for a brittle and reactive calcium source. Any small cracks that started to form in the concrete would \u201ctravel\u201d through the lime clasts, which would react with water to produce a calcium-saturated solution. When this solution recrystallized, it would fill the cracks.<\/p>\n

The researchers sought to test Roman lime clasts\u2019 effect on modern concrete, which actually requires more repair (and emits far more carbon during manufacturing) than its predecessor. In a paper<\/a> published last week in Science Advances<\/i>, they describe the process by which they combined Ordinary Portland cement (OPC) with ash, sand, and water. They then added quicklime to some samples while leaving the others as-is. The researchers cracked all of their samples, ran water through the cracks, and then left the samples alone for two weeks.<\/p>\n

Just as the Romans intended, the samples containing lime clasts had completely \u201chealed\u201d by the end of the two-week period. Water could no longer flow through where the cracks had once been. Meanwhile, samples made without quicklime did not heal and continued to allow water to flow through their cracks.<\/p>\n

The researchers now intend on commercializing quicklime-equipped concrete. \u201cOne method to reduce cement\u2019s carbon footprint\u2026is to improve the longevity of concrete through the incorporation of self-healing functionalities,\u201d they write. \u201cThe resulting extended use life, combined with a reduction in the need for extensive repair, could thus reduce the environmental impact and improve the economic life cycle of modern cementitious constructs.\u201d<\/p>\n

Now Read:<\/b><\/p>\n<\/p><\/div>\n