Researchers have been granted an extraordinary look at old Roman engineering. Share Article Share Article Facebook X LinkedIn Reddit Bluesky Email Copy Link Link copied Bookmark Comments
An unfinished construction zone in Pompeii is offering researchers a remarkable peek into historic Roman technology. It has exposed how constructors were able to produce concrete sufficiently robust to construct an empire that encompassed around 1.9 million square miles at its height, expanding from Britain to North Africa and the Middle East, encompassing approximately 20% of the global population at that time.
Indeed, the discovery has unveiled methods that render Roman concrete significantly more enduring than many contemporary counterparts. The success of this concrete remains highly evident today, with numerous edifices like bridges, aqueducts and communal buildings still upright after almost 2,000 years, including the Colosseum in Rome, France’s Pont du Gard and the Tower of Hercules in Spain, a beacon still operational at present.
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In 2023, MIT Associate Professor Admir Masic and his group performed an analysis that implied Romans employed a technique recognised as hot-mixing, blending lime particles with volcanic ash and supplementary dry elements before incorporating water to fashion their concrete.
Remarkably, as water met the dry mixture, it generated warmth and shielded the reactive lime within the concrete. As the substance solidified, the lime developed minute clusters that later disintegrated into fissures, enabling the concrete to mend itself.
Nonetheless, the depiction challenged the writings of Vitruvius, the 1st century BC architect whose treatise, “De architectura”, endures as a foundation of architectural history. Vitruvius portrayed a procedure wherein lime was initially merged with water to generate a paste. Prof Masic expressed that reconciling his team’s outcomes with such an authoritative text proved challenging.
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Microscopic and compositional analysis of the pre-mixed (PM) dry materials pile, pozzolanic mortars in two unfinished wall structures (W1 and W2), and the mortar utilized for wall repairs (MR). pic.twitter.com/WNQCslxIc7
— Tom Marvolo Riddle (@tom_riddle2025) December 10, 2025
However, everything shifted when archaeologists unearthed an exceptionally preserved construction location in Pompeii. Encompassed by the explosion of Mount Vesuvius in 79 CE, the locale had sustained raw material stacks, implements and walls in diverse phases of completion, presenting a singular sight into Roman construction technology.
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Prof Masic’s group scrutinised samples from the area, which intensely backed his hot-mixing approach. Researchers detected lime fragments matching those observed in prior analyses, alongside complete quicklime segments pre-mixed with volcanic ash, which were explicit indications of a dry preparation phase before the infusion of water.
Associate Professor Kristin Bergmann subsequently utilised sophisticated chemical examinations (termed stable isotope analyses) to scrutinise the age-old substances. This permitted them to differentiate the Roman hot-mixed lime from the conventional, pre-mixed lime (designated “slaked lime”). The outcomes reveal that Roman builders pulverized quicklime to a precise dimension, combined it dry with volcanic ash, then introduced water to compose a binding framework. The volcanic pumice elements persisted to react with pore liquids over duration, generating novel mineral sediments that reinforced the concrete as it matured.
Prof Masic depicted entering the safeguarded worksite as resembling stepping into a “time capsule,” with substances halted in situ at the instant of construction. He appended that comprehending this archaic technology could even aid contemporary engineers in devising more resilient, self-mending building substances.