Pompeii still amazes: new data on Roman buildings emerge from the excavations underway at the Archaeological Park. In the environments of ancient domus that the archaeological excavation is bringing to light in Regio IX, insula 10, important evidence of a construction site in full activity has re-emerged: work tools, tiles and tuff bricks stacked up and piles of lime.


"Pompeii is a treasure chest - declares the Minister of Culture, Gennaro Sangiuliano - and not everything has been revealed in its full beauty. A lot of material has yet to emerge. In the last Budget Law we financed new excavations throughout Italy and an important part of this allocation is intended for Pompeii. I was very pleased when the director of the Archaeological Park, Gabriel Zuchtriegel, recalled that, never before have so many excavations been active on the site: we can say that it is a record of the last decades. At the same time we are also working on other fronts. In recent months the Minister of Defense, Guido Crosetto, handed over the Torre Annunziata Spolettificio to the Ministry of Culture, where a large museum will be created to collect all these finds" .

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Pompeii, from the excavation of Regio IX new light on the secrets of Roman construction

According to scholars, the construction site was active until the day of the eruption of Vesuvius in 79 AD, which began around lunchtime and lasted until the morning of the following day. The excavation in the area in question, aimed at regulating the hydrogeological structure along the border between the excavated and unexcavated parts of the Roman city, is attesting to the presence of an ancient building site that affected the entire block. Particularly numerous is the evidence of the work in progress in the house with the Rustio Vero bakery, where a still life with the depiction of a focaccia and a glass of wine has already been documented in recent months.


The atrium was partially uncovered, materials for the renovation were piled up on the ground and on a door of the tablinum (reception area), decorated in the 4th Pompeian style with a mythological painting of "Achilles on Skyros", those can still be read today which were probably the construction site's counts, or Roman numerals written in charcoal, easily erasable unlike the graffiti engraved in the plaster. 

Traces of ongoing activities are also found in the environment that housed the lararium, where amphorae reused to "extinguish" the lime used in applying the plaster were found. Construction tools were discovered in various rooms of the house, from the lead weight for pulling up a perfectly vertical ("plumb") wall to the iron hoes used for preparing the mortar and working the lime. Even in the nearby house, reachable from an internal door, and in a large residence behind the two houses, which has so far only been partially investigated, numerous testimonies of a large construction site have been found, also attested by the enormous piles of stones to be used in the reconstruction of the walls and amphorae, ceramics and tiles collected to be transformed into cocciopesto.


This is an "extraordinary opportunity to experiment with the potential of close collaboration between archaeologists and materials scientists", write the authors of an article published in the E-Journal of the Pompeii Excavations. In the analysis of materials and construction techniques, the Pompeii Archaeological Park availed itself of the support of a group of experts from the Massachusetts Institute of Technology, USA. "The hypothesis put forward by the team is that of hot mixing, i.e. mixing at high temperatures, where quicklime (and not slaked lime) is premixed with dry pozzolan and subsequently hydrated and applied in the construction of the opus caementicium" , we read in the text. Normally, quicklime is immersed in water, i.e. "quenched", long before use on the construction site, forming the so-called slaked lime, a material with a plastic consistency. “Quenching,” or the reaction between quicklime and water, produces heat. Only at the time of implementation, the lime is then mixed with sand and aggregates to produce the mortar or cement.


In the case of the Pompeii construction site, however, it appears that the quicklime, i.e. not yet brought into contact with water, was initially mixed only with pozzolanic sand. While the contact with the water occurred shortly before the wall was installed. This means that, during the construction of the wall, the mixture of lime, pozzolanic sand and stones was still hot due to the ongoing thermal reaction and consequently dried more quickly, shortening the construction time of the entire construction. Differently, when it came to plastering the walls, it seems that the lime was first slaked and then mixed with the aggregates to then be spread, as is still done today. 

"The excavation in Regio IX, insula 10, planned in the years of the Great Pompeii Project, is yielding, as expected, important results for the knowledge of the ancient city. An interdisciplinary research site, born like the previous excavation of Regio V, from the necessity to secure the excavation fronts, i.e. the walls of eruptive material left by the excavations of the 19th and 20th centuries which loom dangerously over the excavated areas. Pompeii continues to be a permanent construction site where research, safety, maintenance and use are connected activities and daily practice", says the general director of the Museums, Massimo Osanna.

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Pompeii, from the excavation of Regio IX new light on the secrets of Roman construction

"It is a further example - underlines the Director of the Park, Gabriel Zuchtriegel - of how the small city of Pompeii makes us understand many things about the great Roman Empire, not least the use of cement. Without the cement we would not have the Colosseum , nor the Pantheon, nor the Baths of Caracalla. The excavations underway in Pompeii offer the possibility of observing almost directly how an ancient building site functioned. The data that emerge seem to point to the use of quicklime in the construction phase of the walls, a practice already hypothesized in the past and capable of significantly speeding up the time of a new construction, but also of a renovation of buildings damaged, for example by an earthquake. This seems to have been a very widespread situation in Pompeii, where work was underway for a almost everywhere, so it is probable that after the great earthquake of 62 AD, seventeen years before the eruption, there had been other seismic shocks that hit the city before the cataclysm of 79 AD. Now we are networking between research institutions to study the constructive know-how of the ancient Romans: perhaps we can learn from them, let's think about sustainability and the reuse of materials".

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Pompeii, from the excavation of Regio IX new light on the secrets of Roman construction