The ancient Romans have made some substantial contributions to history – and researchers are still uncovering more. Now, they have unearthed a construction site preserved exactly as it was when Mount Vesuvius erupted in 79 AD, providing an unprecedented insight into the durable, ‘self-healing’ concrete that revolutionised Roman architecture. Another reason why it is so exciting is because it shows a building project abruptly halted by the volcanic catastrophe. (Picture: Archaeological Park of Pompeii)
The researchers found rooms with unfinished walls, alongside piles of premixed dry materials and tools for weighing and measuring, all laid out for concrete preparation. Roman concrete was an indispensable material, enabling the construction of monumental structures such as the Colosseum, the Pantheon, public baths, aqueducts and bridges, which were all feats of engineering unparalleled at the time. (Picture: Getty)
Lead author Professor Admir Masic said: ‘There is the historic importance of this material, and then there is the scientific and technological importance of understanding it. This material can heal itself over thousands of years, it is reactive, and it is highly dynamic. It has survived earthquakes and volcanoes. It has endured under the sea and survived degradation from the elements. We don’t want to completely copy Roman concrete today. We just want to translate a few sentences from this book of knowledge into our modern construction practices.’ (Picture: Vaserman, E., Weaver, J.C., Hayhow, C. et al.)
The exact methods the Romans used have been long debated, and recent archaeological findings often challenge accounts from the 1st-century BC work by architect Vitruvius. But the new discovery shows the Romans used a technique called ‘hot mixing’ in which a material called quicklime- dry limestone that was previously heated – is combined directly with water and a blend of volcanic rock and ash, producing a chemical reaction that naturally heats the mixture. (Picture: Vaserman, E., Weaver, J.C., Hayhow, C. et al.)
Professor Masic said: ‘Pompeii preserves buildings, materials and even work in progress in the precise state they were in when the eruption occurred. Unlike finished structures that have undergone centuries of repair or weathering, this site captures construction processes as they happened. For studying ancient technologies, there is simply no parallel, its exceptional preservation offers a true ‘snapshot’ of Roman building practice in action.’ (Picture: Vaserman, E., Weaver, J.C., Hayhow, C. et al.)
The building that was being constructed had domestic rooms with a working bakery with ovens, grain-washing basins and storage. The evidence indicated that the technique outlined by Vitruvius, known as slaked lime, was not used for building walls. The hot-mixing technique contributed to the self-healing properties of the concrete, chemically repairing cracks through the white remnants of the lime used to make it, called ‘lime clasts’, which can dissolve and recrystallise, healing cracks that may form with the infiltration of water. (Picture: Salvatore Laporta/KONTROLAB/LightRocket via Getty Images)
Professor Masic said that when he first entered the Pompeii site and inspected the perfectly preserved work area, tears came to his eyes. He said: ‘I expected to see Roman workers walking between the piles with their tools. It was so vivid, you felt like you were transported in time. So yes, I got emotional looking at a pile of dirt. The archaeologists made some jokes.’ (Picture: Silvia Bazzicalupo/Anadolu Agency via Getty Images)
