Analysis of Roman Concrete Ingredients Reveals Ancient Techniques at Pompeii

Admir Masic of the Massachusetts Institute of Technology and his colleagues analyzed building materials discovered in a complex at Pompeii that includes a bakery and living areas. The structures were under renovation when Mount Vesuvius erupted in A.D. 79, burying the city in volcanic ash and preserving the work in progress at the bakery.

Masic stated that the building materials demonstrate that the workers used a technique called hot mixing to make concrete as needed with quicklime, water, and a blend of volcanic rock and ash. This combination produces heat in a chemical reaction.

Interestingly, this method contradicts a recipe written by the Roman architect and engineer Vitruvius in the first century B.C. Roman hot-mixed concrete contains remnants of lime from the reaction called lime clasts, which can dissolve, recrystallize, and repair cracks on its own.

Masic noted this makes it an improvement over the concrete described by Vitruvius. He explained that this hot-mixed concrete allowed builders to construct massive monolithic structures, complex vaults and domes, and harbors with concrete that cured underwater.

The original scholarly article about this research was published in Nature Communications. For more on Roman concrete structures, the report suggests visiting 'Rome's Lost Aqueduct.'