The circulation of building materials: pozzolana in the Baroque Dubrovnik

The paper investigates the introduction into Early Modern building practice in the Republic of Ragusa (Dubrovnik) of pozzolana, a component of hydraulic cement, thus extending the area where it was known to have been used in the Baroque era. The documents in the State Archive in Dubrovnik reveal that this granulate was first sent to Dubrovnik – along with projects and a master-builder from Rome – on the occasion of the rebuilding of the cathedral after the great earthquake of 1667. The scepticism of Dubrovnik authorities towards the new material is analogous to the almost contemporary French discussion relating to Bernini’s Louvre. By contrast, the 18th-century Ragusan documents express the necessity of pozzolana for the hydraulic works commissioned from the Roman architect Pietro Passalacqua, in a manner similar to those for contemporary projects in Ancona or Venice. These episodes illustrate an otherwise poorly-documented process of changing building technology, and they introduce the importance of pozzolana in the epistemology of architecture as one of the materials which is not only resistant to water but also is effective in resisting the actions of frequent earthquakes