Geochemical and petrophysical characterization of volcanic raw materials with pozzolanic activity used in Roman ancient mortars: some case study

Volcanic rocks are commonly used as aggregate or pozzolan in ancient mortars. Generally natural pozzolans are pyroclastic rocks with rhyolitic composition and high amount of glass. In ancient Greece the mortars were prepared using the volcanic tuff from Santorini island. In Roman times the mortars of several monuments were prepared with pozzolans from Pozzuoli (near to Vesuvius volcano), as the famous Pantheon and Collesium in Rome. The artificial pozzolans represented by ceramic products (cocciopesto), as bricks, pottery and tiles. The Romans used both kinds of pozzolans to give hydraulic characteristics to the mortars, conglomerates and concretes exposed to the presence of moisture or water (e.g., foundations, rudus of floors, trullisatio-plasters, cisterns, wells, aqueducts, thermal baths). This work shows a comparison of geochemical, petrographic and physical characterization by OM, SEM-EDS, XRF, XRD, TGA-DSC analysis, He-porosimetry and PLT test of pozzolanic volcanics used in the mortars of some ancient Italian Roman building.