GEOCHEMICAL AND ENGINEERING GEOLOGICALPROPERTIES OF THE VOLCANIC TUFFS USED INTHE ETRUSCAN TOMBS OF NORCHIA (NORTHERNLATIUM, ITALY) AND A STUDY OF THE FACTORSRESPONSIBLE FOR THEIR RAPID SURFACE ANDSTRUCTURAL DECAY

摘要

The geochemical and engineering geological properties of the tuffs used in the rock-cut clifftombs of the Etruscan necropolis of Norchia were investigated to evaluate their susceptibilityto different weathering agents and confirm their origin. For the first time, materials werecharacterized by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy(FT–IR), thermogravimetric analyses (TGA, DGA and DTG), scanning electron microscopy(SEM–EDS) and energy-dispersive X-ray fluorescence (ED–XRF), and their different originsconfirmed. Tests of material properties indicate that both tuffs are poorly durable, but oneof them is less susceptible to weathering. Although tombs made with the more resistantmaterial show limited surface weathering, they undergo severe structural damage becauseof stress release and plant root infiltration. This, combined with the microclimatic conditionsestablished inside river canyons, can trigger rock falls, leading ultimately to the completedestruction of these tombs.