Preliminary contribution on durability of some macroporous monumental stones used in hystorical towns of Campania region, Southern Italy

Publisher Summary In Campania region (Southern Italy), the large availability of volcanic products determined the utilization of these products for structural purposes. Neapolitan Yellow Tuff (NYT), Campanian Ignimbrite (CI), and Piperno (PI) were the most widely used volcanic products in historical architecture of Campania region.. This chapter describes the mineralogical and petrographical features of these materials and the research conducted to study the decay phenomena by means of laboratory simulations, which reproduce the aging processes of the stone. Mineralogical characterization was carried out by scanning electron microscopy (SEM) observations and by X-ray powder diffraction analysis (XRPD). Open porosity was calculated by He-pycnometer. Water absorption was measured by immersion test. Ageing tests, wet-dry and salt crystallization tests, were performed to study the decay phenomena. From the mineralogical analysis, a substantial difference was found out between the NYT on one side, and CI and PI on the other. The matrix of the former is mainly constituted by zeolites, amorphous phases, and volcanic glass; and the latter (CI and PI) have a matrix constituted by feldspars and minor amount of glass. The chapter provides table to illustrate variation of the physico-mechanical properties (porosity, water absorption, and uniaxial compressive strength) after aging tests. The overall results obtained show poorer durability of Neapolitan Yellow Tuff, when compared to other stones.