Investigation of the deterioration mechanisms induced by moisture and soluble salts in the necropolis of Porta Nocera, Pompeii (Italy)

Abstract This paper focuses on the diagnosis of damage processes decorative Roman renders a group tombs in Porta Nocera necropolis ancient city Pompeii, Italy. Unprotected from various climatic events, keep deteriorating since they were first excavated 1954. Extensive on-site and laboratory diagnostics using non-destructive low-destructive techniques have been able to demonstrate that soluble salts are among major agents deterioration, causing form render delamination. Gypsum is formed surface materials by deposition sulfur dioxide, resulting reduced porosity hardening surface. Soluble nitrates chlorides penetrate tombs’ masonry ground transported through layers tend crystallize subsurface. The crystallization—dilution cycles cause mechanical pressures, leading progressive destruction renders. Past conservation strategies secure plasters shown only limited effectiveness. In light data collected regarding salt decay, authors propose new strategies, questioning systematic use grouts restoration mortars for treatments focusing preventive maintenance ensure long-term preservation surfaces tombs.