Salt Crystallization in Porous Materials : Physicochemical Aspects and Effects of Anti-Scaling Additives.

Abstract

Investigates the mechanism of crystal growth of some inorganic within porous substrates, in order to explain the processes of alteration of the porous material surfaces in architectural and artistic conservation. In particular, attention focused on salt crystallization in the presence of some organo-aza-phosphonate compounds, additives known as anti-scaling agents, able to prevent and/or inhibit nucleation and growth of solid phases from saturated and supersaturated salty solutions. The applicative goal was to understand how the action of these additives could represent an innovative methodology in the field of preventive conservation, in order to reduce and limit the damages on monuments, historical buildings, and mural paintings deriving from the presence of crystallization/solubilization cycles. The experimental study was carried out by investigating the physical-structural properties, namely porosity, and the changes in morphology (by SEM and ESEM) due to salt crystallization (KNO3 and Na2SO4) within porous materials of artistic or architectonic interest (stones, aerial mortars) and the effect of the anti-scaling additives in minimizing damage on porous materials.