New nanomaterials for consolidating stone
Physical chemistry experiments focused on the efficacy of consolidating treatments have been carried out with lime particles (chemical species: calcium hydroxide—Ca(OH)) both in laboratory and in hypogeum environment (catacomb), in order to understand the influence of different microclimatic conditions and to deduce the best nanolime suspension concentration by measuring the microstructure and chemical composition of stone materials differently treated.The samples examined in the present research come from different materials: laboratory-made samples and stone samples coming from hypogeum environment such as funerary inscriptions fragments.This work grows out from the need to develop consolidating treatments tailored for a specific archaeological structure  under hypogeal conditions .Generically in a preventive conservation project, treatments and materials are always more frequently evaluated in order to provide two main requisites:highest durability, through the combination of complementary preventive activities, such as monitoring and adjusting environmental parameters and defining a monitoring and routine maintenance plan of the structures, together with graphic and photographic documentation, and the systematic data archiving, in order to easily compare the short-run and the long-run variations.More in detail, it has been chosen to work with different isopropyl alcohol suspension in different times in order to evaluate the efficacy of the dispersion used in the consolidation treatment, the penetration depth of the consolidating product, and the possible chromatic alterations.The final aim has been to choose the optimal suspension for consolidating treatments of historical specimen and inscriptions.
In all, eight samples contained red-ochre pigment and the other eight contained cinnabar pigment (Hg S); four cinnabar samples and four red-ochre samples have been treated in laboratory while the other eight in the catacombs.
Nanotechnologies and nanolime, as consolidating materials for architectural and stone surfaces , have been developed mainly in the last years, for the capability to solve several problems connected with conventional lime treatments, such as incomplete lime carbonation process, limited depth penetration, and the formation of thin white superficial layers .
The materials in nanodimensions have specific chemical and physical properties, linked to the physical and chemistry properties of very small particles with respect to the massive materials .
This involves a series of partially unsolved problems, concerning the products used for deteriorated structures consolidation.
The choice of materials depends on several factors such as: microclimatic conditions, application methods, and reaction time of products.