Nuovi nanomateriali per applicazioni nella conservazione e consolidamento di beni in pietra, di interesse artistico-culturale in Albania.

Responsabili di progetto

Dritan Siliqi, Bujar Dida

Accordo

ALBANIA - MoES - Ministry of Education and Sport of the Republic of Albania

Bando

CNR/MOES biennio 2018-2019 2018-2019

Dipartimento

Scienze chimiche e tecnologie dei materiali

Area tematica

Scienze chimiche e tecnologie dei materiali

Stato del progetto

Nuovo

Proposta di ricerca

In recent times, nanomaterials have been applied in the construction and maintenance of the world cultural heritage with the aim of improving the consolidation and protection treatments of damaged stone. These nanomaterials include important advantages that could solve many problems found in the traditional interventions. The basic principle of the patrimony is that the cultural heritage is an incalculable and integral legacy to our future. The obligation to preserve and provide access to it is an absolute necessity. Nowadays, it warns a growing concern for the situation that the degradation of this rich and fragile heritage has reached. In addition, conservation of stone heritage is always a delicate and complex challenge. Multiple variables have to be taken into account to identify the problems, define the necessary conservation actions and to select materials and procedures to be used. The variety of factors to be analyzed includes the intrinsic stone properties, the state of conservation, the degradation mechanisms and the environmental factors. Thus, it is necessary to select the appropriate materials and procedures for a correct conservation treatment. Compatibility, depth of penetration, durability, effect on liquid water and vapor permeability, in addition to biological resistance, application method, or health matters are important factors to take into account. While the development in material science has generated important nanostructured materials long time ago, conservation of cultural heritage has been, until recently, mainly based on the traditional conservation and restoration treatments. These traditional methods, such as the use of synthetic polymers, often lack the vital compatibility with the original substrate and a durable performance. More recently, nanomaterials are being applied in the construction and maintenance of the architectural heritage with the aim of improving the consolidation and protection treatments of damaged building materials. Consolidation is one of the most important conservation treatments carried out on stone heritage. The application of nanotechnology in the cultural heritage conservation is marked by the possibility to design consolidant products highly compatible with the original stone substrate. Moreover, when particles have dimensions of about 1-100 nanometers, the material properties change significantly from those at larger scales. The nanoparticles must have the following attributes: stability and sustained photoactivity, biological and chemical inactivity, non-toxicity, low cost, suitability towards visible or near UV light, high conversion efficiency and high quantum yield, could be react with wide range of substrate and high adaptability to various environment and good adsorption in solar spectrum. In addition, these treatments can also have water repellent properties which favor this self-cleaning action, and prevent the generation of damage caused by water. The most commonly used inorganic consolidants are the products based on hydroxide nanoparticles due to their compatibility with a large part of the built and sculptural heritage. Calcium hydroxide (also known as lime wash putty) is one of the oldest products used in construction, mainly as a binder in mortars (joint mortars, renderings, wall fillings, etc), in mural paintings, as a consolidant product, together with other materials such as rammed-earth. It can be used to restore the cohesion loss by filling the porosity of calcareous stones (limestones, marbles, and mortars). Another material should be strontium hydroxide NPs. The synthesis of them are obtained by bottom-up approach, and their use as consolidant products and also as a de-sulphating agents for stone, mortars and wall paintings are proposed. Another nanomaterial is Hydroxyapatite (HAP) used for carbonate stone consolidation. HAP can be applied for the consolidation of limestones , marbles, and sandstones with different carbonate contents. This product is not introduced directly into stone material, but is formed by the reaction between phosphate ions coming from an aqueous solution of di-ammonium hydrogen phosphate (DAP) applied to the stone and calcium ions coming from substrate. Among its advantages, HAP has shown a good compatibility with the crystal structure and lattice parameters of calcite. Thanks to its low viscosity, this aqueous consolidant product is able to penetrate deeply into the stone, generating a significant improvement in mechanical properties. The HAP has been tested as a protective treatment for marble against acid rain corrosion. The study of compatibility and adaptability requires that the physical-chemical properties of both consolidant products and stone substrate are well known. Such a knowledge plays a very important role for the good outcome of the present project. Materials of interest will be analysed by using not-destructive techniques such as X-ray diffraction which is effective on crystalline materials and is able to carry out information on chemical composition, size, shape and atomic structure. In particular, powder X-ray diffraction technique can be used on natural and synthetic samples which are available in the micro- and/or nano- crystalline form. A depth investigation of physical-chemical properties and their variation with the environmental conditions can be obtained analyzing diffraction data collected at room and at variable temperature. Recently, with the groups in Albanian as partner, we presented a project (SINCHRA, 1.2 milion euro) in the framework of the program INTERREG IPA CBC ITALY-ALBANIA-MONTENEGRO (successfully superating the first step of evaluation). As well the italian coordinator (with the support of CNR) was promotor of the fondation of the Association of Albanian Crystallographers, recently become member of the European Crystallographic Association (ECA) and of the International Union of Crystallography (IUCr).

Obiettivi della ricerca

Piloting tests (IC-CNR) of preparation on nanomaterials (NPs) of Ca(OH)2, Sr(OH2) and HAP, proving guidelines for the laboratory preparation (PUT, Albania) by identification of the best conditions and procedures.
Characterization of above NPs to obtain parameters like the composition and size distribution by using XRPD, SAXS, DLS and SEM (IC-CNR, PUT)
Materials of interest from Culture Heritage, to to be protected/consolidated and/or restored, (selected by Albanian Team, PUT) will be analyzed by using not-destructive techniques such as X-ray diffraction, which is effective on crystalline materials and is able to carry out information on chemical composition, size, shape and atomic structure. In particular, powder X-ray diffraction technique can be used on natural and synthetic samples which are available in the micro- and/or nano- crystalline form. A deep investigation of physical-chemical properties and their variation with the environmental conditions can be obtained analyzing diffraction data collected at room and at variable temperature.
Test in the laboratory (PUT, Albania) of the obtained NPs on the materials similar to the natural ones (marble, limestone etc) at different controlled conditions of humidity, temperature and Co2.
Publication of the results at the national/international reviews of the sector and their presentations at the dedication national/international conferences/meetings.

Ultimo aggiornamento: 12/12/2024