ELARCH Project: the use of innovative product based on nanotechnologies for the protection of architectural heritage

Most of the world's architectural heritage consists of constructions in stone materials. These materials conditioned to the architectural styles of the past and marked connotative characters of entire ancient cities. There is a huge variety of stone materials that have substantially different characteristics depending on the type of sourced rocks from which they are extracted. Limestone rocks of biochemical origin are widespread in all over the countries both of Latin America and Mediterranean area, where they are often known with the local denominations, such as calcarenites or tuffs of Matera, Lecce, Agrigento, Malta, etc. These materials are affected by synergistic chemical, physical and biological degradation phenomena caused by the complex interaction between the materials and the environment that surrounds them, i.e. exposure environment. The degradation of materials can compromise the structural behavior of the construction, increasing its seismic vulnerability. The preservation of the architectural heritage built with stone materials requires restoration works able to neutralize or, at least, to reduce the degradation phenomena of these extremely vulnerable materials. The choice of the consolidating and protective products plays a key role in the effectiveness of restorations: their wrong choice can determine the uselessness of restoration works, but it can also worsen the diseases of the stones and irreparably damage architectural heritage. However, the effectiveness of these products is highly dependent on the stone characteristics and on the many interactions that occur among the stone, the product and the exposure environment over the short and long time after the restoration treatment. This paper illustrates a multidisciplinary research activity on the use of innovative product based on lime and nanoparticles of graphene in restoration and seismic retrofit of masonry constructions in limestone materials. The use of graphene as nanotechnological component overcomes the drawbacks of traditional products based on lime, providing extraordinary physical properties (hardness, strength and flexibility) to the investigated product. This is translated to more durability, less maintenance costs of the repair and restoration works.