The potentialities of nanomaterials for application in the field of conservation have been widely investigated in the last two decades. Among nanomaterials, nanolimes, i.e., dispersions of lime nanoparticles in alcohols are promising consolidating products for calcareous materials. Nanolimes are effective in recovering the very superficial loss of cohesion of decayed materials, but they do not always provide sufficient mass consolidation. This limitation is mainly related to the deposition of the nanoparticles nearby the surface of the material. Experimental research has been set up with the aim of improving the in-depth deposition of lime nanoparticles. Previous research by the authors has shown that nanolime deposition within a substrate can be controlled by adapting the nanolimes properties (kinetic stability and evaporation rate) to the moisture transport behavior of the substrate. Nanolime properties can be modified by the use of different solvents. In this research, nanolime dispersions have been further optimized for application on Maastricht limestone, a coarse porous limestone. Firstly, nanolimes were synthesized and dispersed in ethanol and/or water, both pure and mixed in different percentages. Subsequently, based on the kinetic stability of the nanolime dispersions, the most promising solvent mixtures were selected and applied on the limestone. The deposition of lime nanoparticles within the limestone was studied by phenolphthalein test, optical microscopy and scanning electron microscopy. The results confirm that nanolime dispersed in a mixture of ethanol (95 %) and water (5 %) can guarantee a better nanoparticles in-depth deposition within coarse porous substrates, when compared to dispersions in pure ethanol.

Over the past two decades, the application of nanostructured materials in construction, such as concrete, paint, coatings, glass, renders, plasters, thermal insulation, steel, and even sensors, has become increasingly prevalent. However, previous studies and reports have raised concerns about the ecotoxicity and long-term impact of nanomaterials on human health and the environment. National and international legislation and regulations are struggling to keep up with the rapid development of nanomaterials, taking into account their unique characteristics and essential requirements for application and commercialization. This paper, based on existing standards for conventional materials and bibliometric networks of papers focused on nanomaterials, conducts a critical review and proposes relevant indicators for the application of nanomaterials in the construction sector. These indicators should be mandatory and are divided into environmental, human health, and economic perspectives, providing a risk assessment framework for applying nanomaterial-based constructive solutions oriented to environmental, social, and economic sustainability.