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tNovel nanomaterials, such as nanosilica or nano-titanium oxide, have been developed in the last decadefor the conservation of the built heritage. Among nanomaterials, nanolimes have acquired a considerablerelevance due to their potentialities as consolidant product. The so-called nanolimes, colloidal disper-sions of calcium hydroxide nanoparticles in alcohols, have been successfully applied as pre-consolidantson frescos and paper, and their use has later been extended to plasters, renders and stone. Nanolimeshave better potentialities compared to conventional inorganic consolidants based on limewater (e.g.faster carbonation rate and higher calcium hydroxide concentration). Moreover, nanolimes are consid-ered more compatible with CaCO3-based substrates than alkoxysilanes (e.g. TEOS), the most widely usedconsolidant products. Nanolimes can guarantee the recovery of the superficial cohesion of degradedmaterials. However, when a mass consolidation is required, like in the case of decayed stone, nanolimesshow some limitations. One of the problems is caused by nanolime accumulation at or just beneath thesurface of the treated material. In order to solve this problem, the transport mechanism of nanolimewithin porous materials, as stone or renders, should first be better understood. Commercial nanolimeswere applied on Maastricht limestone, a high-porosity yellowish limestone, used in the Netherlands andBelgium as traditional building material. The absorption and drying behaviour of nanolime in this lime-stone was measured and nanolime deposition in the stone was studied by optical and scanning electronmicroscopy. The results show that nanolime transport is strictly related to the properties of the solvent.The alcoholic solvent guarantees a stable dispersion that penetrates in depth in the material, but is par-tially back-transported to surface. The high volatility of the solvent and the high stability of the dispersionfavour the partial back-migration of lime nanoparticles to the surface during drying

The development of nanomaterials is growing exponentially in the last decade. New discoveries and their applications have taken place in different fields, such as electronics, chemistry, biology and physics. Some innovative nanoproducts have become available also for the conservation of cultural heritage (e.g. nano-Ca(OH)2, nano-SiO2, nano-TiO2, CNTs, etc.), showing interesting potentialities and advantages. However, there are also drawbacks. Extensive literature is available on nanolimes, i.e. colloidal alcoholic dispersions of Ca(OH)2 nanoparticles, which are promising materials for the consolidation of lime-based plasters and calcareous stone, often present in ancient masonry structures. Nanolimes have several advantages such as high stability, fast carbonation rate and good chemical and physical compatibility with calcareous stone and lime-based plasters. However, in comparison to other existing consolidant products, like TEOS-based (Tetraethylorthosilicate), the penetration depth of nanolime is often limited, which may consequently result in a low effectiveness. The research presented in this paper aimed at understanding the penetration and deposition process of nanolime when applied in Maastricht limestone, a soft, highly porous substrate, widely used in the Dutch and Belgian provinces of Limburg. This research focused on the nanolime transport process to clarify whether nanolime is able to penetrate and deposit in depth in the material or if it simply accumulates near the surface. In order to investigate the distribution and particle size of nanolime deposited in the stone, next to simple phenolphthalein tests, optical microscopy, AFM and SEM-EDS were used. On the basis of the obtained results, the transport and deposition of a commercial nanolime in Maastricht limestone has been elucidated. The comprehension of the nanolime transport mechanism (penetration and distribution) within the treated material is crucial for improving the effectiveness of this consolidation treatment.

The development of nanomaterials is growing exponentially in the last decade. New discoveries and their applications have taken place in different fields, such as electronics, chemistry, biology and physics. Some innovative nanoproducts have become available also for the conservation of cultural heritage (e.g. nano-Ca(OH)2, nano-SiO2, nano-TiO2, CNTs, etc.), showing interesting potentialities and advantages. However, there are also drawbacks. Extensive literature is available on nanolimes, i.e. colloidal alcoholic dispersions of Ca(OH)2 nanoparticles, which are promising materials for the consolidation of lime-based plasters and calcareous stone, often present in ancient masonry structures. Nanolimes have several advantages such as high stability, fast carbonation rate and good chemical and physical compatibility with calcareous stone and lime-based plasters. However, in comparison to other existing consolidant products, like TEOS-based (Tetraethylorthosilicate), the penetration depth of nanolime is often limited, which may consequently result in a low effectiveness. The research presented in this paper aimed at understanding the penetration and deposition process of nanolime when applied in Maastricht limestone, a soft, highly porous substrate, widely used in the Dutch and Belgian provinces of Limburg. This research focused on the nanolime transport process to clarify whether nanolime is able to penetrate and deposit in depth in the material or if it simply accumulates near the surface. In order to investigate the distribution and particle size of nanolime deposited in the stone, next to simple phenolphthalein tests, optical microscopy, AFM and SEM-EDS were used. On the basis of the obtained results, the transport and deposition of a commercial nanolime in Maastricht limestone has been elucidated. The comprehension of the nanolime transport mechanism (penetration and distribution) within the treated material is crucial for improving the effectiveness of this consolidation treatment.

The development of nanomaterials is growing exponentially in the last decade. New discoveries and their applications have taken place in different fields, such as electronics, chemistry, biology and physics. Some innovative nanoproducts have become available also for the conservation of cultural heritage (e.g. nano-Ca(OH)2, nano-SiO2, nano-TiO2, CNTs, etc.), showing interesting potentialities and advantages. However, there are also drawbacks. Extensive literature is available on nanolimes, i.e. colloidal alcoholic dispersions of Ca(OH)2 nanoparticles, which are promising materials for the consolidation of lime-based plasters and calcareous stone, often present in ancient masonry structures. Nanolimes have several advantages such as high stability, fast carbonation rate and good chemical and physical compatibility with calcareous stone and lime-based plasters. However, in comparison to other existing consolidant products, like TEOS-based (Tetraethylorthosilicate), the penetration depth of nanolime is often limited, which may consequently result in a low effectiveness. The research presented in this paper aimed at understanding the penetration and deposition process of nanolime when applied in Maastricht limestone, a soft, highly porous substrate, widely used in the Dutch and Belgian provinces of Limburg. This research focused on the nanolime transport process to clarify whether nanolime is able to penetrate and deposit in depth in the material or if it simply accumulates near the surface. In order to investigate the distribution and particle size of nanolime deposited in the stone, next to simple phenolphthalein tests, optical microscopy, AFM and SEM-EDS were used. On the basis of the obtained results, the transport and deposition of a commercial nanolime in Maastricht limestone has been elucidated. The comprehension of the nanolime transport mechanism (penetration and distribution) within the treated material is crucial for improving the effectiveness of this consolidation treatment