Search

tConsolidation treatment is a common practice in the field of conservation. However, when consideringcalcareous materials, there is a lack of efficient and durable consolidants.Colloidal dispersions of Ca(OH)2nanoparticles, commonly known as nanolimes, can effectively recoverthe superficial loss of cohesion. However, they do not always guarantee in-depth mass consolidation.The aim of this paper is to give directions for improving in-depth deposition of nanolime dispersionswhen applied on limestone. A conceptual model, correlating the drying rate and the kinetic stability ofnanolimes dispersed in different solvents, to the porosity of the limestone to be treated, is conceived.This model can help to select a suitable nanolime solvent depending on the substrate.Nanolimes were synthetized and dispersed in different solvents (ethanol, isopropanol, butanol andwater). The morphology and size of the lime nanoparticles were studied by dynamic light scattering(DLS) and scanning electron microscopy (SEM-EDS). The kinetic stability of the nanolime was assessed byUv–vis spectroscopy. The porosity of the limestones were determined by mercury intrusion porosimetry(MIP), measuring as well their moisture transport properties.

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

An important operation for the conservation of historical renders is the cohesion restitution of the binderaggregate system, based on the use of materials with consolidating properties. Inorganic consolidants are usually preferred to organic ones due to better compatibility and durability. The aim of this work is the experimental characterization of two nanostructured consolidant products; a commercial nanolime, optimized with the addition of a reduced concentration of ethyl silicate, and a commercial nanosilica product underwent experiments to verify their consolidation efficiency. Nanostructured lime-based and silica-based products present interesting properties such as homogeneous distribution and high stability. Nanolimes were applied in combined applications with ethyl silicate, a well-known compatible product for consolidation intervention. The combined application guarantees some benefits and improves the mechanical and microstructural performance of these products. A nanosilica product was tested to better understand some known disadvantages (e.g. reduced penetration depth) and so its performances. Consolidant products were applied on weak lime mortar samples (prismatic samples and single mortar layer applied on bricks); these mortars were optimized by studying different binder-aggregate ratios, to simulate old lime mortar with cohesion loss. Consolidation effects were periodically evaluated to understand the treatments efficacy. Physicalmechanical characterization was performed on treated mortar samples, analysing superficial hardness and compressive and flexural strength. Microstructural observations and X-ray microanalyses of the consolidation products and of the consolidated mortar samples are also reported.

An important operation for the conservation of historical renders is the cohesion restitution of the binderaggregate system, based on the use of materials with consolidating properties. Inorganic consolidants are usually preferred to organic ones due to better compatibility and durability. The aim of this work is the experimental characterization of two nanostructured consolidant products; a commercial nanolime, optimized with the addition of a reduced concentration of ethyl silicate, and a commercial nanosilica product underwent experiments to verify their consolidation efficiency. Nanostructured lime-based and silica-based products present interesting properties such as homogeneous distribution and high stability. Nanolimes were applied in combined applications with ethyl silicate, a well-known compatible product for consolidation intervention. The combined application guarantees some benefits and improves the mechanical and microstructural performance of these products. A nanosilica product was tested to better understand some known disadvantages (e.g. reduced penetration depth) and so its performances. Consolidant products were applied on weak lime mortar samples (prismatic samples and single mortar layer applied on bricks); these mortars were optimized by studying different binder-aggregate ratios, to simulate old lime mortar with cohesion loss. Consolidation effects were periodically evaluated to understand the treatments efficacy. Physicalmechanical characterization was performed on treated mortar samples, analysing superficial hardness and compressive and flexural strength. Microstructural observations and X-ray microanalyses of the consolidation products and of the consolidated mortar samples are also reported.

Submitted by António Santos Silva (ssilva@lnec.pt) on 2013-08-21T14:02:52Z No. of bitstreams: 1 Borsoi et al_abstract.pdf: 32159 bytes, checksum: e2707ff0ae54e41464f60eda214fb57a (MD5) Rejected by arlindo@lnec.pt(arlindo@lnec.pt), reason: Acrescentar nas palavras chave nanoparticles ou equivalente on 2013-08-21T15:01:31Z (GMT) Submitted by António Santos Silva (ssilva@lnec.pt) on 2013-08-21T15:11:06Z No. of bitstreams: 1 Borsoi et al_abstract.pdf: 32159 bytes, checksum: e2707ff0ae54e41464f60eda214fb57a (MD5) Approved for entry into archive by arlindo@lnec.pt(arlindo@lnec.pt) on 2013-08-21T15:12:30Z (GMT) No. of bitstreams: 1 Borsoi et al_abstract.pdf: 32159 bytes, checksum: e2707ff0ae54e41464f60eda214fb57a (MD5) Made available in DSpace on 2013-08-21T15:12:30Z (GMT). No. of bitstreams: 1 Borsoi et al_abstract.pdf: 32159 bytes, checksum: e2707ff0ae54e41464f60eda214fb57a (MD5) Previous issue date: 2013 Made available in DSpace on 2014-10-20T16:31:38Z (GMT). No. of bitstreams: 2 license.txt: 1838 bytes, checksum: 72647f70fb80bcf8438465294cbf7587 (MD5) Borsoi et al_abstract.pdf: 32159 bytes, checksum: e2707ff0ae54e41464f60eda214fb57a (MD5) Previous issue date: 2013 Made available in DSpace on 2017-04-13T10:30:52Z (GMT). No. of bitstreams: 2 Borsoi et al_abstract.pdf: 32159 bytes, checksum: e2707ff0ae54e41464f60eda214fb57a (MD5) license.txt: 1838 bytes, checksum: 72647f70fb80bcf8438465294cbf7587 (MD5) Previous issue date: 2013 This study was developed within a Project (Limencontech - Conservation and durability of historical renders: compatible techniques and materials) financed by FCT – Fundação para a Ciência e a Tecnologia (Portugal); special thanks goes to Paula Menezes for SEM-EDS analysis and to Bento Sabala and Ana Maria Duarte for mechanical tests. 4 2 942-947pp Vols. 730-732 DM/NMM Materials Science Forum

This work is inserted in a wider project aiming at the conservation and durability of historical renders, through compatible techniques and materials; in particular the restitution of cohesion of historical renders is studied. Surface consolidation, directed to restore cohesion and stability, is based on the use of materials with aggregating properties. This operation is reached usually through the use of inorganic or mineral consolidants, which are preferred to organic ones, due to better compatibility and durability. Based on the results of previous studies, two mineral compatible products were selected: a commercial dispersion of nanoparticles of calcium hydroxide in propanol and a calcium-silicate product, consisting on a limewater dispersion of ethyl silicate. Consolidation products were applied on mortar specimens (mortar prisms and mortars applied on bricks) in order to assess their efficacy by determining their microstructural and physical-mechanical properties, before and after consolidation treatment. A low binder ratio mortar was studied with both consolidants. Microstructural (optical and SEM microscopy) and chemical analysis of the consolidation products and of the consolidated samples were performed; physical-mechanical analysis, namely superficial hardness is reported. DED/NRI 2011 14-18 Junho 2011

3rd Historic Mortars Conference, 11-14 September 2013, Glasgow, Scotland The consolidation process of old renders with loss of cohesion is nowadays performed usually with inorganic compatible products, such as calcium or barium hydroxide or ethyl silicate. The use of organic consolidants as acrylic or vinilic resins is discouraged due to its physico-chemical incompatibility with the original lime-based renders; these organic products work as adhesive in the original substrate, while inorganic consolidants contribute to recover the cohesion loss improving the binder amount and guarantying better durability and full compatibility.The restoration intervention on historic mortars, including consolidation, often causes aesthetic heterogeneity and prejudices, sometimes dramatically, the global legibility of the architectonic surface. The aesthetic function can be restored by chromatic reintegration, through several techniques, with resource to overpaints, for instance based on calcium hydroxide, pigments and silicates.In this study several consolidant lime-based products were produced and characterized. Pigments were added to the products, in order to achieve chromatic reintegration properties as well as consolidation. The consolidant products consist in aqueous dispersion of calcium hydroxide, a pozzolanic additive (metakaolin or diatomite) and mineral pigments, namely a yellow earth pigment and a synthetic red pigment. The incorporation of a pozzolanic material was made to improve the mechanical strength and durability of the binder.The consolidant products were applied on mortar specimen with a simulated cohesion loss, through a reduced binder quantity and an optimization of the aggregate grain size. Specimens were subjected to different storage conditions (50 and 95% RH), to verify the influence of curing conditions. Physico-mechanical and microstructural characterization was performed on the treated mortar specimens to verify the consolidant treatment efficacy. Consolidant treatments show intesting results, and their efficacy vary depending on the pozolanic addition; pigments do not influence that much the consolidation efficiency.