Search

Roughness, pigment impurities, and neoformed minerals are important factors affecting the reflectance of painted surfaces. However, other factors that have not yet been studied in detail, such as the total thickness of the paint layer and the amount of binder, should also be considered. In this research, oil painting mock-ups, each made with a different number of layers of paint containing a single pigment (lead white, orpiment, cinnabar, azurite or malachite) mixed with different proportions of oil binder, were examined using a hyperspectral imaging system. The results indicate that these characteristics do not directly influence the reflectance of the painted surface. Interestingly, we found that the distribution of the pigments and the oil binder in the paint system (and pigment-binder interaction) are also key to understanding the reflectance values. Thus, accumulation of oil on top of the uppermost paint layer in the multilayer painting mock-ups caused a reduction in reflectance. The increased translucency of the oil paint containing lead white pigment also modified the reflectance, possibly due to the formation of metal soap. Other factors found to affect the reflectance of the painting mock-ups are discussed. Universidade de Vigo | Ref. CINTECX Universidad de Granada | Ref. RMN-179 Ministerio de Ciencia e Innovación | Ref. RYC2020-028902-I

Gypsum black crust is one of the most severe deterioration forms affecting the built Cultural Heritage (CH) worldwide. Its removal from granitic substrates is necessary since gypsum layer favours the deterioration of the rock. This study investigates the laser assisted removal of gypsum black crust, from a Hercynian granite from the North-West (NW) Iberian Peninsula. The suggested laser cleaning methodology involves the combination of two wavelengths (1064 nm and 355 nm) from a QS Nd:YAG laser system and is based on their simultaneous interaction with the involved materials at various fluence values and FIR/FUV ratios (1/1, 1/3 and 3/1). This ablative scheme was initially introduced in order to overcome undesirable discoloration issues recorded upon single wavelength laser cleaning of black crusts but its role to effectively remove different undesired over-layers was also acknowledged. The results of this study were comparatively evaluated with surfaces irradiated using one of the two specific wavelengths, while the presence of water as an enhancing cleaning agent was also considered. A multi-analytical evaluation methodology based on stereomicroscopy, Raman spectroscopy, Fourier Transform Infrared spectroscopy (FTIR) and Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDS), was carried out to determine the optimum cleaning strategy in terms of crust removal effectiveness and minimisation of damages to the substrate. The optimum irradiation condition determined in this study is the simultaneous application of the two wavelengths in FIR/FUV = 1/1 ratio (with FIR = FUV = 0.3 J·cm−2) on a pre-wetted surface. Under this irradiation condition a high removal level of carbonaceous pollution particles and gypsum was achieved, without any damage to the granitic minerals in the form of melting and spallation and/or exfoliation of planes of biotite and K-feldspar and cleavage fracture of quartz.

The use of adhesives to repair stone is a common conservation and restoration practice. Thermoplastic (acrylic) and thermostable (epoxy, polyester, etc) adhesives are often combined to take advantage of the benefits of both types. An intervention layer in the form of an acrylic adhesive is typically previously applied to enhance the reversibility of the structural adhesive used. However, research into the mechanical strength of the bonded stone and into the harmful effects of different adhesives on stone is scarce and is even non-existent for granites. We evaluate the effectiveness, harmful effects and reversibility of the structural adhesives Araldite AY 103-1 (epoxy resin) and Fluoline A (acrylic resin) applied with and without a previous intervention layer of Paraloid B-72, and with and without the addition of micronized silica to the structural adhesives (a common practice among restorers to change the mechanical properties of the adhesives and enhance the reversibility). We used a multi-analytical approach based on assessing shear strength of adhesive bond, water absorption by capillarity, water vapour permeability, colour, stereomicroscopy and scanning electron microscopy. Araldite with a Paraloid intervention layer, both with and without silica, proved to have the best adhesive capacity. However, failure tended to occur in the rock rather that at the join. The Paraloid B-72 intervention layer, while it enhanced reversibility, also acted as a barrier to water transport. The micronized silica enhanced both the hydric properties of the stone and the reversibility of adhesive application. Fluoline had the best reversibility profile. These findings should prove useful in informing granite-built cultural heritage interventions.

Correctly describing the deterioration patterns is of great importance for the conservation of built cultural heritage. Also, their rapid in situ quantification is an essential requisite when studying exposed stone objects, to define satisfactory restoration actions and to avoid greater damage due to the application of incorrect treatments. The research described in this paper targets developing a methodology to compute the extent of different deterioration patterns on a granitic cultural heritage object using as a case study an overpass bridge called Puente Nuevo in Ourense (NW Spain). The applied methodology consisted of the combination of the geometric and radiometric information collected from a non-invasive and in situ mobile LiDAR system (MLS) and micro destructive analytical techniques. Laser scanning points were used as a base to create orthophotos, being their intensity values the input for an unsupervised classification method to determine the areas occupied for those different deterioration patterns. In parallel, as part of this multi-analytical approach different conventional analytical techniques (X ray diffraction, Fourier transform infrared spectroscopy and optical microscopy) were applied to chemically and mineralogically characterize those deterioration patterns, namely, gypsum black crust, calcite encrustations and biological colonization (mosses). LiDAR technology allowed to determine three different clusters considering the reflectance of those surfaces: uncoated granite, calcite encrustations and black crusts and biological colonization patinas in a combined cluster due to their close reflectance spectra. The computed extent and the location of those deterioration patterns will allow to identify the most suitable cleaning treatment saving money and time.

This paper shows a study on the consolidation effectiveness of nano-silica and nano-lime-based consolidants (i.e. Nano Estel®and Nanorestore®, respectively), both available on the market, on two stones with different mineralogy and texture (i.e. two micas granite and Lioz limestone) previously subjected to 500 °C during 24 h with a rapid cooling by water jet simulating the real practice in a fire. The consolidation effectiveness was determined through the evaluation of hydro-physical properties (i.e. open porosity, apparent density, water absorption by capillarity and water absorption at atmospheric pressure), the determination of P-wave velocity (compressional wave velocity) and the study of their side-effects by using stereomicroscopy, colour spectrophotometry, Fourier transform infrared spectroscopy and scanning electron microscopy. Durability of the consolidants was determined by measuring their resistance to salt crystallization cycles and the subsequent surfaces were evaluated by open porosity measurements, stereomicroscopy, Fourier transform infrared spectroscopy and scanning electron microscopy. Results showed, as expected, that both granite and limestone samples increased their porosity after the heating process. In the case of granite stone, both products yielded similar reduction of the porosity and similar resistance to salt crystallization cycles. In case of limestone, nanolime samples yielded lower effectiveness in terms of dry matter, porosity and water absorption by capillary coefficient, which is attributed to the low penetration of Nanorestore® particles in the fine pore structure of this stone. Ethyl silicate treated samples presented higher levels of decay after crystallization cycles in the limestone samples, which could be attributed to the difficulty to bond silicate materials to fine porous calcite-based substrates.

[EN] Microorganisms that can act as biocleaning agents can potentially be isolated from existing graffiti. In this study, a total of 30 different isolates of bacteria, fungi and yeasts were obtained from black, blue, red and silver graffiti coatings exposed outdoors conditions for 10 years. An additional strain was obtained from samples of black powdered graffiti exposed under laboratory conditions for 5 years. Each of the isolates from the most prolific sources (i.e. red and silver graffiti coatings and black powdered graffiti) was evaluated alone and in combination with Tween? 20, to determine their potential as biocleaning agents, in test tube assays. Two strains isolated from the red graffiti coating (identified as Candida parapsilosis) and one strain isolated from the black powered graffiti (identified as Rhodococcus erythropolis) performed best alone. The quantity of live cells throughout the trials and biofilm formation indicated that both strains were able to utilize the paint as a substrate. When the microorganisms isolated were combined with Tween? 20, the quantity of live cells increased notably throughout the incubation time, and turbidity and graffiti discoloration were observed. Infrared spectroscopic examination revealed that R. erythropolis performed the best alone, while the addition of Tween? 20 to C. parapsilosis enhanced the oxidative degradation of the graffiti., J.S. Pozo-Antonio is grateful to the Spanish Ministry of Economy and Competitiveness (MINECO) for a post-doctoral contract (Juan de la Cierva-Incorporacion, IJCI-2017-3277). P. Sanmartin is grateful for financial support from the Xunta de Galicia (grant ED431C 2018/32).

The effects of the four common commercial finishes (polished, honed, disc cutting and bush hammering) on several properties of ornamental granites were evaluated. Two granites of different texture, widely used as ornamental stones in NW Iberian Peninsula, were selected. Roughness, colour and reflectance (properties used as cleaning indicators of cultural heritage objects) of the surfaces subjected to each finish were characterized and the correlations among these parameters were obtained. The results show that the roughness generated by disk cutting and polishing is higher in Vilachan than in Rosa Porrino, showing that the finer the grain size, the higher the roughness generated. The lightness parameter (L∗) in CIELAB space is dependent on the roughness of the surface. The rest of the colour parameters (a∗, b∗, C∗ab and hab) does not depend on roughness and they are related mostly with the colour of the surface by itself. Reflectance features are not affected by the different content of forming minerals and superficial colour which condition the reflectance intensity of each commercial finish. Reflectance is directly related with the roughness of the granite; the rougher the surface the higher the reflectance intensity. In addition, the lightness L∗ and the reflectance are directly related while the other colour parameters do not show any relation with the reflectance. These results can be used as an aesthetical criteria in order to standardize an objective methodology to evaluate the cleaning effectiveness in the conservation of cultural heritage objects.

This paper addresses the evaluation of the cleaning of crustose lichens developing on granite. The evaluation was performed considering the effectiveness of the cleanings and harmfulness exerted on the granite. The laser cleaning of lichen was compared with the most conventional procedure, scalpel. The combination of both procedures was also tested. The study, which was carried out with two different species of crustose lichen, was also focused on the influence of the intrinsic characteristics of the lichen on the effectiveness. The cleanings were evaluated by optic and electronic microscopies, FTIR and colour spectrophotometry. A previous characterization of the lichen and its interaction with the granite using those analytical techniques were also performed. The laser cleaning effectiveness depends on the coverage and the colour of the lichen; also, the prior mechanical weakening of the lichen by scalpel seemed to improve the laser cleaning. The darkest lichen was satisfactorily removed by laser and with the combined cleaning. Conversely, the lightest lichen was more difficult to extract with laser than the darkest lichen, being necessary to apply both methods sequentially. Despite laser and the combination of methods cleaned satisfactorily the surface, they were unable to eliminate the thalli into fissures.

Interferometric profilometry and hyperspectral imaging techniques combined with traditional analytical techniques such as spectrophotometry, stereomicroscopy, X-ray diffraction, scanning electron microscopy, particle size analysis, and thermogravimetry were used to characterize tempera paint mock-ups. These paint mock-ups were prepared as binary mixtures made by mixing either egg yolk or rabbit glue binders with one of ten pigments traditionally used by mediaeval artists, namely lime, calcium sulfate, white lead, minium, hematite, cinnabar, azurite, lapis lazuli, blue smalt and malachite. We evaluated the effects of mineralogical composition, pigment particle size and morphology, as well as the type and concentration of the binder on the physical properties of the paintś surface. Results showed that all the above compositional aspects had a direct influence on the paintś color, reflectance, and roughness. Moreover, mineral impurities and neoformed minerals due to pigment-binder interaction during paint preparation had a crucial effect on the superficial physical properties of paints. The analytical results proved the usefulness of interferometric profilometry and hyperspectral imaging techniques for the characterization of paint surfaces. The gained information will help conservation specialists in the evaluation of the impact of conservation treatments on the paint surface and the assessment of surface damage caused by weathering processes.

Marking petroglyphs with chalk is a common practice to enhance them for documentation and reproduction. Although this procedure has started to be less frequently used, there is no knowledge about the interaction between the rock engravings nor about the effectiveness achieved by the common cleaning procedures of such markers considering the chalk extraction and the induced damage to the rock. This study evaluates the interaction between two chalks of different composition (calcite and gypsum) and a granite on which the majority of NW Iberian Peninsula-petroglyphs are carved. Granitic samples marked with these chalks were subjected to artificial rain events and high temperatures (700 °C) related to fires. After each aging test, chemical and physical modifications on the rock were analysed by means of stereomicroscopy, x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and colour spectrophotometry. Moreover, the evaluation of the effectiveness and harmfulness of several mechanical and chemical cleaning procedures commonly used in the field of cultural heritage conservation was carried out. Both chalks remained at different extent on the surface after the artificial rain events. Water would promote a different penetration-depth of the chalks into the stone, depending on their solubility. High temperatures led to mineral phase transformations of the chalks influencing the interaction with the rock. Regarding cleaning effectiveness, despite a few chalk remains were found in all the cleanings, chemical methods showed higher effectiveness than mechanical procedures even though some of them leave chemical contamination. Benzalkonium chloride can be considered as the cleaner with the best results to extract both types of chalk on granite.

Lime-, cement- and lime & cement-based mortars, containing different proportions of nanocrystalline TiO2 (1, 2.5 and 5 wt%) and fine aggregates of silicate nature have been investigated with the aim to improve the knowledge in terms of their chemical, physical and mechanical properties. The influence on the physical-mechanical properties induced by the addition of TiO2 were evaluated through measurement of chromatic parameters, open porosity, water absorption coefficient at atmospheric pressure, P-wave velocity, material loss by peeling test and microdrilling resistance and compared to the reference mortars ones, i.e., without the TiO2 nanoparticles addition. Moreover, stereo and electronic microscopy were used to study the morphology, the mineralogical and chemical composition of each mortar formulation. Fourier transform infrared spectroscopy was also applied to gather qualitative information on the chemistry of some of the characteristic components of the mortar. The results suggest that the physical-mechanical properties of the studied mortars were influenced by the TiO2 nanoparticles addition. Furthermore the influence of the TiO2 on the properties of the studied mortars is also dependent on the nature of the binder used. Nevertheless, in general terms, the global colour change showed a direct relationship with the TiO2 content. Regarding the hygric properties, mortars with higher addition of TiO2 content showed higher open porosity and water absorption coefficients, but an exception for the cement-based mortar with 2.5 wt% was detected. The values obtained in the mechanical properties evaluated were inversely related with the hygric parameters.

The polymineralic characteristic of granite implies an additional challenge during the laser cleaning of cultural heritage built of this rock, because the forming-minerals experience different behaviours under the laser radiation, leading to damages of variable nature and intensity. The aim of this work was to identify the ranges of fluence to satisfactorily and safely clean the four main constituent minerals of granite (quartz, K-feldspar, plagioclase and biotite) painted with three different graffiti colours. The cleaning was performed using a nanosecond Nd:YVO 4 laser which works at high pulse rate (kilohertz). The evaluation of cleaning effectiveness was performed in terms of graffiti extraction and mineral damage evaluated by optical, electronic and confocal microscopies and hyperspectral imaging technique. The results showed that, regardless of the graffiti colour to be cleaned, quartz and K-feldspar grains were satisfactorily cleaned at the same fluence range. However, in case of plagioclase, it depends on the colour of graffiti to be removed. In case of biotite the analytical techniques allowed to confirm that it was already cleaned with the lowest fluence tested and it was the mineral with the highest sensitivity to laser radiation. Therefore, in order to obtain a satisfactory and safe laser cleaning it would be required the prior identification of the granitic forming minerals to adjust the laser fluence.

This paper is focused on the reliability of the colour spectrophotometry as a non-destructive in situ technique to evaluate the cleaning effectiveness. A biofilm composed by filamentous green algae and cyanobacteria developed on a granitic building located in NW Iberian Peninsula was removed using different cleaners commonly used by professionals in stone conservation (distilled water, ethanol, benzalkonium chloride, Hyvar X , ethanol, sodium hypochlorite and the commercial products LimpiaFachadas1 and Biocida ). Also, the durability of some water repellents applied after the cleanings was evaluate. The colour measurements expressed in the CIEL*a*b* colour space were performed before and after the cleanings and after the water repelling products application, at eight moments during two years (since June 2011 until June 2013) of exposition under a temperate humid climate. As general results, the colour spectrophotometry resulted in a reliable method to monitor the cleaning effectiveness, allowing to identify the most effective methods, but also the rate of the recolonization of the granitic surface during time. However, this technique was not recommended as re-growth indicator when water repellents were applied after the cleanings, due to the impact produced by the products on the colour of the stone.

Conservation strategies to reduce the degradation of stone caused by the action of water are focusing on increasing the hydrophobicity of the surface by imitating existing solutions in nature (lotus leafs and others). These are mainly based on the existence of hierarchical roughness with micro- and nanoscale structures. In the case of marble, research has focused on protective coatings that sometimes are dangerous for the health and the environment, and with undesirable effects such as color changes or reduction of water vapor permeability of the stone. Laser texturing, however, is an environmentally friendly technique, because no chemicals or toxic waste are added and, moreover, it can process nearly all types of materials. It has been used to change the surface texture of metals and other materials on a micro or even nanometric scale, to meet a specific functional requirement, such as hydrophobicity. The objective of this work was to analyze the feasibility of this technique to provide hydrophobic properties to a marble surface without appreciable changes in its appearance. Therefore, an analysis of the irradiation parameters with ultra-short-pulse laser was performed. Preliminary results demonstrate the ability of this technique to provide hydrophobic character the marble (contact angles well above 90 ∘ ). Besides, the analysis of the treated surfaces in terms of roughness, color and gloss indicates that changes in the appearance of the surface are minimal when properly selecting the process parameters.

During the 20th century, the need for raw material promoted a commercial transportation trade of iron ores from the deposits in north-western Spain, where Vigo city was considered one of the most important ports. The global energy crisis in the 1970s, as well as the strong competition from other exporting countries, dented the prolific activity of companies dedicated to the extraction and trading of iron ore. The main goal of this article is the evaluation of one particular element of the mining and industrial heritage — two old mineral loading docks in Ria de Vigo in the Rande Strait, linking the municipalities of Redondela and Moana. Their development as a tourist resource would add to the cultural and economic activities already developed in the area.

Stone coatings, biological colonization, efflorescence and detachments are frequent on granitic surfaces of our cultural heritage infrastructure. In order to find the different origins for each deterioration form, this paper studies and compares several coatings, efflorescence and flakes found on granitic surfaces of bridges from different ages built in the same area (Ourense in NW Iberian Peninsula at 90 km from the sea) under the same environmental and traffic conditions. The most recent bridge was the New Bridge built in the beginning of 20th century and the oldest one was the Roman Bridge with the 1st century AD foundations but its current structure was built in 17th century. The New Bridge has exhibited a greater variety of deterioration forms such as black crusts, carbonate crusts, efflorescence and biological colonization. On the Roman Bridge, black crusts, efflorescence to a greater extent, and flakes associated with salt crystallization processes have been identified. Scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray diffraction and Fourier transform infrared (FTIR) spectroscopy studies were carried out in order to establish their composition, and optical and electronic microscopies and X-ray microtomography were used to study their morphologies. As a result, anthropogenic factors (industrial activities, traffic pollution and fertilizers) are considered to be the main contributors to crusts, efflorescence and flake formation on both studied substrates (granite ashlars and mortars). To a lesser extent, natural factors (marine influence and bird droppings) should be taken into account.

A study of the cleaning effectiveness of sulphated black crust developed on granite is presented. The sulphated black crust, previously characterized, was subjected to a cleaning by 1) a mechanical procedure –Hydrogommage– based on micro-sandblasting, 2) chemical procedures based on the application of poultices made on different mixes of thickening agents and cleaners and 3) laser cleaning using a 355 nm Nd:YVO4 nanosecond laser. Chemical, mineralogical and physical characterization of the cleaned surfaces were performed; the global effectiveness as well as the harmfulness were evaluated according to the level of black crust removal and the substrate damages. As result, none of the methods has been completely effective in removing the sulphated black crust and, also, all the methods produced undesirable effects on the stone. The crust nature, its degree of interaction with the stone and other factors related to the principle of the cleaning procedures were found as the main variables influencing the effectiveness of the cleaning procedures.

This paper reports the results from the comparative evaluation of the global cleaning effectiveness of four graffiti colours (red, blue, black and silver) applied on two granites with different textures and compositions. A conventional mechanical method and several chemical products were evaluated. Additionally, it was evaluated the cleaning based on laser ablation by means of a nanosecond pulsed Nd:YVO 4 at a wavelength of 355 nm. Optical and electronic microscopy, Fourier transformed infrared spectroscopy and spectrophotometry were applied in order to assess the cleaning effectiveness and also the harmful effects on the stones. Taking into account the graffiti extraction degree, it was found that blue, red and black colours were successfully extracted by all the evaluated methods. However, the extraction of silver colour, whose chemical composition differs from that of the other three colours, was more difficult and it was only achieved by the mechanical procedure and by several chemical products; Nd:YVO 4 laser at 355 nm was an ineffective procedure in removing this paint. All the cleaning methods produced damage on the granites: a roughness increase after the mechanical cleaning, chemical contamination related to some chemical procedures and melting of biotite crystals after laser cleaning. Moreover, the ability of different paints to penetrate into the rock affected the global cleaning effectiveness evaluation.

As the UN Agenda 2030 recognizes heritage protection in several goals, this research was focused on the improvement of the graffiti removal from stones. The cleaning of two graffiti paints with different composition (an alkyd- and an acrylic&ndash, based paints) from two stones (gneiss and travertine) was performed considering a synergistic approach based on the combination of a low-toxic solvent ternary mixture, followed by an Nd:YAG laser. The different concentrations of the low-toxic solvents were based on the triangular Teas graph, keeping similar Hansen solubility of the products commonly used in conservation of cultural heritage: methyl ethyl ketone (MEK) and n-butyl acetate. The n-butyl acetate was replaced by mixture A (51% ethyl alcohol/11% acetone/38% isooctane) and MEK by mixture B (7%/13%/80%). Regardless of the graffiti composition, the gneiss was satisfactorily cleaned with the mixture A, while for the travertine, the best results were achieved by the mixture B. Then, surfaces treated with the mixtures were irradiated with a QS Nd:YAG laser working at 532 nm. The cleaning evaluation was performed by stereomicroscopy, color spectrophotometry, roughness measurements, reflectance measurements, and scanning electron microscopy. As result, regardless on the stone and the graffiti paints, it was confirmed the enhancement of cleaning of the mixtures followed by the Nd:YAG laser. However, it is crucial to identify previously the concentrations of the chemical products that allow the best performance considering the graffiti-stone interaction, on the one hand, and the optimal laser&rsquo, s parameters, on the other hand.

Nowadays, graffiti paints are one of the most common human interventions on monuments and historic facades with damaging results. It is an aesthetic problem but also a serious threat to the conservation of built heritage. The aim of this article is to evaluate the suitability of a hyperspectral imaging technique as a non-destructive tool to determine the most adequate method of removing graffiti paints applied on granite rocks. Different cleaning procedures were analyzed; i.e., chemical, mechanical, and laser ablation. The cleaning effectiveness was evaluated based on the degree of paint extraction and the final appearance of the stone surface. The results obtained by hyperspectral technique were compared with those obtained by optical and electronic microscopies and color spectrophotometry. These results indicate the ability of hyperspectral imaging technique to assess the paint removal and thus to evaluate the suitability of the different graffiti cleaning procedures. © 2016 Wiley Periodicals, Inc. Col Res Appl, 2016

Soluble salts are considered a main cause of damage of porous building materials such as rocks, bricks or granites, which were commonly used in the building constructions of the architectural and archaeological heritage. Soluble salts are also responsible for various forms of deterioration such as sand disaggregation and superficial detachments. These problems can be solved by conservation technologies, which are aimed to decrease the salt concentration in rocks (desalination). The present study aimed to investigate the efficiency of electrokinetic techniques for desalination of two different kinds of rocks: granite and sandstone. These rocks were contaminated with NaCl solution, and samples with a thickness of 6 cm were used in the tests. This study compared the percentage of salt removal at different depths (efficacy) and the time needed to get the same percentage removal (effectiveness) achieved in both stones. From the results obtained, it was possible to find those inherent factors to each stone which could have an influence on the efficacy of the treatment. With this technique it was possible to reduce the salt concentration in the granite almost to 100%. However, in the sandstone samples the decreases were not equally high, mainly at the intermediate levels where slight enrichments were observed. The results indicate that although the used technique is efficient for salt removal regardless of the porosimetric distribution of the rock, the better interconnection between the pores in the granite samples (favored a faster desalination process).

In this paper, we present a study of the application of the hyperspectral imaging technique in order to non-destructively evaluate the laser cleaning of the biogenic patina and the sulphated black crust developed on a fine-grained granite used in the construction of Cultural Heritage in NW Spain. The grained polymineral texture of the granite hinders the adjustment of laser irradiation parameters during the cleaning, and therefore the in situ process control. The cleaning was performed with a nanosecond pulsed Nd:YVO4 laser at 355 nm. A hyperspectral camera was used to in situ assess the effectiveness of cleaning by recording images of the rock surfaces before and during the laser treatment. Different analytical techniques were used to test the ability of the hyperspectral imaging technique to evaluate the cleaning process of the granite samples: optical microscopy, scanning electron microscopy with energy dispersive X-ray spectrometry (SEM - EDX), Fourier transform infrared spectroscopy (FTIR) and spectrophotometer colour measurements. The results indicated that hyperspectral imaging technique is a reliable and more affordable technique to in situ evaluate the process of laser cleaning of the biogenic patina and the sulphated black crust in fine-grained granites.

In order to understand the behavior of the natural hydraulic lime, pure lime and lime cement-based mortars as a repair mortar it is necessary to investigate their mechanical-properties. In this paper, the specimens were made with limestone aggregate as the restorers prepared the restoration works. The mechanical-strength as well as the evolution of Young’s modulus and the drying shrinkage were monitored. The study was performed under curing conditions which lead to the development of a suitable mortar strength within the first 28 days without having to wait for longer curing periods. The study revealed that NHL5 (1:1.75) mortar exhibits, for 28 days in a 70 ± 5% RH chamber, better results from the point of view of strength and shrinkage. A NHL5 (1:1.75) mortar could be a good candidate to be used like a repair mortar due to its good response to the movements of the stones in the buildings and its higher strengths. However the shrinkage in a lime cement-based mortar as well as a pure lime-based mortar is high enough as to cause a decrease in their strength. This information is very useful for the design of repair mortars.

En este trabajo se realiza la determinación del diámetro de zeo lita óptimo que es empleado como soporte microbiano en un react or aerobio de lecho fluidizado. El d iseño de dicho reactor es reco mendado por Navarro y Palladino [1]. Para el presente estudio, la zeolita es triturada y clasificada granulométricamente. Posteriormente, so n escogidos, arbitrariamente, los diámetros 0.5, 1 y 2 mm para realizar el estudio de adhesión microbiana. Tras el estudio de adherencia d e bacterias nitrificantes, a pesar de que los valores obtenidos para cada diámetro no presentan diferencias significativas entre sí, se e scoge el agregado de 1 mm por conseguir valores de adherencia m ayores. Una vez escogido el diámetro de zeolita se realiza la construcc ión del reactor aerobio de lecho fluidizado propuesto por Navar ro y Palladino [1], con una alimentación de 1.35 mL.m -1 y una capacidad de 8 L. La cantidad de zeolita optimizada para una correcta fluidización es de 500 g, lo que es un 8% del volumen total de la columna. Se observa una buena eficiencia de reducción de la materia orgánica durante el funcionamiento, siendo esta de 50%.

Mechanical methods to extract undesired graffiti paints on ornamental stones are efficient cleaning methods from an economical point of view. However, effort on the optimization of mechanical cleaning procedures to avoid any damage to the substrate is required for large areas. In this study, two ornamental stones with different composition and texture, and which are commonly used in Spain and Portugal were selected: Granite Vilach&aacute, n and Limestone Lioz. Moreover, the most common surface finishes were selected-disc-cutting and bush-hammering to simulate the stones found in buildings. Two graffiti spray paints were selected: Blue Ultramarine and Silver Chrome. As cleaning methods, three soft-abrasive blasting procedures: Hydrogommage (mixture of air&ndash, water&ndash, micro grained silicon abrasive), IBIX (mixture of air&ndash, micro grained silicon abrasive), and dry-ice procedure (carbon dioxide ice pellets), were tested at pressure below 0.4 MPa. The methodology for evaluating the effectiveness and harmfulness of each cleaning method was based on stereomicroscopy, scanning electron microscopy, color spectrophotometry, and confocal microscopy. As result, IBIX achieved the highest level of graffiti paint extraction although this method increased the surface roughness. Conversely, cleaning based on dry-ice projection did not achieve a satisfactory extraction of the graffiti, mainly of the blue paint. Dry-ice blasting can induce acid environments and IBIX causes dust emission during the projection. Hydrogommage was the most efficient cleaning method amongst the tested procedures, because it induced the lowest roughness change and although the graffiti extraction was not complete, it achieved the highest removal level. Therefore, the most satisfactory cleaning method was that achieving a satisfactory extraction level, minimal modifications of the surface roughness, an economic suitability, an environmental integration, and lower human health risks.

the need to create a method that eliminates the subjectivity at the moment of valuing a landscape, is one of environmental topics which is more important in the last years. Environmentalists and engineers have been invested a lot of time on this matter .the purpose that is chased is to extend the traditional concept of creating sure and economic slopes to doing them more integrated in the environment. this technology can help to mitigate Landscape impact, doing the least harmful works at sight and realizing projects of exploitation with integrated Closings to the environment. It makes a comparative between a direct method of landscape valuation and an indirect method based on the evaluations of a series of parameters (physiography, artificial elements, water, vegetation, etc.).