Ylenia Praticò

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Praticò

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Ylenia

ORCID

0000-0002-8418-2336

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Publications 1 - 8 of 8

Stone consolidation: a critical discussion of theoretical insights and field practice
Praticò, Ylenia; Caruso, Francesco; Delgado Rodrigues, José; et al. (2020)
RILEM Technical Letters
Stone consolidants have been extensively used for the preservation of historical structures since the 19th century. However, their true effectiveness in practice is often a source of debate, largely because of known cases where badly chosen treatments were unsuccessful, or even caused an accelerated degradation of the substrate. Researchers have therefore strived to better understand, and possibly predict, the behavior of consolidants on-site, in order to assist practitioners in their decision making. Despite the large number of publications available on the subject, however, the contribution of scientific research for practical applications remains scarce. Reasons for this include the limited accessibility of scientific publications and the lack of documentation or preparatory studies from the field. This unfortunately compromises the knowledge exchange between researchers and practitioners, which we consider to be a main challenge that this field must overcome. The target of this letter is to reconnect the critical problems identified on-site through practical experience with the conceptual research outcomes that could help solve them. For this, we present an informed evaluation of the most needed research, along with a synthetic overview of the insights that scientific research can offer in terms of consolidant selection, application and monitoring.
Post-fire restoration of historic buildings and implications for Notre-Dame de Paris
Praticò, Ylenia; Ochsendorf, John; Holzer, Stefan; et al. (2020)
Nature Materials
The restoration of fire-damaged historical monuments entails a wide range of scientific questions. Taking as a starting point the case of Notre-Dame de Paris, this Comment defines the materials science challenges of post-fire restoration, and also briefly outlines the issues of structural integrity, fire safety and preservation ethics.
Mesures des mouvements d’eau à la cathédrale de Lausanne et réflexions sur leur rôle dans la dégradation de la pierre
Praticò, Ylenia; Girardet, Fred; Scherer, George W.; et al. (2021)
Piscis Aqua: Exposition de la molasse à l'eau, altérations et propositions: Actes du colloque du 29 janvier 2021
Les études menées au cours des dernières décennies ont de plus en plus mis en évidence l'importance de la relation entre l'exposition à l'eau et le développement de dommages dans les monuments suisses, en particulier dans les grès suisses contenant des argiles gonflantes. Dans cette optique, une récente campagne de mesures effectuée à la cathédrale de Lausanne a été centrée sur la mesure directe de l'exposition à la pluie, ainsi que sur la répartition de l'eau dans la profondeur des pierres. Les évaluations photographiques ont permis de corréler le type d'exposition à la pluie avec les formes d'altération observées localement. Les mesures directes de la pluie battante ont permis de quantifier les quantités d'eau reçues sur les façades avec des orientations différentes pour chaque événement pluvieux. Ceci a permis de calculer la profondeur de pénétration de l'eau pendant les épisodes de pluie et de prévoir l'occurrence du ruissellement. Les résultats ont montré que la gravité des dégâts n'est pas proportionnelle à la somme d'eau reçue pendant une année. En outre, le ruissellement ne se produit pas très souvent, ce que confirme l’observation d’une accumulation de gypse à des profondeurs élevées. Des mesures en continu de l'impédance, ainsi que de la température et de l'humidité, ont permis de mesurer la répartition de l'eau jusqu'à une profondeur de 27 cm sous la façade. Les résultats montrent pour la première fois que les pierres de la cathédrale de Lausanne contiennent de grandes quantités d'eau liquide dans leur profondeur pendant toute l’année, même lorsque la façade semble sèche. En outre, une accumulation particulièrement importante d'eau d'environ 6 cm a été détectée pendant les mois d'hiver, ce qui suggère que les dommages causés par le gel pourraient avoir joué un rôle important dans la formation de l'écaillage des contours au cours des siècles suivant la construction de la cathédrale. Ces résultats constituent une première étape dans la clarification du mécanisme de développement des dommages à la cathédrale de Lausanne en fonction de l'exposition locale à l'eau, et jettent les bases pour des études ultérieures, qui devraient idéalement impliquer le développement d'un modèle de calcul du transport de l'eau dans la pierre.
New insights on the causes of contour scaling in Swiss sandstone
Praticò, Ylenia; Girardet, Fred; Flatt, Robert J. (2020)
Monument Future: Decay and Conservation of Stone. Proceedings of the 14th international Congress on the Deterioration and Conservation of Stone
Practical applications of science for the conservation of built heritage
Praticò, Ylenia (2020)
The common goal of researchers and practitioners in conservation of monuments is to stretch as much as possible the lifespan of built heritage. However, despite this common target, work carried out in the laboratory and on the field are all too often disconnected. In the context of stone consolidation, for example, practitioners are often skeptical about treatment recommendations emerging from laboratory studies, due to the often-questionable representability of the tests employed. To improve this situation, we describe the development of a research approach that would allow researchers to more pragmatically assist conservators in their decision-making, while also achieving a broader scientific significance. In particular, we discuss the application of this strategy for conservation treatments applied to swiss monuments built out of molasse sandstones. These stones contain swelling clays, which makes them particularly susceptible to weathering. The difficulty in preserving such substrates is exacerbated by the lack of effective consolidation treatments, since common ethyl silicate-based products (TEOS) tend to lose their effectiveness shortly after application. A possible solution lies in using swelling inhibitors that have been shown in laboratory to potentially extend the durability of consolidation treatments. However, it is still not clear in which specific conditions these treatments would be worth applying. We used a Design of Experiment (DOE) to analyze the simultaneous effects of varying environmental conditions and treatments procedures on the effectiveness of TEOS-based consolidation and swelling inhibition treatments for swiss molasses. We showed that the application of ethyl silicates at high relative humidity and low temperature greatly decreases their curing time, without compromising their effectiveness. We also demonstrated that swelling inhibitors effectively improve the durability of ethyl silicate consolidation treatments. In terms of accelerated testing, we developed an automated machine for simulating “critical events” (i.e., a specific combination of damaging conditions leading to the most damage) in the laboratory. We attempted to identify critical cycles at the cathedral of Lausanne, by characterizing wetting and drying conditions at the façade depending on orientation, and monitoring the materials response to the weathering conditions through measurements of the water movement throughout the depth of the stone. At orientations typically presenting severe damage, a critical distribution of water can be observed at a depth of 6 cm during the winter months, suggesting that freezing might play a crucial role in the initiation of contour scaling. This water profile is not created by individual critical events, but results from an overall cumulation of events. Once established, it remains probable that degradation is caused by specific events, but these still remain to be clearly defined and reproduced in laboratory. Ongoing laboratory experiments under simulated on-site conditions are presented, which aim at clarifying the mechanism of accumulation of water at those depths.
Statistical Analysis at the Service of Conservation Practice: DOE for the Optimisation of Stone Consolidation Procedures
Praticò, Ylenia; Caruso, Francesco; Wangler, Timothy; et al. (2016)
Science and Art: A Future for Stone. Proceedings of the 13th International Congress on the Deterioration and Conservation of Stone
Ethyl silicates are extensively used in the field of conservation to treat various types of stones. It is common belief that the different conditions of temperature, humidity and techniques of application influence the resulting consolidation. In this study, a statistical Design of Experiments (DOE), that allows the exploration of the simultaneous effect of different factors in a limited number of experiments, is used to study this. It is applied to analyse the possible crossed effect of temperature, relative humidity, application procedure, concentration and pre-treatment with a swelling inhibitor on the consolidation of a swelling clay-bearing sandstone. The purpose is to obtain an optimization of the consolidation treatment under conditions that are both reliable in the laboratory and on site. The results obtained with our approach show that the consolidation is not affected by temperature, humidity or the application method. On the other hand, the curing time is strongly influenced by the above-mentioned factors. In particular, it is shown that higher initial moisture content is beneficial to the consolidation treatment as it significantly shortens the curing time.
Planar Abrasion Meter
Sikorowski, Gabriel; Piqué, Francesca; Praticò, Ylenia (2020)
Monument Future: Decay and Conservation of Stone. Proceedings of the 14th international Congress on the Deterioration and Conservation of Stone
Water Transport and the Degradation of Sandstone Monuments: Following the Water Trail at Lausanne Cathedral and Its Swiss Molasse Sandstone
Weichbrodt, Anjo; Praticò, Ylenia; Girardet, Fred; et al. (2025)
International Journal of Architectural Heritage
Exposure to water damages building stones, particularly those containing swelling clays. This motivated direct measurement of exposure to rain and related air movements, as well as the distribution of water inside the stones, at the Lausanne Cathedral. Wind-driven rain (WDR) measurements quantified the amount of water reaching facades with different orientations for each rain event. Anemometers provided the direction and speed of localized airflows driving the precipitation to the building envelope. With this information, the rate of water reaching the surface of the stone could be compared with the sorption rate of the stone to predict the occurrence of runoff. Results imply that the severity of the damage is not proportional to the amount of water received during a year and that runoff does not occur very often, pointing to the importance of the wetting-drying frequency and the drying kinetics. Continuous measurements of impedance, as well as temperature and relative humidity, reveal the water distribution within fa & ccedil;ades. Results show large quantities of liquid water in their interior throughout the year, even when the fa & ccedil;ade appears dry, suggesting that frost damage could have played a role in the formation of contour scaling. Additionally, pronounced wetting-drying cycles, observed within the first 4 cm coincide with disintegration processes manifesting parallel to the surface.

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Ylenia Praticò

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