Mortar Characterization of Historical Masonry Damaged by Riverbank Failure: The Case of Lungarno Torrigiani (Florence)

The research of structural masonry associated with geo-hydrological hazards in Cultural Heritage is a multidisciplinary issue, requiring consideration of several aspects including the characterization of used materials. On 25 May 2016, loss of water from the subterranean pipes and of the aqueduct caused an Arno riverbank failure damaging a 100 m long portion of the historical embankment wall of Lungarno Torrigiani in Florence. The historical masonry was built from 1854–1855 by Giuseppe Poggi and represents a historical example of an engineering approach to riverbank construction, composed of a scarp massive wall on foundation piles, with a rubble masonry internal core. The failure event caused only a cusp-shaped deformation to the wall without any shattering or toppling. A complete characterization of the mortars was performed to identify the technologies, raw materials and state of conservation in order to understand why the wall has not collapsed. Indeed, the mortars utilized influenced the structural behavior of masonry, and their characterization was fundamental to improve the knowledge of mechanical properties of civil architectural heritage walls. Therefore, the aim of this research was to analyze the mortars from mineralogical–petrographic, physical and mechanical points of view, to evaluate the contribution of the materials to damage events. Moreover, the results of this study helped to identify compatible project solutions for the installation of hydraulically and statically functional structures to contain the riverbank

Monitoring and evaluation of sandstone decay adopting non-destructive techniques: On-site application on building stones

This paper focuses on the characterization approach to evaluate the decay state of Pietra Serena of historic buildings in Florence (Italy). Pietra Serena is a Florentine sandstone largely used in the city especially during the Renaissance; it is a symbol of cultural heritage of Florence and constitutes a large part of the city center, which was named a World Heritage Site by UNESCO in 1982. Unfortunately, many environmental factors negatively affect the stone, increasing damage and the danger of falling material. Any detachment of stone fragments, in addition to constitute a loss in cultural heritage, can be dangerous for citizens and the many tourists that visit the city. The use of non-destructive techniques (NDTs) as ultrasonic and Schmidt hammer tests can quantitatively define some mechanical properties and help to monitor the decay degree of building stone. In this study, the NDTs were combined with mineralogical, petrographical, chemical and physical analyses to investigate the stone materials, in order to correlate their features with the characteristics of the different artefacts in Pietra Serena. Correlations between the NDTs results and the compositional characteristics of the on-site stone were carried out; such discussion allows to identify zones of weakness and dangerous unstable elements

A Multidisciplinary Methodology for Technological Knowledge, Characterization and Diagnostics: Sandstone Facades in Florentine Architectural Heritage

The Historic Center of Florence, a UNESCO World Heritage Site, includes many examples of architecture characterized by rough-hewn rusticated block facades—a very common masonry technique in the Florentine Renaissance—made in Pietraforte sandstone. The latter features numerous criticalities related to its intrinsic characteristics and to decay phenomena that are due to weathering and pollution. A multidisciplinary methodology has been developed starting from historic analysis and architectural survey to a complete optometric, mechanical, physical, mineralogical, and petrographic characterization of rough-hewn rusticated blocks, applied to the case study of the Palazzo Medici Riccardi facades. The studies performed in this work cover several research fields, from architecture to geology, going through material diagnostics, and aim at improving knowledge and designing new restoration solutions for Pietraforte building-material criticalities. The research proposes an operative protocol aimed at supporting restoration projects and monitoring plans, with the aim to protect historical, architectural, and artistic cultural heritage and to safeguard the people who visit the city of Florence every year

A Multidisciplinary Methodology for Technological Knowledge, Characterization and Diagnostics: Sandstone Facades in Florentine Architectural Heritage

The Historic Center of Florence, a UNESCO World Heritage Site, includes many examples of architecture characterized by rough-hewn rusticated block facades—a very common masonry technique in the Florentine Renaissance—made in Pietraforte sandstone. The latter features numerous criticalities related to its intrinsic characteristics and to decay phenomena that are due to weathering and pollution. A multidisciplinary methodology has been developed starting from historic analysis and architectural survey to a complete optometric, mechanical, physical, mineralogical, and petrographic characterization of rough-hewn rusticated blocks, applied to the case study of the Palazzo Medici Riccardi facades. The studies performed in this work cover several research fields, from architecture to geology, going through material diagnostics, and aim at improving knowledge and designing new restoration solutions for Pietraforte building-material criticalities. The research proposes an operative protocol aimed at supporting restoration projects and monitoring plans, with the aim to protect historical, architectural, and artistic cultural heritage and to safeguard the people who visit the city of Florence every year

Industrial Ceramics: From Waste to New Resources for Eco-Sustainable Building Materials

Today, the need to dispose of a huge amount of ceramic industrial waste represents an important problem for production plants. Contextually, it is increasingly difficult to retrieve new mineral resources for the realization of building materials. Reusing ceramic industrial waste as precursors for building blocks/binders, exploiting their aluminosilicate composition for an alkaline activation process, could solve the problem. This chemical process facilitates the consolidation of new binders/blocks without thermal treatments and with less CO2 emissions if compared with traditional cements/ceramics. The alkali-activated materials (AAMs) are today thought as the materials of the future, eco-sustainable and technically advanced. In this study, six different kind of industrial ceramic waste are compared in their chemical and mineralogical composition, together with their thermal behaviour, reactivity in an alkaline environment and surface area characteristics, with the aim of converting them from waste into new resources. Preliminary tests of AAM synthesis by using 80%–100% of ceramic waste as a precursor show promising results. Workability, porosity and mechanical strengths in particular are measured, showing as, notwithstanding the presence of carbonate components, consolidated materials are obtained, with similar results. The main factors which affect the characteristics of the synthetized AAMs are the precursors’ granulometry, curing temperature and the proportions of the activating solutions

Virtual inspection based on 3D survey supporting risks detachment analysis in Pietraforte stone built heritage

The paper presents the first results of a multidisciplinary research project launched to support the conservation and restoration of the stone façades of the Pitti Palace in Florence with innovative techniques from the fields of geomatics and diagnostic analysis. Monitoring campaigns are periodically conducted on the façades of the palace to identify stone elements in critical conditions; such surveys primarily require close and careful observation of the façade, for which a crane basket is required. The paper proposes first attempt to compare results obtained through a traditional workflow with those coming from a deeper use of the high-resolution 3D model to conduct a virtual inspection and to map elements of vulnerability on a GIS. On a test area, the analysis of the factors considered relevant to the risk of detachment was carried out on the digital model and compared with what the experts observed on-site by carrying out Non-Destructive diagnostic tests. Traditionally conducted monitoring and diagnostic surveys are assumed to validate the proposed method, which, following a simple data analysis, remotely identifies all blocks detected as vulnerable by the in-situ inspection, potentially drastically reducing fieldwork. It is therefore proposed as a preliminary screening useful to better address further analysis

Increased Perioperative N-Terminal Pro-B-Type Natriuretic Peptide Levels Predict Atrial Fibrillation After Thoracic Surgery for Lung Cancer

Background— Postoperative atrial fibrillation (AF) is a complication of thoracic surgery for lung cancer, with a reported incidence that can run as high as 42%. Recently, it has been observed retrospectively that B-type natriuretic peptide predicts AF after cardiac surgery. We performed a prospective study to evaluate the role of N-terminal pro–B-type natriuretic peptide (NT-proBNP) as a marker for risk stratification of postoperative AF in patients undergoing thoracic surgery for lung cancer. Methods and Results— We measured NT-proBNP levels in 400 patients (mean age, 62±10 years; 271 men) 24 hours before and 1 hour after surgery. The primary end point of the study was the incidence of postoperative AF. Overall, postoperative AF occurred in 72 patients (18%). Eighty-eight patients (22%) showed an elevated perioperative NT-proBNP value. When patients with either preoperatively or postoperatively elevated NT-proBNP were pooled, a greater incidence of AF was observed compared with patients with normal values (64% versus 5%; P <0.001). At multivariable analysis, adjusted for age, gender, major comorbidities, echocardiography parameters, pneumonectomy, and medications, both preoperative and postoperative NT-proBNP values were independent predictors of AF (relative risk, 27.9; 95% CI, 13.2 to 58.9; P <0.001 for preoperative NT-proBNP elevation; relative risk, 20.1; 95% CI, 5.8 to 69.4; P <0.001 for postoperative NT-proBNP elevation). Conclusions— Elevation of perioperative NT-proBNP is a strong independent predictor of postoperative AF in patients undergoing thoracic surgery for lung cancer. This finding should facilitate studies of therapies to reduce AF in selected high-risk patients

Application of a physically based model to forecast shallow landslides at a regional scale

<p>In this work, we apply a physically based model, namely the HIRESSS (HIgh REsolution Slope Stability Simulator) model, to forecast the occurrence of shallow landslides at the regional scale. HIRESSS is a physically based distributed slope stability simulator for analyzing shallow landslide triggering conditions during a rainfall event. The modeling software is made up of two parts: hydrological and geotechnical. The hydrological model is based on an analytical solution from an approximated form of the Richards equation, while the geotechnical stability model is based on an infinite slope model that takes the unsaturated soil condition into account. The test area is a portion of the Aosta Valley region, located in the northwest of the Alpine mountain chain. The geomorphology of the region is characterized by steep slopes with elevations ranging from 400 m a.s.l. on the Dora Baltea River's floodplain to 4810 m a.s.l. at Mont Blanc. In the study area, the mean annual precipitation is about 800–900 mm. These features make the territory very prone to landslides, mainly shallow rapid landslides and rockfalls. In order to apply the model and to increase its reliability, an in-depth study of the geotechnical and hydrological properties of hillslopes controlling shallow landslide formation was conducted. In particular, two campaigns of on site measurements and laboratory experiments were performed using 12 survey points. The data collected contributed to the generation of an input map of parameters for the HIRESSS model. In order to consider the effect of vegetation on slope stability, the soil reinforcement due to the presence of roots was also taken into account; this was done based on vegetation maps and literature values of root cohesion. The model was applied using back analysis for two past events that affected the Aosta Valley region between 2008 and 2009, triggering several fast shallow landslides. The validation of the results, carried out using a database of past landslides, provided good results and a good prediction accuracy for the HIRESSS model from both a temporal and spatial point of view.</p