An innovative multidisciplinary methodology to evaluate the conservation state of cultural sites as a whole: “Casa di Diana" (Ostia Antica, Italy)

Archaeological sites, perceived as open museums, are particularly complicated to study because of the extensive number of environmental stressors affecting their conservation state. Diagnostic methodologies can easily omit some of them, causing irreparable and inestimable damages to these sites. In this sense, multidisciplinary studies seem to constitute the most suitable approach to understand the decaying processes that occur. Up until now, these types of studies have been applied within local programmes, leading to loss of strategic output, risk of duplication and reduction in the international competitiveness of the research. Therefore, in this Joint Doctoral Thesis, a new protocol for the preservation and accessibility of the archaeological sites, based on the synergic combination of physical, geological and analytical chemistry methodologies, is presented, in order to understand the sites as a whole. The project was born in 2012 within a multidisciplinary study on Ostia Antica Mithraea, as the result of my master degree. Successively, thanks to an international cooperation (Italy-Spain) and institutional effort (National and International Research centers and Departments) it was possible to combine different disciplines developing a new analytical approach. The final aim of this approach was assess the conservation state of the building under study, pointing out the areas most at risk, resolving important issues emerged during the investigation, and identifying the origin of the decay, suggesting also possible repair tools. The diagnostic protocol consists in a dynamic model, developed as a pyramid that includes three steps or levels that can be summarised into anamnesis (the state of art, the macroscopic observation on both environment and materials), analysis (the development of a protocol that includes the investigation actions that lead to the identification of damage’s sources) and a conservation step (the real state of conservation of the site under study). This last action also considers some suggestions for a future and global conservation and lays the “ad-hoc designing” to create a whole conservation plan. The final goal is the conservation, safeguard and “usability” of open museums or cultural sites in general, thanks to the protocol flexibility, organised in steps procedures. The base of the pyramid is built on an initial hypothesis based on the “content and container” axiom, the relationship between the environment and the materials. In order to validate the proposed diagnostic protocol, the model has been implemented in a complex building, the “Casa di Diana” Mithraeum, a Roman masonry dated 130 CE, found in Ostia Antica (Italy), the port of the old city of Rome, obtaining a well-developed pyramid. The rising damp represents the key between all the actions successively developed, both geophysical and chemical surveys, and is the result of a synergic interaction. Thanks to the well-planned multi-analytical procedure, the results obtained point out towards the rising damp and acids gases as the main environmental stressors. It was possible to associate the rising damp to the presence of freshwater at shallow depth, which causes the preliminary hydration phase on bricks, and the attack of the wall-building materials by the atmospheric acid gases through dry deposition mechanism. Furthermore, the results obtained by non-destructive spectroscopic analyses have led to the hypothesis that the observed yellow bricks could date back to a different historic period, for instance Byzantine, which corresponds to the last period of utilization of this house, while the red bricks derive from the Roman period. In addition to the new protocol, each methodology is characterised by several novelty keys, obtaining in this sense, 12 research articles published/reviewed on important international journals. Some processes of this multidisciplinary study involve an important economic effort, but the present method allows making an objective decision, through a solid analytical protocol, which has an important value in the management of Cultural Heritage

Three-dimensional reconstruction of a masonry building through electrical and seismic tomography validated by biological analyses

In this paper, we present an integrated approach, for assessing the condition of an ancient Roman building, affected by rising damp and cracking phenomena. The combination of high-resolution geophysical methods, such as seismic and electrical tomography, with biological information, allowed a more detailed evaluation of the state of conservation of the masonry building. A preliminary three-dimensional electrical survey was conducted to detect the existing building foundations and to determine the variation of the resistivity in the ground. Then, electrical and seismic tomography investigations were carried out on an inner wall of opus caementicium, subjected to rising damp effects and cracks. This approach was adopted to obtain a high-resolution image of the wall, which allowed to identify the inner mortar and the outer brick component from resistivity and velocity contrasts. Furthermore, the geophysical results revealed evidence of wall fractures (indicated by low velocity and high resistivity values) and a significant volume where rising of damp was taking place (resulting in a low resistivity zone). Biological analyses validated the geophysical model: in fact, the biological proliferation occurred up to a height of 0.75 m, where the interface between high and low resistivity values was recovered. This approach can be employed to reconstruct a three-dimensional model of masonry structures in order to plan recovery actions

The orientation of the Mithraea in Ostia Antica

We conducted an investigation on the orientations and geometrical content of the Mithraea of Ostia Antica. A geometrical CAD study based on the most reliable plans from the Archives of the Sovrintendenza Speciale per il Colosseo, il MNR e l’Area Archeologica di Roma – Ostia Antica, aside with the identification of geometrical and numerical schemes and associated length units, allowed us to identify the axes of the Mithraea. Then the orientations of the axes were measured on field by means of a professional compass with ± 0.5° uncertainty. The distribution of these measured azimuths follows the topography of the city. On the contrary, the Decumanus, the main street of the town, presents an indubitable orientation toward the Winter Solstice Sunset. This was ascertained by measuring the coordinates of four significant points along the street with the help of a palmar Trimble GPS which averages 100 measures per point. The exceptional density of Mithraea in Ostia led us to suppose that a symbolic cosmic-solar value is to be searched in the orientation as a whole of the town itself, founded half a millennium before the first presence of Mithraism in Rome. The Decumanus could be considered the very holder of this symbolic value with its orientation toward the Winter Solstice Sunset, possibly making of Ostia a very special place for Mithraicism

CARACTERIZACIÓN TERMOHIGROMÉTRICA DE MATERIALES DE CONSTRUCCIÓN DEL LUGAR ARQUEÓLOGICO DE OSTIA ANTICA MEDIANTE TOMA DE DATOS DISCRETA Y CONTINUA

[EN] Nowadays, the procedures and instruments for measuring temperatures on the air and materials surface are normed and amply used, through direct and indirect techniques, with the aim to evaluate the conservation status of ancient buildings. In this work, two monitoring procedures are discussed in order to characterise materials, bricks and mortar aligned with “opus caementicium” technique, that make up the framework of “Casa di Diana” Mithraeum, a roman building (130 CE) sited in an Italian archaeological site (Ostia Antica, Rome). In this sense, for one year the wall-building materials and the surrounding air were monitored with two different procedures: a direct multi-points measurement with several handheld instrument which different physical systems conduced in predetermined periods and a long-term monitoring campaign with sensors specially developed placed along the walls. Preliminary data analyses show that the discrete monitoring with punctually procedure gives important information like the evaporating and condensing risk for both materials and areas particularly critical associated at lower level (0-70 cm). Continuous monitoring allows the individuating of punctual characteristics in time and space, planning recovery actions, although it requires more data treatment. Preliminary data treatments show the potentiality and advantages of both methodologies: general information and more data treatment with automatic method and specific information and more time spends in data adquisition with a manually proceeding.[ES] En la actualidad, con el objetivo de evaluar el estado de conservación de edificios antiguos, los procedimientos e instrumentos para la medición de temperaturas del aire de y de la superficie de los materiales están estandarizadas y son ampliamente utilizados a través de técnicas directas e indirectas. En este trabajo, se discuten dos procedimientos de control con el fin de caracterizar los materiales, ladrillo y mortero, colocados con la técnica de "opus caementicium", que constituyen el marco del Mitreo de la "Casa di Diana", un edificio romano (130 dC) situado en el yacimiento arqueológico italiano (Ostia Antica, Roma). En este sentido, durante un año los materiales de construcción de muros y el aire circundante fueron monitorizados con dos procedimientos diferentes: uno mediante medición manual directa de múltiples puntos con varios instrumentos, realizado en períodos predeterminados y una campaña de monitorización continua a largo plazo con sensores especialmente desarrollados para este fin emplazados en las paredes. Análisis preliminares muestran que el sistema discreto aporta información importante de riesgo, como la evaporación y la condensación, tanto para los materiales como para las zonas especialmente aquellas más críticas (zona baja, 0-70 cm). La monitorización continua permite la individuación de las características puntuales en tiempo y en espacio, aunque requiere de un tratamiento de datos más extenso. Los análisis preliminares muestran la potencialidad y las ventajas de ambos métodos: información general con el método automático y un tratamiento de datos más extenso e información específica con un mayor consumo de tiempo en la toma de datos con un procedimiento manual.García Diego, FJ.; Scatigno, C.; Merello, P.; Scatig (2016). DISCRETE AND CONTINUOUS MONITORING TO CHARACTERISED THE THERMO-HYGROMETRIC STATE OF WALL-BUILDING MATERIALS IN OSTIA ANTICA ARCHEOLOGICAL SITE. En 8th International congress on archaeology, computer graphics, cultural heritage and innovation. Editorial Universitat Politècnica de València. 496-499. https://doi.org/10.4995/arqueologica8.2016.4183OCS49649

Soluble Salts Quantitative Characterization and Thermodynamic Modeling on Roman Bricks to Assess the Origin of Their Formation

The environmental weathering and the formation of efflorescences on the brick walls are studied at the “Casa di Diana” Mithraeum at Ostia Antica archaeological site. Previous studies on subsoil, bedrock, hydrological systems and environmental conditions, and new ion chromatography analysis combined with ECOS-RUNSALT and Medusa-Hydra thermodynamic modelling software, had allowed us to identify the subsoil contamination related to soluble salts. The atmospheric acidic gases, CO2 and SO2, are determined as the main salt weathering species. A dry deposition after a subsequent hydration action from the shallow freshwater aquifer that reaches up to 1 m on the walls is identified as the mechanism of salt formation. An evaluation of potential sources such as the nearby Fiumicino airport, CO2-rich gases inputs from fumaroles and CO2 inputs was also debated. The risk level of contamination the surfaces of the materials should be considered mildly/very polluted with a medium/high risk of hygroscopic moisture due to the high concentration of sulphates.This work has been supported by the DEMORA (Grant No. PID2020-113391GB-I00) projects funded by the Spanish Agency for Research AEI (MICINN/FEDER-UE)

MODELIZACIÓN MEDIANTE CFD DE PARA EVALUAR LA VENTILACIÓN EN UN EDIFICIO ARQUEOLÓGICO, DATOS PRELIMINARES.

[EN] The present study addresses the influences of wind flow structure, as an important factor responsible of material damage (erosion contributing) on “Casa di Diana” Mithraeum, a roman building (130 A.D.) sited on Ostia Antica (archaeological site, Rome – Italy), through the Computational Fluid Dynamics (CFD) simulations and direct measurements for its verification and validation (V&V). In this preliminary work, we present results relating to 3D reconstruction (geometry of the entire building) and the mesh importing on Fluent software. In general, the data check confirms, with ±10%, a good agreement (model) between the numerical solutions and direct measurements data by portable sensor. For this, the model proposed could be applied on similar cases, buildings characterised by different “boundary conditions”, to predict without direct measurements, the air movement in these ventilated spaces.[ES] El presente estudio aborda la influencia de la acción del viento en la estructura puesto que dicha acción es un factor relevante y responsable del daño material (contribuye en la erosión) del mítreo de la “Casa de Diana”, un edificio romano (130 A.C.) situado en Ostia Antica (sitio arqueológico, Roma, Italia), mediante las simulaciones de la dinámica de fluidos computacional y las mediciones de campo para su verificación y validación (V&V). En este trabajo preliminar, se presentan los resultados de un reconstrucción 3D (geometría del edificio entero) y del mallado importado al software Fluent. En general, la inspección de los datos confirma, con ±10%, un buen ajuste (modelo) de las soluciones numéricas y de las mediciones de campo adquiridas mediante un sensor portátil. Para ello, el modelo propuesto puede ser aplicado en casos similares, edificios caracterizados por diferentes condiciones de contorno, para predecir sin las mediciones de campo el movimiento del aire en estos espacios ventilados.García Diego, FJ.; Scatigno, C.; Merello, P.; Bustamante, E. (2016). PRELIMINARY DATA OF CFD MODELING TO ASSESS THE VENTILATION IN AN ARCHAEOLOGICAL BUILDING. En 8th International congress on archaeology, computer graphics, cultural heritage and innovation. Editorial Universitat Politècnica de València. 504-507. https://doi.org/10.4995/arqueologica8.2016.4191OCS50450

High Frequency Data Acquisition System for Modelling the Impact of Visitors on the Thermo-Hygrometric Conditions of Archaeological Sites: A Casa di Diana (Ostia Antica, Italy) Case Study

[EN] The characterization of the microclimatic conditions is fundamental for the preventive conservation of archaeological sites. In this context, the identification of the factors that influence the thermo-hygrometric equilibrium is key to determine the causes of cultural heritage deterioration. In this work, a characterization of the thermo-hygrometric conditions of Casa di Diana (Ostia Antica, Italy) is carried out analyzing the data of temperature and relative humidity recorded by a system of sensors with high monitoring frequency. Sensors are installed in parallel, calibrated and synchronized with a microcontroller. A data set of 793,620 data, arranged in a matrix with 66,135 rows and 12 columns, was used. Furthermore, the influence of human impact (visitors) is evaluated through a multiple linear regression model and a logistic regression model. The visitors do not affect the environmental humidity as it is very high and constant all the year. The results show a significant influence of the visitors in the upset of the thermal balance. When a tourist guide takes place, the probability that the hourly temperature variation reaches values higher than its monthly average is 10.64 times higher than it remains equal or less to its monthly average. The analysis of the regression residuals shows the influence of outdoor climatic variables in the thermal balance, such as solar radiation or ventilation.The authors would like to thank the staff of the archaeological area of Ostia Antica for the permission to work in this house. This work is partially supported by the projects HAR2013-47895-C2-1-P and HAR2013-47895-C2-2-P from MINECO.Merello Giménez, P.; García Diego, FJ.; Beltrán Medina, P.; Scatigno, C. (2018). High Frequency Data Acquisition System for Modelling the Impact of Visitors on the Thermo-Hygrometric Conditions of Archaeological Sites: A Casa di Diana (Ostia Antica, Italy) Case Study. Sensors. 18(2):1-15. https://doi.org/10.3390/s18020348S11518

Petrographic-Mineralogical Characterization of Archaeological Materials from “Casa di Diana” Mithraeum Sited in the Open Museum of Ostia Antica

Mithraea, religious Roman buildings, are very common in Italian archeological sites. There are sixteen in Ostia Antica (Rome, Italy)The poor state of conservation, due to the intrinsic environmental conditions, characterized them: they consist of open-air museums and caves simultaneously. These places of worship are characterized by the presence of heterogeneous materials, such as wall building materials (bricks and mortars) and others used for furnishings and fittings. This increases the risk of accelerated damage because the materials ‘rheology is different. Here, a full petrographic-mineralogical characterization with polarized light microscopy (PLM), X-ray diffraction (XRD), scanning electron microscope with energy dispersive X-ray (SEM-EDS) and isotopic analysis (δ13C, δ18O) is carried out on materials like travertine, marble, pumice, ceramic, and wall-building materials in “Casa di Diana” Mithraeum (Ostia Antica). Their characterization gives provenance information as well as conservation and restoration purposes. The prevalence of siliciclastic or carbonate components discriminates between red and yellow bricks, as well as different textures and minerals in the aggregate of the red ones. The mortars are typically pozzolanic, and the aggregate is mostly made up of black and red pozzolanic clasts. In the altar, apse, and aedicule, which constitute the principal place of the Mithraeum, a variety of materials used for the ornamental purpose are represented by pumices, travertine, marble, and limestone. The altar material, catalogued as marble, resulted in being a limestone coated with a white pigment.This work has been partially supported by the DEMORA (Grant No. PID2020-113391GB-I00) projects funded by the Spanish Agency for Research AEI (MINEICO/FEDER-UE). The authors wish to acknowledge professional support of the Interdisciplinary Thematic Platform from CSIC Open Heritage: Research and Society (PTI-PAIS)

SiO2 nanoparticles as new repairing treatments toward the Pietraforte sandstone in Florence renaissance buildings

In this work, the consolidation efficiency of SiO2 nanoparticles (synthesized in the Chemistry laboratories at the Tor Vergata University of Roma) was tested on Pietraforte sandstone surfaces belonging to the bell tower of San Lorenzo (Florence, Italy) and was fully investigated. Nanoparticles (synthesized in large-scale mass production) have been characterized by XRD—X-Ray Diffraction; Raman and FTIR—Fourier Transform Infrared spectroscopy; SEM—Scanning Electron Microscopy; while the Pietraforte sandstone morphology was examined by Porosimetry, capillary absorption test, surface hardness test, drilling resistance and tensile strength. The colorimetric measurements were also performed to characterize the optical modification exhibited by Pietraforte sandstones, especially after the SiO2 treatments. Our results show that applying to the Pietraforte, the new consolidating agent based on SiO2 nanoparticles, has several advantages, as they are more resistant to perforation, wear, and abrasion even long range (for long times of exposure and consolidating exercise against Florentine sandstone), compared to the CaCO3 nanoparticles (tested in our previous paper), which instead show excellent performance but only close to their first application. This means that over time, their resistance to drilling decreases, they wear much more easily (compared to SiO2 -treated sandstone), and tend to exhibit quite a significant surface abrasion phenomena. The experimental results highlight that the SiO2 consolidation efficiency on this kind of Florentine Pietraforte sandstone (having low porosity and a specific calcitic texture) seems to be higher in terms of water penetration protection, superficial cohesion forces, and an increase in surface resistance. Comparing the performance of SiO2 nanoparticles with commercial consolidants in solvents such as Estel 1000 (tested here), we demonstrate that: (A) the restorative effects are obtained with a consolidation time over one week, significantly shorter when compared to the times of Estel 1000, exceeding 21 days; (B) SiO2 nanoparticles perform better than Estel 1000 in terms of cohesion forces, also ensuring excellent preservation of the optical and color properties of the parent rock (without altering it after application)

Neutron Imaging and Learning Algorithms: New Perspectives in Cultural Heritage Applications

Recently, learning algorithms such as Convolutional Neural Networks have been successfully applied in different stages of data processing from the acquisition to the data analysis in the imaging context. The aim of these algorithms is the dimensionality of data reduction and the computational effort, to find benchmarks and extract features, to improve the resolution, and reproducibility performances of the imaging data. Currently, no Neutron Imaging combined with learning algorithms was applied on cultural heritage domain, but future applications could help to solve challenges of this research field. Here, a review of pioneering works to exploit the use of Machine Learning and Deep Learning models applied to X-ray imaging and Neutron Imaging data processing is reported, spanning from biomedicine, microbiology, and materials science to give new perspectives on future cultural heritage applications