This research presents a new intervention methodology on arches and vaults of a Renaissance factory in the Colegio Santo Domingo de Orihuela (16th century) using 3D software LIDAR technology that verifies the execution process of the works studying the different charges states and structure behavior. This document aims to explain a working methodology in the monitoring of structural repair interventions in the architectural heritage, in the specific case of the replacement of traditional one-way timber joist frame slabs on structures of former, splay and groin arches between vaults. This involves the compilation and processing of two types of data: on the one hand, the analysis of the different load states to which the intervention is exposed in its different phases: initial, dismantling of the different layers of traditional construction and replacement by the new structural system; and, on the other hand, the graphic information provided by the photogrammetry techniques used to dimension and define the spatial position of the structural elements that have historically resolved the covering of the architectural space in this type of Renaissance solution. The different layers and demolished materials have been verified by analysing their constructive disposition, thicknesses, and dimensions of the elements that formed part of the initial construction system and their own weights. In addition, the new construction systems used in the restoration project generate a state of loads similar to the existing one. The LIDAR technology used in the research process provides graphic data of the spatial position of the arches and vaults studied in the different states of the construction intervention. The point clouds obtained are analysed by taking as reference fixed points (considered unalterable and infinitely rigid) of the refectory and the coordinates of the initial and final states are compared. The results show minimal variations between the two positions, which justifies the goodness of the construction methods used and the structural safety obtained in the complex. This methodology applied to arches and vaults in heritage architecture guarantees the control and recording of the movements produced in the process.

This work evaluates the effectiveness of various consolidating treatments applied to Pugliese tuff (Gravina Calcarenite). This type of stone has been used in numerous historic buildings in the Puglia area (southeast of Italy), which presents durability problems due to high porosity, low cohesion between clasts, and low mechanical resistance. Eco-friendly treatments that generate CaCO₃ have been selected, specifically bioconsolidant KBYO biological and lime water, which a priori are capable of consolidating without occluding the pores or reducing them excessively, thereby creating compounds similar to those contained in the stone and being respectful of the environment. Nano-sized treatments have also been tested, including nanosilica and nanolime, to compare results with eco-friendly treatments. The bioconsolidating treatment has been applied in two different ways, the usual way consisting of two applications a day for 7 days, as well as a double treatment that is applied in two batches of 7 days with a rest of 7 days between applications. Double treatment has shown a great improvement in consolidation compared to the usual 7-day application; this treatment has obtained the best results in both mechanical and petrophysical properties. This study not only demonstrates the effectiveness of the bioconsolidant but also expands eco-friendly conservation strategies to improve the preservation of historical structures built in calcarenite.

Bioconsolidation treatment using bacterial carbonatogenesis has been proposed as an environmentally friendly strategy for the efficient preservation of damaged stones, particularly suitable for carbonate stones. The study presented here deals with the evaluation of the performance of this treatment, applied to damaged carbonate stones in two historical buildings in Spain. The methodology applied in this research serves as a reference for future similar studies. Results showed significant improvement in the petrophysical and mechanical properties of the damaged stone following the treatment through the production of calcite and vaterite by the abundant carbonatogenic bacteria inhabiting the stone. These bacteria were able to effectively consolidate weathered areas if an adequate nutritional solution was employed, thereby augmenting the stone’s resistance, as evidenced by the Drilling Resistance Measurement System (DRMS). FESEM images showed calcified bacteria and calcified exopolymeric substances (EPS) consolidating stone minerals without blocking their pores. In addition to consolidation, this biotreatment improves the stone’s behavior against water absorption and increases the contact angle of water droplets without significant modifications in the pore size or diminishing vapor permeability. No color changes are observed. Overall, these results show that the application of the nutritional solution (M-3P) for in situ consolidation of different types of porous carbonate building stones is a highly effective conservation method, with no modification of the chemical composition of the treated materials.

We present a methodological approach for the representation, visualisation and analysis of three-dimensional (3D) models of meaningful details in stone reliefs provided by digital documentation tools and subsequent processing. For this aim, anthropomorphous shapes engraved on a flat stone slab found in Sierra de Fontcalent (Alicante) are studied. The object under consideration was located near two archaeological sites, Cova del Fum -a cave with presence of the Chalcolithic material (Lopez, 2010)- and the archaeological site of Fontcalent, with remains from different phases of occupation spanning from 7th-6th BC to the 20th century (Ximenez, 2012). In the last few years, the use of digital tools provided by new technologies and software development has left traditional work methodology behind (De Reu et al., 2014) while enabling the development of new approaches to both minimise heritage alteration and provide objective and accurate information (Lopez-Menchero, Marchante, Vincent, Cardenas, & Onrubia, 2017). 3D documentation allows recording of cultural heritage at a reasonable cost with precision and quality through digital photography and SfM (Structure from Motion) photogrammetry with specialised software (De Reu et al., 2013). In this project, recording and documentation with digital photography and automated photogrammetric techniques are applied to the Fontcalent stone slab for its digitisation and subsequent 3D representation. From the resulting model, a two-folded line of study is obtained. On the one hand, a Digital Elevation Model (DEM) is generated to study the microtopographies of the stone with geographic analysis techniques provided by Geographic Information Systems (GIS) from different lighting conditions and surface reflections, which are calculated by hillshading or LRM (Local Relief Model) for the interpretation of the object (Carrero-Pazos, Vilas, Romani, & Rodriguez, 2014; Gawior, Rutkiewicz, Malik & Wistuba, 2017). On the other hand, from both the 3D model and the point cloud, the study is completed with the application of the methods of analysis and visualisation based on the Morphological Residue Model (MRM) which stands out every single detail of the surface morphology of the object (Caninas, Pires, Henriques, & Chambino, 2016; Correia, Pires, & Sousa, 2014). Further visualisations are based on Reflectance Transformation Imaging (RTI) which provides different shadows and reflections over the object from the application of a multidirectional illumination (Happa et al., 2010; Malzbender, Gelb, Wolters, & Zuckerman, 2000; Mudge et al., 2010). The results thus obtained of the Fontcalent stone slab allow us to visualise several characteristic elements. The anthropomorphous figure awaking interest is also combined with the figure resulting from different visualisations applied with GIS techniques which may resemble a zoomorph. The use of visualisation techniques shown in this study has been fundamental in order to recognise the latter element. The composition reveals a zigzag line already appreciated before the study so that it is interesting to check if visualisations based on GIS techniques are able to highlight it though being shallow incisions. In our experience regarding this study, visualisation by using the hillshading technique shows a greater level of 3D detail than that provided by the application of the sky-view factor technique which offers a flattering view. However, the former technique may occasionally show shadows which hide other details, unlike the latter technique which plots the entire slab surface illuminated while differentiating the associated microtopography on the basis of its marks. The use of shaders in combination with hillshading and particularly combined with high pass filtering, contributes to improving the visualisation and accuracy of shadowed areas. As a result, we conclude that the results obtained in this work by lighting techniques with GIS add a greater level of detail in comparison to those provided by the mesh or the point cloud. The study of the Fontcalent stone slab paves the way for two working hypotheses to be developed: on the one hand, its anthropological origin possibly related to the Chalcolithic, and on the other hand, its study as natural geological formations with ichnofossils. The digitisation of cultural heritage with available 3D technologies should be a mandatory requirement when facing any study, analysis or intervention. With the current development of such techniques, we have verified their contribution to fundamental characteristics in the corresponding stages of visualisation and study. Thus, the proposed methodology is presented as an accurate and complete alternative for the study and analysis of the existing cultural heritage, and opens new ways for the revision, reinterpretation and revaluation of the previously evaluated heritage through traditional techniques.

The Santo Domingo Diocesan School (Orihuela, SE Spain) is a singular case study that relates air quality monitoring and stone conservation. The monument suffers severe damage due to salt crystallization by rising damp, which is related to the indoor environment dynamics, high groundwater salt content, and microstructure, the building’s porous stone (biocalcarenite). Results revealed that ²²²Rn concentration in indoor air is low due to the building’s high ventilation rate, despite the medium-low geogenic radon potential in the area. Wavelets analysis showed that ventilation is caused by outdoor and indoor temperature variations and directly affects the ²²²Rn and CO₂ dynamics inside the church. CO₂, as well as relative humidity (RH), presented periodicities with intermediate frequencies (5–8 days) related to visits. These RH and temperature (T) variations intensified the salt damage by increasing the frequency of dissolution-crystallization cycles. The mineralogical characterization and geochemical calculations concluded that chlorides (halite and sylvite), sulfates (thenardite, epsomite, hexahydrite and aphthitalite) and nitrates (niter) present from dissolution forms to whiskers and hopper-type morphologies. This indicates high saturation values and, therefore, higher crystallization pressure values within the porous media of the biocalcarenite. On the contrary, the near-equilibrium crystal shape and incongruent precipitation reaction for humberstonite suggest a lower alteration for this salt on the building stone.

This work provides new data on the church of Nuestra Señora de la Asunción in Biar, combining the investigation of documentary sources with the analysis of the geometry obtained using LiDAR technology and the study of stone materials. This monument has a Proto-Renaissance façade of great architectural value, as it was the first building in the province of Alicante, in Spain, to use Renaissance decorations at the beginning of the 16th century. Its main façade reflects the four centuries of its construction from the 15th to the 18th centuries. The building has been digitised using LiDAR technology and photogrammetry. The graphic representation of the point cloud obtained from the aforementioned techniques makes it possible to study deformations in colour gradient with respect to a reference plane. The results obtained after the analysis of these data show that the method used in this work has served to detect and corroborate the constructive evolutions of the church obtained from the documentary sources investigated. This work serves as an example for similar works, proposing the incorporation of the analysis of anomalies in the geometry of the facings as a new variable that should be considered to complement the rest of the usual studies, bringing to light deformations and irregularities that at first sight may go unnoticed.