Investigating the long-term performance of building materials, such as drying shrinkage, moisture expansion, creep, and others, usually requires long-lasting tests with a high number of specimens. Given the initial costs, required data acquisition systems, and the time allocated, conventional sensors like LVDTs become costly for such long-term experimental studies. This article proposes an innovative cost-effective solution combining optical microscopy imaging, 3D printed sliding rulers, and Python-based artificial vision to overcome these limitations. The 3D printed rulers establish a local physical reference frame, while the artificial vision system uses contour detection and point tracking of optical targets to quantify displacements. Unlike continuous monitoring systems, the proposed solution utilises a discontinuous point-tracking approach, allowing a single USB microscope to monitor an unlimited number of specimens while maintaining the possibility for moisture exchange between the material surface and the environment. The system was metrologically validated against a laser interferometer, achieving an expanded instrumental uncertainty of 0.0042 mm (4.2 & micro;m), determined through strict calibration. These results demonstrate that the proposed solution delivers accuracy comparable to conventional sensors but with significantly higher scalability and lower cost, making it highly suitable for extensive long-term experimental programmes.

This study presents a comprehensive in-situ investigation of dry-joint stone masonry walls across 23 vernacular buildings constructed with granite and schist in three rural villages. The proposed methodology integrates visualbased qualitative assessments (Masonry Quality Index - MQI and the Masonry Typology classification proposed by the Italian Building Code, MIT 2009) with non-destructive techniques (sonic pulse velocity, ultrasonic pulse velocity, and Schmidt hammer rebound testing). The MQI method enabled quantification of wall texture characteristics and classification under different load conditions, showing that schist walls generally exhibited higher quality scores. Mechanical properties, including compressive strength, elastic modulus, and shear strength were estimated based on both the MQI and MIT scores, revealing consistently higher values for schist masonry and demonstrating the sensitivity of MQI to geometrical and constructional features. Ultrasonic velocity tests confirmed material anisotropy in schist due to its mineral layering, while granite showed more isotropic behavior. Correlation analyses highlighted a strong positive relationship between the MQI and sonic velocity, validating the ability of the MQI to characterize the mechanical behavior of masonry assemblies. Significant correlations were also observed between the sonic velocity and masonry morphological features, such as the void ratio. These findings demonstrate that the adopted methodology offers a robust framework to provide meaningful mechanical estimations of dry-joint masonry walls.

Traditional stone masonry buildings were often the result of non-engineered processes, relying instead on traditional construction techniques developed by craftsmen and passed down through generations. Masonry is a composite material made of natural or manmade units and, when characterized by high quality workmanship, masonry units are arranged in staggered horizontal layers to avoid continuous vertical joints, with the mortar used to bind these units and promote a monolithic behavior. Furthermore, masonry buildings can exhibit a wide array of features in terms of bond patterns and material variety used in masonry panels assemblage. These characteristics complicate the process of systematically classifying masonry types. Indeed, stone masonry buildings can display inadequate performance in withstanding seismic load due to poor material properties (e.g. mortar quality) and construction details (e.g. round unshaped stones, absence of connection between walls leaves, presence of voids). The awareness of the scientific community towards the stereotomy applied in historical constructions has progressively grown over time. There have been studies evaluating how the presence or absence of through-stones, as well as spatial arrangement of stone-units influences overall performance of masonry walls under in-plane and out-of-plane loading. This work intends to provide an insight into the influence of masonry typology and masonry bond arrangements of stone masonry in the out-of-plane resistance, cracks and collapse mechanisms.

Managing cultural heritage has been significantly impacted by the integration of digital tools in recent times. These tools help organize information about cultural assets, develop conservation strategies, and promote cultural identity. Despite the benefits, the use of digital tools to create innovative applications for managing vernacular built heritage is still limited. To address this issue, this article introduces a methodology for creating a digital solution tailored for managing built heritage in vernacular settlements. This approach involves utilizing a database containing information on each building within a settlement, which is then integrated with a 3D model generated through photogrammetry in a Game Engine. This integration allows for interactive data analysis, virtual explorations, management tasks, and the dissemination of heritage information. When employed as an educational resource, it has the potential to enhance community engagement. Additionally, this adaptable solution can be customized to suit various scenarios for the preservation of this significant heritage. The practical use of this methodology is demonstrated through a case study of Pinheiro Novo, a village situated in the Montesinho Natural Park in north-eastern Portugal, showcasing the implementation advancements.

Depopulation in rural areas poses significant threats to the preservation of vernacular architecture, a key representation of a region's cultural and historical heritage. Across many rural regions of Southern Europe, depopulation has led to significant demographic and cultural shifts. In Portugal, this trend is evident in various interior regions, including the Bragança district where the population has decreased by approximately 47.4

This study investigates the out-of-plane behavior of two-leaf brick masonry walls under seismic-like loading through an experimental campaign involving three U-shaped wall specimens: an unstrengthened wall (UMW), a repaired wall (RMW) using Textile Reinforced Mortar (TRM), and a newly built, pre-strengthened wall (RMW_UND). Using airbag quasi-static loading and non-destructive testing methods (e.g., sonic testing), the structural response, damage patterns, and energy dissipation of each configuration were evaluated. Results show that TRM significantly enhances out-of-plane strength, ductility, and energy dissipation capacity. RMW_UND displayed a 93 % increase in lateral capacity compared to UMW, while RMW, despite its damaged conditions, achieved improvement of its performance. These findings validate the TRM solution selected as an effective option for both preventive strengthening and post-damage repair of existing masonry, particularly in seismicprone regions.

Vernacular built heritage, which is rich in cultural knowledge and identity, is increasingly threatened by modernisation. The absence of specific assessment tools, however, prevents a thorough evaluation of this impact. To address this gap, this paper presents a methodology for assessing how contemporary transformation processes affect the built heritage of vernacular settlements facing abandonment. This methodology involves inventorying the buildings of a vernacular settlement to identify alterations that significantly impact their vernacular character. Each building is assigned an index value quantifying the impact of these alterations. This process is facilitated by a multicriteria decision-making (MCDM) approach that incorporates the combined judgement and expertise of stakeholders typically involved in site management. The results yield an index that quantifies the preserved vernacular character of a site. Designed to be adaptable to diverse cultural contexts and situations, this methodology was implemented in thirteen vernacular villages within Montesinho Natural Park (MNP), Portugal, where buildings undergo continuous substitution, modification, and abandonment. This research offers policy-makers and site managers a replicable model for developing management strategies that can help safeguard and revitalise these unique heritage assets. This research hypothesises that enhancing vernacular building practices can reverse depopulation by fostering dynamic community engagement.

Unreinforced masonry structures are a significant percentage of the global building stock and are often vulnerable to seismic events due to their inherent structural weaknesses and limited deformation capacity. Although seismic codes promote regularity in structural design, achieving this in unreinforced masonry buildings is often a challenging task. Despite extensive research using shake table tests, quasi-static testing of unreinforced masonry buildings remains limited, particularly in the presence of plan irregularity and rigid diaphragm. The present study addresses this research gap by investigating the seismic response of a half-scale, two-story, unreinforced masonry building with plan irregularity through cyclic quasi-static testing. The experimental campaign presented here shows the findings from two tests, including dynamic identification. The first test indicated torsional amplification and rocking-induced wall detachment during the pre-peak response. These results prompted modifications to the experimental setup, including the addition of extra weight to prevent overall rocking and the repairing of the boundary interface to re-establish structural integrity for subsequent testing. The initial results highlight the influence of plan irregularity within the pre-peak behaviour and provide a basis for further exploration in the seismic assessment of irregular, unreinforced masonry buildings.

Salt crystallization, one of the key deterioration mechanisms, can cause significant damage to heritage structures over time. This study investigates the effects of salt crystallization on the physical, mechanical, and microstructural properties of two granite types with distinct pore characteristics. A comprehensive experimental campaign, including mercury intrusion porosimetry, capillary absorption, ultrasonic pulse velocity, uniaxial compressive tests, and digital image correlation, was conducted to evaluate the progression of salt-induced damage. Results from MIP, capillary absorption, and UPV primarily reflected the initial formation and growth of sodium chloride crystals within the pore network, highlighting their utility in capturing early-stage processes. Uniaxial compressive tests provided clear evidence of damage, revealing significant reductions in compressive strength and elastic modulus. The interplay between pore characteristics, crystallization pressures, and mechanical degradation revealed distinct damage behaviors in the two granite types. Granite with a capillary-active pore network showed greater susceptibility to salt crystallization, with a 55

Vernacular architecture in depopulating rural areas faces critical challenges due to climate change, particularly with the rise in extreme events like heat waves. These events threaten the conservation of buildings and the well-being of their inhabitants, especially in regions undergoing demographic decline and an aging population. The sustainability of these structures, built with traditional materials and techniques, raises important questions about their ability to withstand current and future conditions especially in dry and warm climates. This study explores the combined physical and social vulnerability of vernacular buildings exposed to heat waves, focusing on how architectural and sociodemographic factors influence the resilience of these structures and their inhabitants. Using a vulnerability index-based methodology and an on-site data collection, vulnerability levels across a variety of vernacular buildings and vulnerable households have been identified. The results emphasize how passive design features can help to mitigate the effects of extreme heat. At the same time, social factors worsen vulnerability, particularly for aging and low-income populations—common characteristics of many depopulating rural areas. This research underscores the importance of protecting the cultural and functional value of vernacular architecture, positioning it not only as a component of rural identity but also as a critical resource for climate adaptation.

Using additional binders such as hydrated lime in cement-based systems implies changes in the development of chemical processes such as hydration and carbonation, having a clear impact in the rheological and mechanical properties of the material. This paper aims to study the impact of different amounts of hydrated lime (0, 50 %, and 66.7 % of lime as binder by volume), different curing ages (from 7 to 180 days), and evolution of the exposure front for the chemical processes in cement-based mortars. Moisture diffusion and mercury intrusion porosimetry (MIP) were performed to obtain information related to porosity, while phenolphthalein and thermogravimetric tests allowed the determination of the carbonation rate and the analysis of the temporal evolution of C-S-H, AFm, AFt, portlandite, and calcium carbonate phases, respectively. The results evidenced that adding lime to cement-based mortars accelerated the carbonation rates at long-term. Cement-lime-based mortars exhibited a higher carbonation efficiency, as evidenced by significant increases in the calcium carbonate quantities compared to portlandite after 28 days of curing. However, at early stage, pure cement-based mortars showed a faster penetration of CO2 and subsequent carbonation due to the low amount of available portlandite and early exposure to an environment prone to carbonation.

The detrimental effects of salt in masonry structures manifest across two distinct levels: (i) impacting structural elements and (ii) influencing ornamental elements. The presence of salt in the material’s body (even a small amount) can significantly alter the hygric properties of the porous building materials. The presented paper focuses on the hygric properties of a commonly used granite masonry material from the Northern region of Portugal, particularly focusing on its response to the presence of sodium chloride (NaCl) salt. The evaluated properties include results from different experimental methods, including vacuum saturation tests, capillary absorption tests, and cup methods. Additionally, the ultrasonic pulse velocity (UPV) tests were also conducted on granite samples under different conditions (dry state, saturated with pure water, and saturated with a salt solution). Anisotropy in the vapor moisture movement within granite samples was evaluated along perpendicular and parallel directions concerning the rift plane. Results indicated that vapor moisture movement was more restricted through the direction perpendicular to the rift plane in comparison to the parallel direction. The formation of salt crystals within the pore network significantly influenced open porosity and vapor permeability, emphasizing the impact of salt attack on granite masonry. These findings contribute to a better understanding of the influences of salt on granite masonry structures.

According to EN 1996 Part 1-1, the flexural strength of masonry could be estimated based on information related mainly to the compressive strength of the mortar and the type of material of the unit. However, it is necessary to consider the impact of the interaction between components due to their physical characteristics, such as water absorption of the units and water retentivity of the mortar that may affect the bond between masonry components. Therefore, this paper evaluates the influence of the use of different types of mortar and units on the flexural strength parallel to the joints of masonry. For this, two types of mortar were considered: 1:1:6, and 1:0:5 (Cement: Lime: Sand), by volume. Regarding the units, two types of clay bricks of different geometric configuration (solid and frogged) were chosen. Thus, four combinations of units and mortar types were considered for the construction of the masonry wallets according to the guidelines indicated in EN1052-2. Flexural strength parallel to the bed-joints was tested according to EN1052-2, and compressive strengths of mortar specimens were controlled in accordance with EN1015-11 for the age of 90 days. In addition, characteristics of the units and water retentivity of mortars were also evaluated. The results showed that the compressive strength of the mortar is a significant factor if the failure occurs at the mortar bed-joint and not at the interface between components.

The physical properties of the units and mortar affect the bond between them, as well as the mechanical performance of the masonry. The initial absorption rate of brick units during the construction process can be influenced by its moisture content. This work aims at understanding the influence of different brick conditioning (without immersion in water, immersed for 1 -2 s, and immersed for 30 min) on the shear bond behavior of the unit-mortar interface and related key mechanical parameters. For this, an experimental campaign of shear tests on triplet specimens was designed by considering three premixed mortars commercially available in Portugal and one lime-cement designed mortar. The results suggest that, regardless of mortar type, shear bond properties generally show higher values when 30-min immersion time brick conditioning was applied. Furthermore, it was observed that the cohesion values of the premixed mortars, whose compressive strengths were similar, tended to be close to each other when the longest immersion time was considered.

The characterization of vernacular buildings is crucial for understanding the historical, social, and cultural significance of a community. These buildings reflect a collective memory and result from a long adaptation process to the local environment. Documenting them facilitates better decision-making regarding the preservation of their intrinsic values and long-term conservation. Unfortunately, depopulation processes in many areas threaten this invaluable heritage. Furthermore, this heritage is often overlooked due to a lack of awareness and appreciation by local authorities and residents. This paper presents a methodology for documenting and inventorying vernacular built heritage, with the main goal of contributing to promoting its valorization. The methodology integrates Information and Communication Technologies (ICT) with GIS tools to create large-scale inventories. Using the Montesinho Natural Park (Portugal) as a case study, the methodology facilitated the collection of data from over 2,000 buildings in 13 villages. The collected data was then used to characterize the vernacular built heritage of selected villages in terms of authenticity, conservation state, materials, construction systems, past interventions, present use, and occupancy. The findings of this study can serve as a valuable resource for developing inventories of vernacular buildings in rural areas, contributing to the protection of this distinctive architectural heritage.

Salt decay is widely recognized as one of the most common mechanisms for the deterioration of building materials in monuments, sculptures, and civil structures. Understanding how salt crystallization affects the integrity of historic structures is therefore essential. Numerical tools can be used for this purpose and for estimating the damage induced by salt crystallization; however, there is still a lack of standardized procedures for accurate simulation of this degradation mechanism. In this study, we critically review existing numerical models to identify their advantages and limitations. The considered primary balance equations, variable factors, constitutive laws, assumptions, test procedures, and boundary conditions are investigated in more detail to highlight essential features. This paper describes that numerical models are generally developed based on several simplifying presumptions, such as isothermal conditions, constant boundary conditions, and the presence of only one type of salt. The impact of hydraulic interface resistances in masonry assemblies of units and joints on the numerical analysis of salt crystallization remains unclear. Despite a general understanding of the mathematical problem, several challenges persist regarding the development of constitutive laws for salt mixtures. A more accurate and reliable predictive simulation for salt decay in masonry can be developed by addressing the open issues discussed in this paper.

Concerning the preservation of built cultural heritage, historical masonry buildings have reached a critical level of deterioration because of their age, which consequently makes their resistance against salt decay problematic. The present study aims to describe the influence of salt crystallization on granite stone materials, a prevalent material in historic masonry in Northern Portugal. The paper aimed to understand the material’s susceptibility to sodium chloride (NaCl) induced damage. A series of nondestructive and destructive experiments (such as ultrasonic pulse velocity measurements and uniaxial compression strength tests) were conducted on granite stone to evaluate its properties in response to the salt crystallization phenomenon. The internal structure and integrity of granite samples were evaluated before and after exposure to salt crystallization cyclic tests. For the wetting/drying cycles, the environmental conditions (temperature and relative humidity) were chosen based on realistic settings, with an emphasis on avoiding the use of severe circumstances. The ultrasonic wave propagation measurements showed indirect indicators of microstructural alterations. The changes in compressive strength aligned with the findings from the other test programs. The combined results of the experimental campaign contribute to a better understanding of how salt crystallization might influence the physical and mechanical characteristics of granite masonry.

Human-induced climate change has profound effects on extreme events, particularly those linked to global warming, such as heatwaves, droughts, and wildfires. These events disrupt ecosystems, emphasizing the imperative to understand the interactions among them to gauge the risks faced by vulnerable communities. Vulnerability levels vary primarily based on a community’s resources. Rural areas, especially in the Mediterranean region of Europe, are experiencing acute depopulation, creating a complex situation affecting various aspects of society, from economic declines to cultural heritage loss. Population decline in rural regions weakens resources, leading to the abandonment of built environments, fostering desertification, and elevating the risk of wildfires. Communities undergoing this deterioration process become exceptionally vulnerable, especially when dealing with and recovering from extreme natural phenomena. This review offers insights into the dynamics of these hazards and the predominant challenges in rural areas. By focusing on a topic that has received limited attention, the aim is to inform future research initiatives, ultimately improving risk assessment and mitigation strategies for these vulnerable communities.