Search Results (2)

The crystallization of soluble salts is one of the most significant agents of deterioration affecting porous building materials in historical architecture. This process not only compromises the physical integrity of the materials but also results in considerable aesthetic, structural, and economic consequences. Soluble salts involved in these processes may originate from geogenic sources—including soil leachate, marine aerosols, and the natural weathering of parent rocks—or from anthropogenic factors such as air pollution, wastewater infiltration, and the use of incompatible restoration materials. This study examines the role of capillary rise as a primary mechanism responsible for the vertical migration of saline solutions from the soil profile into historic masonry structures, especially those constructed with calcareous stones. It describes how water retained or sustained within the soil matrix ascends via capillarity, carrying dissolved salts that eventually crystallize within the pore network of the stone. This phenomenon leads to a variety of damage types, ranging from superficial staining and efflorescence to more severe forms such as subflorescence, microfracturing, and progressive mass loss. By adopting a multidisciplinary approach that integrates concepts and methods from soil physics, hydrology, petrophysics, and conservation science, this paper examines the mechanisms that govern saline water movement, salt precipitation patterns, and their cumulative effects on stone durability. It highlights the influence of key variables such as soil texture and structure, matric potential, hydraulic conductivity, climatic conditions, and stone porosity on the severity and progression of deterioration. This paper also addresses regional considerations by focusing on the context of Spain, which holds one of the highest concentrations of World Heritage Sites globally and where many monuments are constructed from vulnerable calcareous materials such as fossiliferous calcarenites and marly limestones. Special attention is given to the types of salts most commonly encountered in Spanish soils—particularly chlorides and sulfates—and their thermodynamic behavior under fluctuating environmental conditions. Ultimately, this study underscores the pressing need for integrated, preventive conservation strategies. These include the implementation of drainage systems, capillary barriers, and the use of compatible materials in restoration, as well as the application of non-destructive diagnostic techniques such as electrical resistivity tomography and hyperspectral imaging. Understanding the interplay between soil moisture dynamics, salt crystallization, and material degradation is essential for safeguarding the cultural and structural value of historic buildings in the face of ongoing environmental challenges and climate variability. Full article

The application of non-contact diagnostic methodologies is the current challenge in the frame of the cultural heritage, referred to as preservation, monitoring and restoration. Inspired by the potential shown by infrared thermography in rock mechanics’ non-destructive applications, this paper presents the results achieved by its use for the quick survey of different weathering types affecting natural stones at historical buildings. Infrared thermography allowed recognizing and mapping the different surface temperatures arising from the presence of efflorescence, subflorescence, alveolization, black crusts and bioweathering at limestone and basalt stones. Infrared data were sided by photogrammetric three-dimensional models of surveyed spots, which provided quantitative data on the thickness of rock affected by mechanical weathering, and key correspondence between the two techniques is highlighted. Achieved results show that infrared outcomes are related to different aspects primarily involving the stone face morphology and color, as well as the environmental conditions at the surveying time. Provided interpretations were validated by field visual inspections, which confirmed the good potential of infrared thermography as a quick weathering diagnostic tool. This study can be therefore considered a starting reference for knowledge development in this scientific field. Full article