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Efflorescence in buildings: analysis and diagnosis of construction pathologies
Wed 17/09/2025 - 17:51
Efflorescence represents one of the most frequent pathologies in the facades of modern buildings. These whitish stains, although apparently minor, can indicate underlying problems that compromise both the aesthetics and the structural integrity of the buildings.
What is Efflorescence?
Efflorescence is a phenomenon that manifests itself when soluble salts present in construction materials migrate to the surface due to the presence of moisture. When the water evaporates, these salts crystallize forming the characteristic white veil that we observe on walls and facades.
Although in most cases the problem is purely aesthetic, efflorescence can generate internal tensions that cause the disintegration of the material, especially when aggressive salts are involved in porous coatings.
Efflorescence diagnostic methodology
At SOCOTEC we apply a rigorous methodological approach to efflorescence analysis, focusing on two fundamental aspects:
- Deposition pattern: How and where salt is deposited on the surface
- Chemical composition: Accurate identification of detected salts using advanced analytical techniques
This methodology allows us not only to identify the source of the problem, but also to propose effective preventive solutions.
Case Study
Localized efflorescence in stone cladding
In a recent investigation, we identified a case of localized efflorescence in the joints of stone plates, specifically at the height of the fastening clips. The pattern presented a trickle appearance, where the salt-laden water descended by gravity generating visible white spots.
Technical analysis of efflorescence
The analysis by X-ray diffraction confirmed that the salt was composed mostly of calcium carbonate (CaCO₃).
During the technical inspection, the following factors were identified:
- Brick masonry wall coated with mortar
- Fixing of plates with steel staples and adhesive cement with high cement content
- Deficiencies in the crowning pieces that allowed rainwater infiltrations
EFFLORESCENCE
Mechanism of Pathology
The process of efflorescence formation in this specific case followed a complex and sequential mechanism that began with the infiltration of rainwater through the deficiencies detected in the crown of the wall. Once the water managed to penetrate the construction system, it began a process of dissolution of the portlandite (Ca(OH)₂) present both in the cladding mortar and in the adhesive cement used to fix the stone slabs.
During its downward journey along the back of the plates, the water loaded with dissolved salts encountered an obstacle in the steel staples that served as fasteners. This impediment caused part of the flow to be diverted to the outside, channeling through the joints between the stone slabs, where the water loaded with portlandite reached the outer surface of the cladding.
Contact with external environmental conditions triggered the surface evaporation process, which in turn caused the crystallization of the previously dissolved portlandite. However, the process did not end at this stage, as the portlandite crystals subsequently reacted with carbon dioxide (CO₂) present in the atmosphere, giving rise to a carbonation process that resulted in the formation of calcium carbonate (CaCO₃). This final compound visibly manifested itself as the characteristic whitish efflorescence spots that presented the distinctive drip pattern observed on the façade of the building.
The process of efflorescence formation in this specific case followed a complex and sequential mechanism that began with the infiltration of rainwater through the deficiencies detected in the crown of the wall. Once the water managed to penetrate the construction system, it began a process of dissolution of the portlandite (Ca(OH)₂) present both in the cladding mortar and in the adhesive cement used to fix the stone slabs.
During its downward journey along the back of the plates, the water loaded with dissolved salts encountered an obstacle in the steel staples that served as fasteners. This impediment caused part of the flow to be diverted to the outside, channeling through the joints between the stone slabs, where the water loaded with portlandite reached the outer surface of the cladding.
Contact with external environmental conditions triggered the surface evaporation process, which in turn caused the crystallization of the previously dissolved portlandite. However, the process did not end at this stage, as the portlandite crystals subsequently reacted with carbon dioxide (CO₂) present in the atmosphere, giving rise to a carbonation process that resulted in the formation of calcium carbonate (CaCO₃). This final compound visibly manifested itself as the characteristic whitish efflorescence spots that presented the distinctive drip pattern observed on the façade of the building.
"This case study reflects SOCOTEC's commitment to the rigorous analysis of construction pathologies. Our goal is to offer clients and professionals in the sector solid technical solutions that guarantee the durability of the materials and the quality of the buildings, minimizing risks and preserving both the aesthetics and the structural integrity of each project."
This case study was presented at the IX International Workshop on Crystallization in Porous Media, CRYSPOM, held in Barcelona on September 17-18, 2025, demonstrating our commitment to research and scientific advancement in the diagnosis of construction pathologies.SOCOTEC Comprehensive Solutions
SOCOTEC Comprehensive Solutions
At SOCOTEC, we don't just identify the visible symptoms of efflorescence. Our comprehensive approach includes:
- In-depth analysis of the causes that generate the pathology
- Sound technical criteria based on proven methodologies
- Solutions aimed at guaranteeing the durability of materials
- Expert support throughout the diagnosis and correction process
AUTOR
Jose Carlos Morgado Sánchez,
Structural Studies Technician of the Quality Control Unit of SOCOTEC
Contact us and let us help you protect the quality and durability of your project.
At SOCOTEC we offer developers, construction companies and owners all our experience in the analysis of construction pathologies. If your building has stains, dampness or other similar symptoms, our technical team can help you identify the causes and propose the most appropriate solution.
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