Recent Insights into the Construction Material Decay in Cathedral of Cádiz (Spain): A Current Overview of Conservation Issues

Mineralogical and textural characterization of the natural stone in Cádiz Cathedral reveals a diverse range of carbonate lithologies with varying fabrics, porosity and decay susceptibility. The white oolitic limestone was identified as the most vulnerable material, particularly in upper structural elements such as vaults and roofs. Results confirm a significant marine influence on weathering processes, evidenced by the ubiquitous presence of halite, trona, gypsum, and nesquehonite across all lithologies and mortars. These salts drive granular disintegration, exfoliation, and crust formation. Their origin is attributed to a combination of marine spray, capillary rise, and the historical use of brackish water in mortar preparation. Analysis of pink crusts and saline efflorescences indicates complex interactions between environmental factors, atmospheric pollutants, and previous restoration materials. Mortar samples display high heterogeneity; modern interventions notably utilized Portland-type cements and historical pigments like lead white, which are often incompatible with original substrates. In the short term, the integration of microclimatic sensor networks with materials analysis will facilitate data-driven decision-making for the building’s preservation and, continued sampling will be essential to monitor salt dynamics in response to shifting temperature and humidity trends associated with climate change and the influx of tourists to the monument.