Analytical tools applied to the evaluation of the influence of different marine environments on the conservation state of building materials

Abstract

Marine aerosol is a chemical complex system formed by inorganic salts and organic matter, together with airborne particulate matter from the surrounding environment. The primary particles transported in the marine aerosol (PMA) can experiment different chemical reactions in the atmosphere, promoting the so-called Secondary Marine Aerosol (SMA) particles. These kinds of particles, together with the natural crustal or mineral particles and the metallic airborne particulate matter emitted by anthropogenic sources (road traffic, industry, etc.) can be deposited on building materials from a specific construction following dry deposition processes. Apart from that, the acid aerosols (e.g. CO2, SO2, NOX, etc.) present in modern urban-industrial environments, coming also from anthropogenic sources, could be deposited in the buildings following dry or a wet deposition mechanisms. The interactions of these natural and anthropogenic stressors with building materials can promote different kind of pathologies.In this PhD work, the negative influence of different marine environments (direct or diffuse influence), with or without the influence of an urban-industrial area (direct or diffuse), on the conservation state of two historical constructions and some newly built houses from the Basque Country (north of Spain) was evaluated. These constructions include a wide variety of building materials (sandstones, limestones, artificial stones, bricks, plasters, cementitious materials, etc.). The analytical methodology applied for this purpose involved, in some case studies, the use of non-invasive portable/hand-held spectroscopic technique (ED-XRF and Raman spectroscopy) able to perform an in situ screening in order to extract preliminary results. After that, non-invasive spectroscopic techniques (micro-Raman spectroscopy, FT-IR, XRD, -ED-XRF, SEM-EDS), together with destructive techniques (ICP-MS and ion chromatographic), thermodynamic modellings and chemometric tools was also applied to extract the final conclusions about the pathologies identified on the constructions under study in relation with the specific marine environment where they are located.Thanks to the use of these analytical tools, it was possible to characterize different deterioration processes caused mainly by the influence of marine aerosol (wet and dry deposition), infiltration waters, birds droppings, salts migrations, atmospheric acid gases impact, biological colonizations, etc. Moreover, the characterization of the PMA particles and SMA particles was conducted, thanks to the development of a home-made passive sampler in the last case. Additionally, the deposition of this kind of particles on sandstone, following dry deposition processes, was also confirmed.