Multianalytical approach to study the dissolution process of weathering steel: The role of urban pollution

• Three weathering steel sculptures exposed to an urban atmosphere were studied.
• Several salts were identified by Raman spectroscopy over the steel surface.
• Salts were formed by reaction of pollutants with atmospheric particles and steel alloy.
• PCA analyzes confirm the correlation between the orientation and the degradation.
• The nickel is the most lixiviated metal of the alloy.

Weathering steel, in spite of its resistance against the atmospheric corrosion can be damaged due to the affection of environmental stressors. In fact, the presence of soluble salts formed after greenhouse acid gases impact, can accelerate the corrosion process. In this work three weathering steel sculptures exposed to urban atmosphere were studied. Portable Raman assisted by reflectance infrared spectroscopy, micro X-ray fluorescence and ion chromatography were used to diagnose the decaying process suffered by these structures. The role of calcium sulfate formed in situ upon the reaction of SO2 with calcite particles deposited on the surface of the sculptures was studied.