Weathering of limestone after several decades in an urban environment

• The chemical and physical parameters of limestone exposed during more than 60 years in an urban environment are characterized at different scales.
• From a chemical point of view, the alteration leads to an in-depth sulfur enrichment neoformation of gypsum and to a surface carbon deposit.
• The weathering rate is highly dependent on the position of the block on the monument.

The alteration of “Saint-Maximin Roche fine” limestones exposed to the Parisian urban environment during more than 60 years has been studied. It leads to changes of the texture and morphology, to the neo-formation of gypsum on the subsurface and to the deposition of carbon containing phases on the surface. Depending on the location of the blocks on the monuments, the alteration states are different related to different water activities that could influence the further alteration processes. The multiscale characterization has enabled to correlate the macrometric properties to the mesoscopic behavior, what is essential to understand the alteration mechanisms.