Acoustic characterization and imaging of degradations of stones for the conservation of built and statuary heritage

Encadrement

• Directeur : Cédric Payan / LMA
• Directeur : Philippe Bromblet / CICRP (Centre Interdisciplinaire de Conservation et de Restauration du Patrimoine)

Abstract : In built heritage, some calcareous stones exposed to rain and runoff develop significant deteriorations which affect the material on several centimeters thickness. The variations of mechanical behavior with the water content could play a decisive role in these decay processes undergone by stones in cultural heritage. Regarding statuary heritage, some marble sculptures exposed to environmental conditions also develop deterioration over time. The effects of water are less significant, however thermal cycles could induce degradations, even at low levels (40°C – 60°C). This project focuses on 2 aspects: - characterization and understanding of the decay processes in built and statuary heritage from experiments carried out on calibrated samples conditioned in controlled hydric and thermal states. The evolution of the mechanical parameters will be followed by a non-destructive technique (linear and nonlinear resonance) by varying the water content of calcareous samples and the temperature of marble samples. - in situ acoustic imaging of existing works of art, taking into account the requirements of heritage conservation (non-contact measurements). The method is based on photogrammetry to reconstruct the acoustic image thanks to a 3D geometric model of the work of art. Linear and nonlinear parameters will be imaged and images will be analyzed in the light of the results of the first part.

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