Nonlinear acoustic characterization of Carrara marble degradation under thermo-hygric cycles

Marie-Laure Chavazas (1, 2) , Philippe Bromblet (2) , Jérémie Berthonneau (2) , Cédric Payan (1)

1 LMA - Laboratoire de Mécanique et d'Acoustique [Marseille]
2 CICRP - Centre Interdisciplinaire de Conservation et Restauration du Patrimoine

Carrara marble is a widely used type of marble, in buildings and in sculptures, in ancient and in recent works. Yet, some buildings and sculptures made in marble and exposed to environmental conditions can develop deteriorations over time, such as bowing, cracks, expansion, reduction of mechanical strength. Previous studies have shown that these degradations can result from exposure to temperature variations. Even cycles at low temperatures (40 - 60 °C) can lead to significant damage. Moreover, the above-mentioned deteriorations can be enhanced by the combination of variations of temperature and relative humidity. This study is therefore focused on the characterization and the understanding of these degradation mechanisms from laboratory experiments on calibrated samples of Carrara Gioia marble under controlled temperature cycles at various temperatures between 40 and 500 °C. In addition, samples are also characterized along cycles of adsorption/desorption. The evolution of the mechanical state of the samples is followed by a non-destructive nonlinear acoustic technique: Nonlinear Resonant Ultrasound Spectroscopy (NRUS). An NRUS test consists in measuring the resonance peak and the deformation of the studied sample for several increasing amplitudes of excitation. The nonlinearity parameter can then be calculated. It is related to damage and heterogeneity of the sample at the microscopic scale. The evolution of resonant frequency (measured at low amplitude of excitation) is also studied. The variation of the NRUS parameters with temperature is eventually compared to the evolution of the microstructure of the samples (opening of grain boundaries, microcracks, etc.) through observations at the microscopic scale, such as thin sections and X-ray microtomography.

Mots clés: nonlinear resonance; thermo-hygric weathering; Carrara marble; heritage conservation

Domaines: Acoustique [physics.class-ph]

Marie-Laure Chavazas, Philippe Bromblet, Jérémie Berthonneau, Cédric Payan. Nonlinear acoustic characterization of Carrara marble degradation under thermo-hygric cycles. 5th International Conference on Innovation in Art Research and Technology, Jun 2022, Paris, France. ⟨hal-04553242⟩