Ultrasonic waves behavior on Mauá Granite for the conservation of Monumento às Bandeiras

Abstract

The Monumento às Bandeiras by Victor Brecheret is constituted of Mauá Granite. It is a symbol of the city of São Paulo and a masterpiece by one of the most important Brazilian artists. This study aimed to assess the conservation status of this monument by using the non-destructive method of propagation of ultrasonic waves. The assessment was carried out considering the importance of this monument, which represents a significant period of São Paulo history, and mainly to contribute to its conservation by using a geological approach. In this study, the values of the P-wave velocities in the monument were compared with the values obtained in the laboratory sample, which was collected in the original quarry of the same stone as the monument. Appropriate methodologies were used in this study to obtain the values of velocities in laboratory and in situ. Three types of transmission were used: direct, semi-direct and indirect, with three different transducer pairs: 54 and 150 kHz and and exponentials of 54 kHz. Only the 54 kHz and 150 kHz transducers were compatible to the study of the monument using direct and indirect transmissions. The result of these evaluations indicates that the Monumento às Bandeiras is still in good conservation condition, based in the P-wave velocities: ca. 4.6 - 5.3 km/s, obtained directly in the monument, varying according to the type of transmission applied, and 5.2 - 5.6 km/s in the laboratory tests. These values are in accordance with non-altered granites.