Correlation between ultrasonic measurements and mechanical testings: a methodology applied to D'Amico Palace of Milazzo

摘要

This research is a part of a diagnostic work that was carried out on Palazzo Marchesi D'Amico of Milazzo in Sicily. The results of the diagnosis are now going to be used as base for the conservation project. Aim of this work is to find correlation between the results of ultrasonic measurements obtained on two columns of the palace and the mechanical characteristics of constructional materials, taking also into account their anisotropy, in order to obtain information on the mechanical behaviour of the two columns in a non destructive way. The constituent materials of the columns are sandstone, of a type called in Sicily "arenaria". The material was analysed by means of the following analytical techniques: X Ray Diffraction, observation of cross sections under the optical microscope, analysis at the Scanning Electron Microscope. Longitudinal velocity at the frequency of 50 KHz was measured on three sections at different heights of the two columns. A tomography analysis was done on a section of a column. Since it was not possible to take sample from the columns to carry out the mechanical testing, were founded a cave from which was token three different blocks of arenaria that was similar, but non equal of course with respect the material of the columns. The difference was detected both by ultrasonic measurements and by petrographycal observations. Compression mechanical tests have been performed on the material of the cave and static and dynamic modules (obtained at 1 MHz) were compared. This study is devote to set up a suitable methodology for studying the mechanical behaviour of the material of the analysed particular of the monument, to apply when it is not possible to carry out mechanical testing directly on the same material and to optimise the number of tests on the same material, considering the low availability of materials in the conservation activities.