Dynamic elastic characterization of carbonate rocks used as building materials in the historical city centre of Cagliari (Italy)

Abstract

This paper focuses on the dynamic characterization approach to evaluate the conservation\ud state of carbonate building stones of monumental structures. In particular, we report the use of\ud elastic waves at an ultrasonic frequency of 54 kHz to define quantitatively some dynamic properties\ud of carbonate rock types used as building materials. Measurements of compressional and shear wave\ud velocities have been carried out and the relationship between some physical properties of the investigated\ud rocks and these geophysical measurements have been evaluated. The ultrasonic data were also\ud supplemented by a petrographical study of these rocks to correlate their petrophysical features with the\ud elastic ones. Based on the results of the laboratory measurements, in situ applications on a significant\ud monumental structure have been also carried out to check zones of weakness and to assess the state\ud of deterioration of the investigated stones. A comparison of laboratory and in situ results confirms that\ud dynamic characterization is a useful approach

Three-dimensional imaging from laser scanner, photogrammetric and acoustic non-destructive techniques in the characterization of stone building materials

“…5). In the lower part of the pillar the ashlars are made of Pietra Forte, a very tenacious and compact organogenic limestone, classified as boundstone according Dunham (1962), with porosity of about 1 %-4 % (Cuccuru et al, 2014). In its upper part, the pillar is made of ashlars of Pietra Cantone, a bioclastic mudstone or wackestone (Duhnam, 1962), with a porosity up to about 25 % (Cuccuru et al, 2014).…”

Characterization of Rock Samples by A High-Resolution Multi-Technique Non-Invasive Approach

“…The 3D tomography was carried out for a fine characterization of the samples in terms of elastic properties and in order to determine size and location of potential defects, cracks, fissures and cavities in their inner part. As a matter of fact, as recognized in previous works [8,26,27,45,[84][85][86][87] rock texture, different type of porosity, compositional heterogeneities, and presence of fractures play an important role in ultrasonic measurements and greatly influence the elastic behaviour of the rocks. The great volume of ultrasonic data from the 3D tomography allows a much better understanding of the three-dimensionality of possible defects, fractures and heterogeneities inside the samples.…”

“…The Pietra Forte is a very consistent and tenacious carbonate rock, widely used in the past to build monumental structures and the ancient city walls of the town of Cagliari [26,69].…”

“…Some techniques such as the Terrestrial Laser Scanner (TLS) [19] and fluorescence LIDAR [20] are very useful to analyse the shallow parts of stone materials. Other non-invasive geophysical techniques such as magnetic resonance imaging (MRI) [21] and infrared thermography (IRT) are useful to probe just below the surface materials [22,23] while ultrasonic techniques penetrate inside the materials [24][25][26][27]. Variations in ultrasonic wave propagation velocity and amplitude are related to rock internal structure changes [28].…”

“…In the second step of this workflow, based on the 3D models from previous techniques, a 3D ultrasonic tomography on each rock sample was accurately planned and carried out. The use of information based on the propagation of ultrasonic signals through the investigated materials represents one of the most common approaches across all scales for the elastic-mechanical characterization of rocks [26,[39][40][41][42][43][44]. The ultrasonic methods have a wide spectrum of applications both in situ and in laboratory producing higher resolution results [45][46][47][48].…”