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Ray velocity plotted against travel path in combination with the classification of decay after Köhler (2014). The various colours and shapes of the data points depict the transmitter positions on the sides of the obelisk
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The use of ultrasonic methods for a non-destructive investigation of immovable, high-ranking cultural heritage, landmark buildings, and sculptures made of natural stone, has developed into the state-of-the-art testing throughout the last 20 years. This routinely applied transmission method gives information about the rock as a whole, but no detaile...
Citations
... Degradation of marble is mainly related to the excessive anisotropic thermal expansion of carbonate crystals [90]. Artificially eroded specimens produced by heating fresh Carrara marble at 400˚C for 1 hour exhibit widespread microcracks at grain boundaries, just like naturally decomposed samples. ...
... In the absence of a multiparameter inversion workflow, one option is to invert V v and freezing a degree of anisotropy during all the optimization. For instance, Menningen et al. (2018) did ultrasonic measurements in marble samples, the ray-based approach of Jackson and Tweeton (1996) under the elliptical assumption was used in a single-parameter inversion of V v while a degree of anisotropy remained constant ( = const) and knowing that V h = V v √ 1 + 2 , they presented a model with 20% of anisotropy that explained the observation better than the isotropic inversion. Although we could also do the same, we go directly to our multiparameter workflow because the fixing of anisotropy is a big assumption that might certainly introduce errors. ...
A novel traveltime tomography approach has been developed to invert both velocity and anisotropy restricted to 2D geometry. The fundamental equation whose solution gives us the first-arrival traveltimes between a source and a receiver is the Eikonal equation, which becomes more complex when anisotropy is considered. In order to solve the Eikonal, an Eulerian formulation based on element-discretization discontinuous Galerkin method is adopted. The use of a direct solver allows us to obtain the total solution of the Eikonal, this includes diffraction events that may occur in the presence of large-velocity contrasts, while the widely used ray solution does not include these events. For the inverse part, an iterative local gradient-based optimization is chosen, where a least-square misfit function between picked and synthetic traveltimes need to be minimized. Contrary to other tomography approaches that usually compute the expensive sensitivity matrix, we avoid this computation by using the adjoint-state method. The adjoint formulation allows us to obtain the gradient efficiently by solving a transport equation that propagates the residuals from receivers to each source location, thus describing the sensitivity of the data to the model. We have developed a workflow that includes model regularization and data-weight matrix. Anisotropy is obtained under the elliptical assumption, thus two parameters are inverted simultaneously with an optimal parametrization that includes vertical and horizontal velocities, this choice being driven by a sensitivity analysis and synthetic examples. The code was used for active seismic and electromagnetic data acquired in carbonates both at the field and laboratory scale with different acquisition configurations. A first example concerns crosshole GPR acquisitions performed at the field scale within the Laboratoire Souterrain à Bas Bruit (LSBB) facilities, where the presence of a deep gallery makes the inversion challenging. In this weak anisotropy environment, the results are confronted to full wave inversion results and to geological data. At the laboratory scale, a multi-physics acquisition including seismic and GPR data was tested on a cubic rock sample. It underlines some issues related to the size of the sources/receivers compared to the dimension of the sample, which must be tackled before considering any inversion. Then, the datasets are inverted and velocity/anisotropy images are obtained and discussed in terms of heterogeneity and potential localized fractures.
... V p is increasingly used to characterize the weathering condition of marbles. Based on experimental work, Köhler [40] established a damage classification which have been an important tool for numerous authors working in the field of deterioration and conservation of marble [41][42][43][44][45][46][47][48][49]. The damage classes, marble condition and threshold V p values commonly used are shown in Table 1 [41][42][43][44][45][46][47][48][49] and were adopted for this study. ...
... Based on experimental work, Köhler [40] established a damage classification which have been an important tool for numerous authors working in the field of deterioration and conservation of marble [41][42][43][44][45][46][47][48][49]. The damage classes, marble condition and threshold V p values commonly used are shown in Table 1 [41][42][43][44][45][46][47][48][49] and were adopted for this study. The terminology to describe the marble condition varies but in most cases the connotations of the terms are identical. ...
The effects induced by diammonium hydrogen phosphate (DAP) on coarse marble varieties susceptible to granular disintegration as consolidation material is still poorly addressed. The work aims at investigating the behavior and efficacy of diammonium hydrogen phosphate(DAP)-based consolidant prepared in laboratory onto weathered coarse-grained marbles and, in the process, to unveil if the treatment investigated is a possible option to consolidate Trigaches marble elements from Roman Villa of Pisões.
Sound, artificially and naturally weathered coarse marble samples were used for the purpose. The condition of naturally weathered marble slabs was assessed to reproduce artificially aged samples and used for testing the efficacy of DAP consolidant. Naturally weathered slab fragments showed a uniform damage in depth, an increased porosity and water absorption, and very similar conditions were successfully achieved in laboratory by heating sound marbles up to 300 °C for 1 h.
DAP consolidant has low viscosity and can easily penetrate within the porous structure of coarse marble in granular disintegration. It promotes the formation of new calcium phosphate phases with binding capabilities that partially restore cohesion in-depth. Alteration of the color was negligible which is also a positive characteristic.
Pilot tests in naturally weathered marbles revealed some interference of superficial bioorganisms residues in the absorption of DAP, however this was able to treat the entire thickness of the slab fragments, improving its cohesion state to an acceptable or good condition.
Good correlations between the results of artificial aged samples with those of naturally weathered marble were achieved and the DAP-based treatment revealed to be an effective option to consolidate Trigaches marble elements from Roman Villa of Pisões.
... The correlation of the P-wave velocity determined by ultrasonic measurements and the weathering state of marble was confirmed by many scientific analyses (Ahmad et al. 2009;Babacan and Gelisli 2015;Boudani et al. 2015;Dürrast et al. 1999;Fleischer 2002;Köhler 1991Köhler , 2014Lindner et al. 1999;Menningen et al. 2018a, 2018b, 2019, Rüdrich 2003Rüdrich et al. 2013;Siegesmund et al. 2000a;Siegesmund et al. 2004b;Weiss et al. 1999;Weiss et al. 2002a). Whereas the P-wave velocity of a quarry fresh marble is relatively high [6-7 (km/s)], it decreases with increasing weathering state. ...
Marble as ornamental and dimensional stones as well as in their natural environments show complex weathering phenomena. Physical, chemical, and biological weathering of marble are well documented. The impact of climate change on monuments and historic buildings in terms of modeling and predicting future scenarios requires new approaches to forecast the ongoing decay in the near and far future. Ultrasonic wave velocities are a powerful and sensitive tool for the damage assessment of marble. For a maximum porosity of up to 1%, ultrasonic wave velocities (P-wave velocities) are ranging between 1 km/s and over 6 km/s. Water saturation has an important influence on the magnitude and directional dependence of ultrasonic wave velocities together with the mineralogical composition and the rock fabrics. Ongoing experimental alteration approaches were used to document the state of deterioration using Vp-systematics. In addition, thermal expansion and the residual strain values after applying thermal impacts were used to introduce a new quantitative measure based on experimental length changes and volume changes. To quantify such volume changes, a so-called decay index was proposed. Marbles are sensitive to weathering and have different volume changes under exposure depending on fabric parameters. The volume extension index of marble, based on thermal expansion measurements under dry and water-saturated conditions, is proposed as a decay index for quantifying sample stability and for defining the directions of maximum and minimal dilatation. Such decay index was implemented to different marble types and it was turned out that marbles with the larger decay indexes are more prone to weathering than with smaller ones. The effect of changing climate and, in consequence, different weathering actions can help to calculate or forecast risk numbers based on the Vp data in combination with the proposed decay index especially for marbles.
... The ultrasonic velocity of the P-wave (V p ) in transmission was measured using a Geotron Elektronik instrument with 350 kHz probes. V p was assumed as a reliable parameter to estimate the marble conservation state, as previous studies have shown the strong relation existing in marble between V p , porosity, compressive and tensile strength Ruedrich et al. 2013;Menningen et al. 2018). ...
In the present study, 5 different consolidants were tested on 5 different marble varieties preliminarily subjected to artificial weathering, to evaluate their consolidating effectiveness and thermal behavior after consolidation, in terms of residual strain after heating–cooling cycles in dry and wet condition and tendency to bowing. Treatments based on ethyl silicate, with and without a coupling agent to improve the performance on calcitic substrates, exhibited modest increases in cohesion after consolidation, as well as an increase in the thermal expansion coefficient and some residual strain at the end of the cycles. Paraloid B72 caused minor alterations in the pore system and limited increases in ultrasonic velocity, while the so-called “acrylic total impregnation” method led to an almost complete pore filling and significant improvements in cohesion. While the latter samples apparently resisted well to heating–cooling cycles, samples impregnated with Paraloid B72 exhibited progressive collapse of the fabric, likely due to the low glass transition temperature of Paraloid B72. Ammonium phosphate proved to be able to significantly improve marble cohesion and led to lower residual strain after heating–cooling cycles, compared to untreated marble. The DAP-treatment also exhibited a significant ability to slow down further bowing of already bowed slabs and to prevent bowing of initially planar slabs.
... In the last decades, plenty of NDTs have been conceived or applied to buildings and structures and they are continually improved. Some of them are: the parallel seismic method [2], the impulse response method [3], the impact-echo method [4], the ultrasonic tomography [5], the ground penetrating radar [6] and the impedance tomography [7]. Among these NDTs, a great interest is currently placed on damage qualification criteria based on Acoustic Emission (AE) monitoring [8], where it is worth mentioning the multitechnique approaches, which combine AE with dynamic identification and/or digital image correlation techniques [9-10-11]. ...
In this work, the Acoustic Emissions (AEs), detected in real-scale Reinforced Concrete (RC) beams which have been tested under four-point bending, are investigated and correlated with their structural responses and damage evolutions. Two different reinforcing bar arrangements, with or without shear stirrups, were designed in order to obtain bending or shear failure modes, respectively. Moreover, some of the beams were casted with the addition of steel fibers in the concrete mixture. A loading procedure characterized by several cycles of increasing amplitude up to failure was implemented. Beams failure behaviors and the aptitude of four AE-based indices to assess their damage level, are presented and compared. Moreover, some relevant variables possibly affecting the indices performance are analyzed. The steel fibers enhanced shear strength by restricting the development of inclined cracks in the beam without stirrups. Finally, it can be figured out that AE indices showed a quite good correlation with cracking initiation and progression. Therefore, they proved to be competent for both monitoring the RC beams loading response and detecting eventual local damages, even for fiber-reinforced concrete members.
... Ultrasonic velocities of marbles strongly depend on the moisture content of the rock. Marbles can show velocities of 3.0 km/s and less in the dry state; while velocities may reach about 6.0 km/s under water-saturated conditions (Rüdrich et al. 2001a;Weiss et al. 2002a;Siegesmund et al. 2009;Menningen et al. 2018b). The pore space developing in marbles is small but very efficient in reducing the velocities and also increasing them due to fluid saturation. ...
After almost 200 years of exposure, the monuments of General Scharnhorst and Bülow have been analysed by means of ultrasound. Both sculptures are made of Carrara marble, both sculptures have been exposed to the same environmental influences and both sculptures are, based on the results of the ultrasonic measurements, in alarming conditions. This statement can be made because of the data of three different measurement investigations within the last 12 years. In this short exposure time, the already low velocities have been reduced by 16.2% and 14.7%. The very low average velocity of 2.8 km/s for the sculpture of General Bülow and a slightly higher average velocity of 3.2 km/s for the Scharnhorst sculpture indicate that both sculptures are in a poor condition, even though a protective winter shelter has been used since 2004. Comparing tomographic velocity measurements performed in 2006 with the measurements made in 2018 was possible and showed that even areas with a thickness up to 90 cm show alarming low ultrasonic velocities down to 2.6 km/s. Even if the circumstances for both sculptures have been the same, they differ in their weathering state. The careful and transparent documentation of all measurements was in this context the most important aspect for the comparative studies. Irregularities in their weathering behaviour of the two statues can be distinguished, allowing an in-depth analysis of the deterioration of the marble.
... They are also facing the same thermodynamic destiny. Once exposed or excavated, they will deteriorate and eventually collapse completely due to the effects from physical, chemical, biological, and anthropogenic activities [5][6][7][8][9][10]. Many studies have been carried out on the protection of stone cultural relics, to understand the weathering mechanisms, to slow down the weathering process and extend their lifetime [11][12][13][14][15][16][17]. ...
Fossils are nonrenewable natural heritages formed by Mother Nature. After being excavated or exposed, fossils can be destroyed by weathering and water erosion. However, until now, there is very limited research work on fossil conservation. In this work, we focus on the protection of pterosaur fossils found in Hami, which are very sensitive to water. Four siloxane-based polymeric sols, including from tetraethyl orthosilicate and other three hybrid siloxane monomers, are prepared by controlled hydrolysis protocol. Their chemical and physical properties and performances as fossil protection materials are examined. Experimental data show that all sols have excellent permeabilities, decent reinforcement abilities, good resistance to light and heat aging. The organic moieties in the hybrids can also significantly increase the fossil’s hydrophobicity and reduce the cracking of the gels. The results indicate siloxane-based polymers can be very potential protection materials for fossils. And the hybrid polysiloxane sol containing epoxy function groups has overall the best performances.
Top left: severely degraded fossil due to water erosion, top right: structures of four sols Bottom: significantly improved fossil resistance to water after treated by silica sols, from left to right: treated by TEOS-TMPM-s, TEOS-TMPE-s, TEOS-BTME-s, TEOS-s and control sample.
... These are the homogeneity criterion, which is related to the textural and chromatic homogeneity of the potentially productive lithologic units, and the dimension criterion, referring to the thickness of the productive unit (Carvalho and Lisboa 2018). However, in some cases, like the marbles, the textural and colour heterogeneity enhances the visual quality of the material (Menningen et al. 2018a). Regardless of the rock type the fracturing plays an important role in the definition of the available areas (Santos et al. 2018), since in high fractured massifs is more difficult extracting commercial blocks. ...
... Moreover, the presence of swellable clay minerals as well intracrystalline swelling causes hydric expansion and is an important factor for the weathering behavior and deterioration (Pötzl et al. 2018a). Marbles usually shows a lattice and shape preferred orientation, consequently the thermal dilatation exhibits a strong directional dependence and irreversible length change after repeated heating cycles under dry and wet conditions (Menningen et al. 2018a). Sandstones can show expansion and shrinkage during imbibition of fluids depending on the surface tension of the imbibing fluid, the degree of saturation, the rigidity and the effective pore radius (Möller et al. 2018). ...
