Marble Blocks Research Articles

An industrial robot-based sawing method for natural stone sculpture

Abstract In order to enhance the efficiency of stone sculpture machining while reducing natural stone waste and environmental pollution, a method for the efficient and green sawing of natural stone sculptures using industrial robots is proposed. The model contour is used as the directrix of the ruled surface to construct a ruled surface model that minimizes volume. The contour curve corresponding to this minimized-volume ruled surface model serves as the machining path for an integrated robotic diamond wire cutting system. A ruled surface model of Stanford Bunny was obtained by sawing a marble block using the robotic diamond wire cutting system. The experimental results show that the material removal rate of the robotic diamond wire cutting is 1.37 times that of saw blade cutting and 2.30 times that of grinding. The volume of stone powder generated during the processing was 0.16×10⁷mm³, accounting for only 1.47% of the total stone powder produced during the grinding process. In summary, the proposed method not only enhances processing efficiency but also reduces natural stone waste and mitigates environmental pollution.

Programmable Chemical Reactions Enable Ultrastrong Soft Pneumatic Actuation.

Soft pneumatic actuation is widely used in wearable devices, soft robots, artificial muscles, and surgery machines. However, generating high-pressure gases in a soft, controllable, and portable way remains a substantial challenge. Here, a class of programmable chemical reactions that can be used to controllably generate gases with a maximum pressure output of nearly 6MPa is reported. It is proposed to realize the programmability of the chemical reaction process using thermoelectric material with programmable electric current and employing preprogrammed reversible chemical reactants. The programmable chemical reactions as soft pneumatic actuation can be operated independently as miniature gas sources (∼20-100g) or combined with arbitrary physical structures to make self-contained machines, capable of generating unprecedented pressures of nearly 6MPa or forces of about 18kN in a controllable, portable, and silent manner. Striking demonstrations of breaking a brick, a marble, and concrete blocks, raising a sightseeing car, and successful applications in artificial muscles and soft assistive wearables illustrate tremendous application prospects of soft pneumatic actuation via programmable chemical reactions. The study establishes a new paradigm toward ultrastrong soft pneumatic actuation.

Influence of blasting charge distribution on the energy required for communition of rock

The most energy-intensive process in the mining industry is particle size reduction - comminution. The first phase of this process is blasting to fragment the rock from the initial Boussinesq's half-space size. Scientific literature demonstrates that the output of a blast in terms of fragment size distribution can be manipulated by varying the specific charge (powder factor) and charge distribution. This study focuses on the influence of blasting on the internal resistance of the blasted fragments; in particular the influence of the spatial distribution of charges. Small-scale blasts were performed on 14 marble blocks using different powder factors and charge distributions. Three control blocks were fragmented by mechanical means for comparison. The results show the correlations between charge distributions and the specific energy of mechanical comminution. Opportunities for adjusting charge diameter and distribution in opencast blasts to improve the performancet of comminution circuits are discussed.

Assessing structural integrity of non-homogeneous systems by means of Acoustic Emissions and Non-Extensive Statistical Mechanics

Taking advantage of the interevent time intervals, namely the time intervals between two successive acoustic events recorded during mechanical loading of structural elements, it is attempted to detect indices warning about upcoming failure. The innovative aspect of the study is that the analysis is implemented in the frame of Non-Extensive Statistical Mechanics, a discipline founded on a class of entropies violating the additivity principle, which is the cornerstone of the Boltzmann-Gibbs Statistical Mechanics. The specimens used for the experiments were marble blocks simulating either fragmented and restored epistyles or mutually interconnected intact epistyles of the Parthenon Temple on the Acropolis of Athens. The specimens consisted of three mate­rials (marble, metallic connectors and cementitious pastes) exhibiting, thus, a strongly non-homogeneous nature. The entropic index, i.e., the parameter quantifying the degree of non-additivity, was used for the analysis of the ex­pe­rimental data. The results were considered in juxtaposition to the re­spective ones from experimental protocols with specimens of macroscopically homo­geneous nature. It was concluded that the temporal evolution of the entropic index provides very good insight into the level of damage ac­cumu­lated in the loaded structure, independently of whether the structure is homogeneous or not, providing an interesting pre-failure indicator.

Geomorphological assessment as basic complement of InSAR analysis for landslide processes understanding

Landslide research has benefited greatly from advances in remote sensing techniques. However, the recent increase in available data on land surface movement provided by InSAR techniques can lead to identifying only those areas that were active during data acquisition as hazardous, overlooking other potentially unsafe areas or neglecting landslide-specific geological settings in hazard assessments. Here, we present a case study that serves as a reminder for landslide researchers to carefully consider the geology and geomorphology of study areas where complex active movements are detected using InSAR technology. In an area extensively studied using InSAR and UAV-related techniques, we provide new insights by applying classical approaches. The area is the coastal stretch of La Herradura, and its importance lies in the fact that it has served as an illustrative example in the Product User Manual of the European Ground Motion Service, a platform that provides ground motion data on a European scale. Our approach is to revisit the area and carry out qualitative geological and geomorphological assessments supported by UAV surveys and GIS spatial analysis on a broader scale than previously published investigations. Our classical approach has yielded the following new observations, crucial for risk assessment and land management: active landslides identified by InSAR techniques since 2015 are bodies nested within large mass movements that affect entire slopes. A variety of processes contribute to slope dynamics, such as large slumps, marble rock spreading and block sliding, and surface rock falls and topples. The revised delineation of the landslide bodies reveals an area almost five times larger than previously mapped. These new findings in a well-known area highlight (1) the importance of updating and downscaling previous maps and (2) the ongoing importance of classical fieldwork and desk studies as basic complements to modern InSAR analyses.

Effect of Marble Dust Powder on the Properties of Fresh and Hard Concrete

The goal is to investigate the potential for employing byproducts from various industrial processes in the creation of ground-breaking mortar and concrete. The dust produced during the marble-cutting operation is put to good use. Different percentages of this garbage were recommended to be used in conjunction with or in place of cement in the making of concrete. The research looked into the possibility of using marble dust, which is produced during the shaping of marble blocks, as a cementitious material in concrete. In areas where they are readily available and can reduce construction costs, the study found that dust from marble slabs could be employed as a cementitious material in concrete mixtures. The discarded marble dust is mixed with cement in proportions of 5, 10, 15, and 20% of the standard concrete mix. Both the fresh and hardened characteristics of the produced combinations were investigated. Compressive and tensile strengths were measured after being cured for varying periods of time, both when marble dust was used as a partial replacement and when it was not.

Time-Lapse GPR Measurements to Monitor Resin Injection in Fractures of Marble Blocks.

The objective of this study is to test the feasibility of time-lapse GPR measurements for the quality control of repairing operations (i.e., injections) on marble blocks. For the experimental activities, we used one of the preferred repairing fillers (epoxy resin) and some blocks from one of the world's most famous marble production area (Carrara quarries in Italy). The selected blocks were paired in a laboratory by overlapping one over the other after inserting very thin spacers in order to simulate air-filled fractures. Fractures were investigated with a 3 GHz ground-penetrating radar (GPR) before and after the resin injections to measure the amplitude reduction expected when the resin substitutes the air. The results were compared with theoretical predictions based on the reflection coefficient predicted according to the thin bed theory. A field test was also performed on a naturally fractured marble block selected along the Carrara shore. Both laboratory and field tests validate the GPR as an effective tool for the quality control of resin injections, provided that measurements include proper calibration tests to control the amplitude instabilities and drift effects of the GPR equipment. The method is accurate enough to distinguish the unfilled fractures from the partially filled fractures and from the totally filled fractures. An automatic algorithm was developed and successfully tested for the rapid quantitative analysis of the time-lapse GPR profiles collected before and after the injections. The whole procedure is mature enough to be proposed to the marble industry to improve the effectiveness of repair interventions and to reduce the waste of natural stone reserves.

Discontinuity Detection System in Marble: Analysis of the Time-Frequency Characteristics of Ultrasonic P-waves

Abstract This study attempted to determine both the presence and the appearance of the surface of a crack artificially created in a marble block without axial loading or compression by FFT analysis of ultrasonic longitudinal sound waves by scanning the surface. In such respect, the study differs from other studies in the literature. The aim of the study was to minimize marble waste by determining the most appropriate slab cut direction based on the orientation of the fracture or discontinuity within the marble block. During location-controlled scanning of the marble surface, mean longitudinal wave velocity, Young modulus, Poisson ratio and longitudinal wave velocity variation data were obtained using a V-Meter Mark IV™ ultrasonic test device. For each location, longitudinal ultrasonic velocity data was taken at 250 kHz sampling rate and 256 data points were created. Data from the computer environment were subsequently reorganized using the MATLAB software and FFT conversions for such velocity data were obtained for each location. Then, the peaks of the FFT transformation components were determined by using the “Findpeaks” function in MATLAB‘s signal processing toolbox. The number of peaks in the 50-60 kHz range was determined for each location. A single difference was determined between the peak numbers at the locations within the cracked and uncracked regions. By examining the FFT graphs, it was determined that such additional peak occurring in the cracked regions appeared as a second frequency component near the dominant frequency values. Points with secondary frequency were recorded as 1, while all other points were recorded as 0 in a new matrix. Such data matrices created for each sample were examined by visualization in the form of surface graphics. Using these graphics, the orientations of discontinuities within the marble block may be determined according to the scanning surface.

Effect of metakaolin on the microstructure of cement-based artificial marble slabs incorporating natural marble offcuts under vacuum vibration compaction method

Large number of natural marble resources consumption and waste caused by the increasing demand and mining technology of natural marble have severe impact on the surrounding land and ecological environment, while cement-based artificial marble is a good place for these natural marble offcuts to go. The natural marble offcuts pretreated to different particle sizes in this study were mixed with white Portland cement coupled with a certain amount of acrylic emulsion and polypropylene fiber to fabricate cement-based artificial marble slabs (CAMS) via vacuum vibration compaction (VVC) moulding method. Among which metakaolin (MK) was incorporated to explore its effect on the properties and microstructure of CAMS. The results denoted that the properties of CAMS were susceptible to the contents of MK. At the optimal MK content of 4 wt%, the optimal flexural strength, bulk density and water absorption of the specimens at 28 d were 19.0 MPa, 2506 kg/m3 and 0.32 %, respectively. Meanwhile, results obtained by hydration heat, SEM, MIP and 29Si NMR tests show that the addition of MK reduced the total porosity of CAMS specimens and the degree of polymerization of silicon-oxygen tetrahedra in CSH gel, and effectively enhanced the toughness of the specimens. The evident reduction of early hydration heat with the incorporation of MK is of great significance to moulding and early curing process of large volume cement-based artificial marble blocks in actual production.

Modeling and electromechanical performance of improved smart aggregates using piezoelectric stacks

Smart aggregates (SAs) are often formed by embedding lead zirconate titanate (PZT) patches into concrete or marble blocks. They not only have the advantages of low cost, quick response, high reliability, and long service life, but also possess comprehensive actuating and sensing abilities, and have been widely used in structural health monitoring in the field of civil engineering. However, due to the plate-like geometry of the PZT patch and the limited number of layers, SAs have a relatively short sensing range. To solve this issue, a new type of SA using piezoelectric stacks was developed. Theoretical modeling of this new transducer was established, and prototypes were fabricated. Comparisons between the theoretical predictions and the experimental results are presented, and good agreement can be found. The effects of the key parameters, including the total height of the specimen, the elastic modulus of the cement, the radius of the piezoelectric stack, the thickness of the piezoelectric layer, and the number of piezoelectric layers in the piezoelectric stack, on the electromechanical properties were analyzed, and the guidelines for optimal design were presented. In addition, the improved and the traditional SAs were used to monitor the water content in soil specimens based on the electromechanical impedance technique. The results showed that the improved SAs using piezoelectric stacks are more sensitive than the traditional ones, and have good potential in structural health monitoring in the field of civil engineering.

Camblakov opis gradnje dečanskog hrama - njegove osobenosti i uzori

In describing the life and deeds of Serbian Holy King Stefan of Dečani (1322-1331), the author of the second biography of the Serbian king and abbot of the Dečani Monastery, Grigorije Camblak (c.1364-1419/1420) gives an account of the construction of the Holy King's endowment dedicated to Christ Pantokrator (Figs. 1-2). He describes in detail the way in which the marble blocks of the church were carved with great skill, prepared and perfectly inserted into the overall structure of the building. He states, "...and the stones are wonderfully and most artfully joined together, so that it seems as if the face of the whole church is one stone wonderfully joined together with skill, so that it seems as if one piece of stone, appearing in an unspeakable beauty…since it is a perfectly carved stone and testifies to the dignity of those who created it" (Camblak, 1936, p. 23; Trifunović, 1985, p. 183). The paper notes that the quoted description of the church construction emphatically represents learned ancient literary topos used to describe the most representative architectural monuments, especially those made of marble and deals with the origin and tradition of this specific way of describing the building construction.

2D/3D SOIL CONSUMPTION TRACKING IN A MARBLE QUARRY DISTRICT

Abstract. Complex extractive districts, such as the marble quarries in the Apuan Alps (northern Italy), require soil consumption monitoring over the years that could be achieved through high-resolution remotely sensed data. To derive 2D and 3D indicators with appropriate resolution for annual monitoring of high-resolution changes in soil consumption, aerial images, LiDAR acquisitions, satellite data, and Remotely Piloted Aircraft Systems (RPAS) acquisitions were used. In particular, open-access Sentinel-2 multispectral satellite imagery with a spatial resolution of 10 m was used to assess cover changes (2D), and then refined by manual interpretation for 5 years (2016-2021). 3D changes were detected by comparing free aerial LiDAR data from 2009 and 2017, integrated with two stereo models obtained from Pléiades high-resolution satellite images from 2020 and 2022. 3D changes observed over the years by algebraic elevation comparison, performed in QGIS 3.x environment, highlight quarries characterized by intense mining activities (extracted marble blocks, characterized by positive elevation differences) and quarry area management (debris disposal and service infrastructure construction, characterized by negative elevation differences). The combined use of 2D and 3D change indicators can be challenging in order to correctly represent soil consumption over the years. A dual 2D/3D webgis client have been developed for proper representation of 2D/3D spatial indicators of ongoing extraction activities in the Carrara marble basin: high-resolution images have been served as tiled data, while 2D/3D spatial indicators are served as static and/or tiled vector data. Open-Source libraries have used in data processing, serving and representation inside a map interface.

Industry-scalable wall tile composition based on circular economy

Within the framework of the circular economy and waste recovery, this work deals with the possibility of manufacturing wall tiles whose bodies include waste in their formulation. The wastes selected are crushed scraps of defective fired tiles, marble dust residues and fly ash from thermal power plants. Fired tile waste is a material of interest for reuse due to its similarity to the product to be developed. Marble dust, from the manufacture and mechanical handling of marble blocks, is useful as a source of calcium oxide to replace the calcium carbonate which generates porosity. Fly ash, from the combustion of coal in thermal power stations, is a vitreous material that has undergone a thermal process at high temperature and can therefore be integrated into ceramic body compositions.The obtained results show the correct formulation of sustainable porous bodies from these wastes in combination with clay in different proportions. In this way, it is possible to manufacture porous substrates for tiles using a percentage of waste higher than 50wt%, obtaining appropriate properties in the fired product: linear shrinkage, water absorption, mechanical strength and moisture adsorption.

Wooden remains found at Daskyleion and their anatomical examination

The wooden remains found in T6 and T7 tumuli and “Three-Room Building” complex of Acrodaskyleion are the subject of the study. These samples were found in the sockets of copper alloy arrowheads in T6 Tumulus. Also, another sample was found in a bullet covered tenon on a marble block in the T7 Tumulus. Anatomical examination on wooden samples, the arrows was made of poplar/willow. The wooden specimen found in the tenon belongs to the Black pine, the genera/species identified are the common trees in the region. Black pine is the main forest tree, which have a wide natural distribution area, and poplar/willow grow through the rivers in the region. As conclusion, the types of wood processed were selected according to its function. The tenon was made by black pine which is more resistant to external deteriorations. The wooden part of the arrows is made of low density and flexible poplar/willow wood.

Analytical Models and Laboratory Measurements to Explore the Potential of GPR for Quality Control of Marble Block Repair through Resin Injections

This work aims to analyze theoretically and with laboratory tests the sensitivity of high-frequency GPR (Ground-Penetrating Radar) to resin injections used in the building and ornamental stone industries to repair marble blocks before final slab cutting. We simulate uniform fractures in the laboratory using small regular marble blocks and we compare the results of GPR tests with the analytical model of the thin bed reflections. We performed two series of GPR surveys with a 3 GHz antenna, progressively increasing the fracture thickness from 0.25 mm to 16 mm, to analyze the results on two simulated conditions: open fracture and repaired fracture. The repaired condition was simulated by substituting the resin layer with polyvinyl chloride (PVC) sheets because the permittivity of PVC is quite similar to the permittivity of epoxy resin. According to the analytical models, when a thin air-filled fracture is filled with resin, the received signal amplitude is expected to decrease by 33% (26% if resin is simulated with PVC). The results showed a very good match between the predictions and the real data observations when the fracture is thicker than 4 mm. Although the analytical and laboratory results show some deviations when the fracture is thinner than 4 mm, the qualitative trend of the amplitude variations is still consistent with the predictions and the 3 GHz antenna can resolve the change in the filling material down to the minimum tested thickness (0.25 mm). As a result, our findings validate the GPR method as a proper tool for nondestructive quality control of resin injections in marble fractures.

Archaeological and archaeometric investigation of the Roman marble cargos of Porto Cervo (Arzachena, Sassari, Italy) and Secche della Meloria (Livorno, Italy)

AbstractMinero‐petrographic and geochemical analyses carried out on 35 samples of marble blocks belonging to shipwrecked cargos at Porto Cervo (Arzachena, Sassari, Italy) (23 samples) and Secche della Meloria (Livorno, Italy) (12 samples) indicated that the marble originated from the Apuan Alps (Italy), which implies that the ships presumably came from the Roman city of Luna. Ceramic finds enabled the dating of one shipwreck to the end of the second/beginning of the third centuries ce and the other one to the first–second centuries ce. After an archaeological discussion, authors propose that the destination of the important Porto Cervo cargo (around 222 tonnes) could have been Africa or Sicily, while a site on the way to Portus (Rome) is suggested as a possible destination for the smaller (84 tonnes) Secche della Meloria shipment.

THE SURVEY OF THE MONUMENTAL FOUNTAIN IN THE TOWN OF DALMINE: A PRELIMINARY WORK FOR THE CONSERVATION PROJECT

Abstract. The Monumental Fountain of Dalmine was built to celebrate the 20th anniversary of Benito Mussolini’s historical address held on March 20, 1919, to which the square was dedicated. In the basin stood a large marble block on which some sentences of the Duce’s speech were carved. The work was partially destroyed at the end of the World War II and the block was removed. Today, what remains of the Dalmine Fountain constitutes the privileged meeting place of the city. However, it has great sealing problems as well as high management and maintenance costs, which prevent its normal functioning. Consequently, it is kept empty for many months of the year and filled with water only in the summer. This essay intends to propose a study based on the analysis of historical sources and 3D survey and modelling techniques aimed to understand the historical and urban value of the monument, to support its conservation and to enhance its role as a central meeting point for the town.

Comparative study on the performance of sand-based mortars from marble, floor tile and cinder block waste

This paper presents a comparative study of the role played by sands extracted from marble, floor tile and cinder block wastage on the properties, mechanical performance and durability aspects of a siliceous sand-based mortar. The main purpose is to appreciate the recovery of these sands in the composition of the mortar and to look for the best substitute for natural sand. Three series of mortar mixes were manufactured and compared to the formulation of the control mortar, which was based on a constant quantity of cement and a constant ratio of water/cement equal to 0.56. The various waste sands were used to substitute the dune sand in the reference mortar, at rates of 5%, 10%, 15% and 20%. Several tests were carried out on mortar specimens, namely: density, consistency, air content, mechanical strength tests, water absorption tests, and resistance tests against acid attacks. The results obtained, show a favourable effect of all sands on the properties in the fresh, hardened states and on the durability of the mortars. The mortar at 20% of marble sand waste is the one with the best performance of all the mortars, in terms of consistency, air content, flexural strength, water absorption and resistance to attack by acetic acid solution. However, the mortar with 20% of floor tile sand exhibits the highest compressive strength. Furthermore, the mortar-based 15% of cinder block sand is more resistant to attack by sulphuric acid. Thus, the use of ‘waste’ sand with appropriate dosages lowers the consumption of natural aggregates and contributes to improving the environment by reducing original waste.

Paleogeographic position of the central Dodecanese Islands, southeastern Greece: The push-pull of Pelagonia

Abstract The paleogeographic position of the central Dodecanese Islands at the transition between the Aegean and Anatolian plates plays a considerable role in understanding the link between both geologically unique domains. In this study, we investigate the tectonic history of the central Dodecanese Islands and the general correlation with the Aegean and western Anatolian and focus on the poorly studied islands of Kalymnos and Telendos. Three different major tectonic units were mapped on both islands from bottom to top: (1) The Kefala Unit consists of late Paleozoic, fossil-rich limestones, which have been deformed into a SE-vergent fold-and-thrust belt sealed by an up to 200-m-thick wildflysch-type olistostrome with marble and ultramafic blocks on a scale of tens of meters. (2) The Marina Basement Unit consists of a Variscan amphibolite facies basement with garnet mica schists, quartzites, and amphibolites. (3) Verrucano-type formation violet shales and Mesozoic unmetamorphosed limestones form the Marina Cover Unit. Correlation of these units with other units in the Aegean suggests that Kalymnos is paleogeographically located at the southern margin of the Pelagonian domain, and therefore it was in a structurally upper tectonic position during the Paleogene Alpine orogeny. New white mica 40Ar/39Ar ages confirm the Carboniferous deformation of the Marina Basement Unit followed by a weak Triassic thermal event. Single-grain white mica 40Ar/39Ar ages from pressure solution cleavage of the newly defined Telendos Thrust suggest that the Marina Basement Unit was thrusted toward the north on top of the Kefala Unit in the Paleocene. Located at a tectonically upper position, the units exposed in the central Dodecanese escaped subduction and the syn-orogenic, high-pressure metamorphism. However, these units were affected by post-orogenic extension, and the contact between the Marina Basement Unit and the non-metamorphic Marina Cover Unit has been reactivated by the cataclastic top-to-SSW, low-angle Kalymnos Detachment. Zircon (U-Th)/He ages from the Kefala and Marina Basement Units are ca. 30 Ma, which indicates that exhumation and cooling below the Kalymnos Detachment started in the Oligocene. Conjugate brittle high-angle normal fault systems, which resulted in the formation of four major WNW-ESE–trending graben systems on Kalymnos, localized mainly in the Marina Cover Unit and probably rooted in the mechanically linked Kalymnos Detachment. Since Oligo-Miocene deformation in the northern Dodecanese records top-to-NNE extension and the Kalymnos Detachment accommodated top-to-SSW extension, we suggest that back-arc extension in the whole Aegean realm and transition to the Anatolian plate is bivergent.

Honorary Decrees from Ephesos for Winning Athletes in Panhellenic Games

A marble block from Ephesos bears the text of three honorary decrees dating back to 300 B.C. ca. According to the inscriptions, the city council granted citizenship and prize money to young athletes who distinguished themselves in prestigious panhellenic games. The main figure in the second inscription, Athenodoros, ἰσοτελής in Ephesos before being granted citizenship, is mentioned in I.Ephesos 2005. On the occasion of this decree, his talent earned him a subvention from the city; a similar grant might have been assigned to another rising athlete, Timonax, referred to in the third inscription.