Effectiveness, compatibility and durability of consolidants for marble: a review of the last ten year of researches

The choice of suitable consolidant treatment for cultural stones is one of the main challenging issue for conservation and protection of ancient masonry. Among building materials, marble is one of the most used for building and sculptures. Due to its low porosity, the assessment of suitable treatment for marble consolidation is not trivial; beside, the type of product, treatment methodology, effectiveness and compatibility investigation and durability monitoring have to be taken in great account. Recently, researchers have extensively tested and proposed new products for consolidating carbonate stones, including organic and inorganic products, nanoparticles, biological organisms (De Muynck et al., 2010). Nevertheless, no entirely satisfactory treatment is currently available for marble consolidation. At the same time, no unique evaluation criteria to use as laboratory estimators of consolidating performances have been assessed . The present paper aims to carry out a review of the state of art, based on the last ten years of researches, on consolidants for marble substrate. We summarize the different type of commercial and research products proposed for marble consolidation, by comparing also effectiveness, compatibility and durability of each proposed product, in function of consolidant features (i.e., product concentration, solvent type) and treatment methodology (application process, and contact time)

Evaluation of the technological features of late roman cooking ware classes from Akrai (Syracuse, Sicily)

In this work, a provenance and technological investigation on cooking-ware potteries from the ancient Greek -Roman town of Akrai (Palazzolo Acreide, Syracuse, Sicily) has proposed. A multi-methodological approach have been used to study the manufacture quality of analysed materials; in detail, petrograp hic, mineralogical, spectroscopic, chemical, porosimetric and micro-morphological analyses have been applied. The study providesfundamental contribute in archeological issues related to circulation in Sicily of cooking -ware productions during Late Roman Age; in fact, the obtained results allow to recognize in the site the presence of different well-known cooking-ware Roman productions, highlighting interesting questions about the technological and manufacture properties of this class of materials

Visualization and quantification of weathering effects and water uptake processes in natural building stones by using neutron imaging

Calcarenites are the most widely used natural building stones in Sicily. They are frequently subjected to very intense degradation due to salt growth [1, 2]. This process is often responsible for strong modifications of their pore network [3] and has a great influence in the mechanical properties and the durability of materials [4]. In addition, as water transport has a key role in the degradation processes, the quantification and visualization of fluidflow into the pore network of degraded stones represent useful tools in understanding the weathering process. Classical approaches are usually performed by applying laboratory test routines for the determination of water absorption parameters. However, they cannot provide a description of the local distribution of water inside the stone. In this framework, neutron imaging has been demonstrated as a powerful technique for the visualization and quantification of the water distribution in partially saturated porous media [5]. Moreover, the possibility to perform dynamic measurements allowed monitoring the water uptake as function of time and to explore the complex processes involved in fluid transport [6-8]. In this study neutron radiography has been used with the aim of: a) monitoring and visualizing the fluidflow patterns inside porous structure of a local calcarenite widely used as building and replace stone in several Cultural Heritages, namely Sabucina Stone; b) quantifying the water distribution as function of time, in order to understand the effects of weathering on the behavior of the stone against water. In detail, samples of un-weathered and artificially weathered[9] Sabucina Stone have been scanned with neutron imaging technique at the IMAGINE beam line located at the Laboratoire Léon Brillouin (CEA/CNRS) in Saclay (France). Capillary water uptake has been monitored over time in samples subjected to different salt crystallization cycles. Beside the qualitative data acquired from the raw neutron images (Figure 1(a)), quantitative results have been obtained thanks to the image processing of the radiographs (Figure 1(b)) [10]. First of all, the evolution of the wetting front position over time has been observed and the penetration coefficient has been determined. The results demonstrated that changes in the hydric properties of the stone occurred with the intensification of the degradation process. Even if a good agreement with standard capillary absorption test has been obtained [11], the non-perfect linearity of capillary uptake process has been evaluated, due to the evidence of preferential flow paths. Therefore, neutron images have been processed in order to obtain quantitative water distributions as function of time. The contour plot of the water content value highlighted that degraded stones absorbed greater volumes of water than the un-weathered ones, due to the strong modification of their pore structure. Moreover, in weathered samples the quicker and deeper vertical spreading of the water was associated with an intense horizontal migration through pores enlarged by the degradation mechanisms. Finally, side effects, probably due to the more intense action of the degradation process close to the sample surface, were evidenced, determining different capillarity absorption properties for the inner and surface regions. In conclusion, neutron radiography has allowed a better understanding of the deterioration mechanisms affecting physical properties of building stones, supplying relevant data for planning powerfully actions to improve their durability. References: [1] M. Steiger, S. Asmussen. Geochimica et Cosmochimica Acta2008; 72: 4291. [2] G.W. Scherer. Cement and Concrete Research1999; 29:1347. [3]S. Raneri, V. Cnudde, T. De Kock, H. Derluyn, G. Barone, P. Mazzoleni. Europen Journal of Mineralogy2015; 27: 279 [4] S. Yu, C.T. Oguchi. Engineering Geology2010; 115: 226. [5] E. Perfect, C.L.Cheng, M. Kanga, M.Z. Bilheux, J.M. Lamanna, M.J. Gragg, D.M. Wright. Earth-Science Reviews2014; 129:120. [6] G. Barone G, V. Crupi, F. Longo, D. Majolino, P. Mazzoleni, S. Raneri, J. Teixeira, V. Venuti. Journal Instrumentation2014; 9: C05024. [7] V. Cnudde, M. Dierick, J. Vlassenbroeck, B. Masschaele, E. Lehmann, P. Jacob, L. Van Hoorebeke. Nucl.Instrum. Methods Phys. Res. B 2008; 266:155. [8] M. Dierick, J. Vlassenbroeck, B. Masschaele, V. Cnudde, L. van Hoorebeke, A. Hillenbach. Nucl.Instrum.Methods Phys. Res. A2005; 542:296. [9] UNI EN 12370, Natural stones test methods: Determination of resistance to salt crystallisation, UNI ed., Milano, 2001. [10] F.H. Kim, D. Penumadu, D.S. Hussey. J. Geotech. Geoenviron. Eng.2012; 138:147.G. [11] G. Barone, P. Mazzoleni, G. Pappalardo, S. Raneri. Construction and Building Materials2015; 95:355

Archaeometric study of mortars from the Pisa's Cathedral Square (Italy)

The present work is focused on the study of forty-two mortars used in the construction of both Roman buildings, old Pisa’s Cathedral and Modern structures in the Miracles Square (Italy). This area, included since 1987 in the World Heritage List of the UNESCO, is famous for the presence of an important historical complex built in the Middle Ages (the Cathedral, the Baptistery, the Leaning Tower and the Monumental Cemetery). The archaeologists discovered some structures related to more ancient periods: the Roman domus (1st–5th centuries) and the older cathedral with its foundations and crypt (10th century). Based on OM, XRF, XRPD, TG-DSC and SEM-EDS analyses, the main characteristics of binder and aggregate of the mortars have been determined, and some raw materials used for the production of the analysed binding materials have been identified

Petro-archaeometric characterization of potteries from a kiln in Adrano, Sicily

Background: This work is part of a wide scientific project finalized to characterize the Sicilian pottery productions from Greek to Roman Age. In this prospective, local reference groups have been analysed in order to create a database of the circulation and production centres in Sicily during this period. In this framework, a set of 28 waste pottery fragments (III-II century B.C.) from a pit found during excavations at the fortification of Adrano (Sicily) have been studied. Characterization of the samples has been obtained by macroscopic, petrographic (OM), mineralogical (XRD) and chemical (XRF) analyses. Results: Macroscopic analysis of the studied potteries has allowed to distinguish four groups on the basis of grain size, porosity and clay paste color. Petrographic and mineralogical analysis, carried out on a selection of representative samples have allowed us to obtain useful information on the production technology of the studied samples. Moreover, information about raw materials and provenance of clay sediments has been obtained by comparing chemical data of the analysed samples with locally outcropping clay sediments reference data. Finally, chemical results on Adrano potteries have been compared with kiln wastes from Siracusa and Gela. Conclusions: The aim of the present work is to obtain fabric characterizations and technological information on a local reference group of ceramic specimens manufactured in Adrano (Sicily). Petrographic and mineralogical results allow us to esteem high firing temperature suggesting a good technological level of local production; in addition, chemical data suggest a local provenance of raw materials used in the production of the studied samples. The comparison with local production from Siracusa and Gela highlights several differences in the use of raw material and in the technological levels achieved in the different sites, over time. Therefore, this work provides a valuable contribution in defining the local scenario of ceramic production in South-Eastern Sicily during the Hellenistic Age and in producing local reference groups in the petro-archaeometric studies of archaeological potteries

3D Graphic for promoting Cultural Heritages: the example of Petraro archaeological site in Villasmundo (Melilli-Siracusa, Sicily)

This work is part of a wider project aimed to studying and promoting the archeological area of “Petraro” in Villasmundo (Melilli – SR), in collaboration with LegambienteMelilli – Sezione TimpaDdieri. Explored for the first time in 1967 by the archeologist Giuseppe Voza[1], the site exhibits the remains of an interesting prehistoric fortified village dated at XVI – XV sec. B. C.; this structure has been evaluated as an unicum in Sicily for its architectonical characteristics and archeological records[2].Unfortunately, for many years, the area has been abandoned and made inaccessible to visitors, causing an important degrade of the site. In the last decade, the use of virtual reconstruction of Cultural Heritage has become a recurring custom for visualization of several features of an archaeological site[3, 4]. In particular, 3D computer graphics have been interpreted as a useful tool for the understanding of prehistoric remains[5], often characterized by bad preservation and absence of documentary sources. For aforementioned, the aim of this paper is to present the results of a virtual model of the prehistoric village of Petraro and the archeological records recovered in the site. In this context, 3D modeling could clarify some features of the area and offer a new tool for promoting this archeological site

Pottery production during "romanization" of Sicily: an archaeometric study of plain table-ware classes from ancient Akrai (Sicily)

In this paper, petrographic, mineralogical and chemical analyses have been performed on plain table-ware fragments discovered in the ancient town of Akrai (modern Palazzolo Acreide, Syracuse, Sicily) and dated between the Hellenistic and the Late Roman periods (4th-5th/6thcentury A.D.). The project is developed in the context of the archeological debate on the cultural and political process occurred in Sicily since the 3rd century B.C. and known in archaeological literature as Romanization. In this framework, a gradually substitution of Greek-Hellenistic materials with the Roman ones has occurred in Sicilian colonies and the city of Akrai was deepened involved in this process. As the sensitiveness of material culture to cultural and social changes, the archaeometric investigation has been focused on provenance and technological manufacture aspects of table-ware production, in order to delineate the eventually changes took place in the area during the investigated period. The comparison of obtained data with numerous references local groups of ceramics allows to identify different highly specialized local productions, drawing-back the commercial movements of potteries in Sicily during Roman Age

Archaeometric study of mortars from the Pisa’s Cathedral Square (Italy)

The present work is focused on the study of forty-two mortars used in the construction of both Roman buildings, old Pisa’s Cathedral and Modern structures in the Miracles Square (Italy). This area, included since 1987 in the World Heritage List of the UNESCO, is famous for the presence of an important historical complex built in the Middle Ages (the Cathedral, the Baptistery, the Leaning Tower and the Monumental Cemetery). The archaeologists discovered some structures related to more ancient periods: the Roman domus (1st – 5th centuries) and the older cathedral with its foundations and crypt (10th century). Based on OM, XRF, XRPD, TG-DSC and SEM-EDS analyses, the main characteristics of binder and aggregate of the mortars have been determined, and some raw materials used for the production of the analysed binding materials have been identified

Mineralogical, petrographic and physical-mechanical study of Roman construction materials from the Maritime Theatre of Hadrian's Villa (Rome, Italy)

This paper presents the study of various Roman materials used in the construction of the Maritime Theatre, one of the main buildings in the Hadrian’s Villa complex, a designated UNESCO World Heritage Site located in Tivoli (Rome, Italy), dating to the first half of the II century A.D. The plaster layers (arriccio and intonachino) and overlying original Roman paintings that form the concave wall of the portico as well as some bedding mortars of the pyramidal stone elements (i.e. cubilia) of the circular masonry have been studied in particular. In addition, the acid volcanic rocks of the cubilia have been investigated, aiming to understand their state of alteration and geological origin. By mineralogical-petrographic microscopy (OM), diffractometry (XRPD), Raman spectroscopy, Point Load Tests (PLT), helium pycnometry, and particle size analysis, the composition and granulometric distribution of the aggregate, type and characteristics of the binder, and various physical-mechanical properties (density, porosity, water absorption, imbibition and saturation indices, mechanical resistance) of mortars and stones were defined. In addition, through digital image analysis of thin sections, the binder/aggregate ratio and some geometric characteristics of the aggregates (e.g. circularity) were determined. The research aims to improve the knowledge of the constructive technologies of the Maritime Theatre through the analysis of its materials