1,720,973 research outputs found
Studio mineralogico-petrografico finalizzato all'intervento di restauro conservativo del Mangia.
No full textReconstructing the history of the Portal of the Sala del Consiglio Generale of the Republic of Siena (Italy) using microstratigraphic analysis
No full textI materiali lapidei dell'architettura senese: l'arenaria pliocenica ("tufo impietrito"). Il supporto scientifico all'intervento di restauro di Palazzo Spannocchi
No full textLa competenza dell'esperto scientifico. Lo studio delle "patine" in sezione ultrasottile
No full textThe calcare cavernoso of the Montagnola Senese (Siena, Italy): mineralogical-petrographic and petrogenetic features
No full textAs a part of a broader research programme on the stones used in the historical buildings of the Siena area, we performed a mineralogical-petrographic study of the Calcare Cavernoso outcropping in the Montagnola Senese. It is a dolomitic limestone genetically related to the epidiagenetic evolution of the Triassic evaporitic-dolomitic succession known as Burano Anhydrite Formation. Various investigations (using polarizing microscope, X-ray diffractometry, SEM/EDS, cathodoluminescence, WDS electron microprobe) were carried out on the Calcare Cavernoso and its parent-rock, aimed to the characterization of the material. Our observations have allowed us to propose an outline of the petrogenetic evolution of the rock. Calcare Cavernoso appears to be the result of a massive process of dedolomitization occurring at the expenses of the dolomitic facies of the original Triassic evaporitic-dolomitic succession, following its re-exhumation at the end of the Apennine orogenesis. The intense tectonic fracturation of the dolomite favoured the circulation of meteoric waters in continental phreatic environment, with the consequent dissolution of sulphates and dolomite and the neoprecipitation of calcite. A late, pervasive vadose circulation, easily occurring in the already very porous rock, led to the development of karstic phenomena on various scales; increasing the porosity of the rock, they gave it the characteristic vacuolar appearance observed today
I materiali litoidi nell'architettura senese: tipologia, distribuzione e stato di conservazione.
No full textThe colour of the façades in Siena's historical centre: I. Glazings (calcium oxalate films s.s.) and other finishes on the stone materials of the Cathedral's main façade
No full textThis paper focuses on the long-debated topic of the so-called calcium oxalate films: their origin and meaning but also their age and original appearance. The restoration of the main facade of the Siena Cathedral provided a unique opportunity to this end, thanks to the possibility of an extensive and detailed sampling and (as rarely happens) a sufficiently accurate historical knowledge of the construction vicissitudes. This work, mainly based on a polarising microscopy study (coupled with X-ray diffraction and SEM-EDS analyses) of over a thousand thin and ultra-thin sections of 400 microsamples, demonstrates that the current relicts of films are the result of alteration and decay of ancient treatments. In most cases, these were linseed oil-based glazings (the use of this substance is confirmed by historical documents) and pigments. Their role was essentially aesthetic; their use dates the beginning of the fourteenth century and continued at least until the eighteenth century. © 2009 Springer-Verlag
Laser cleaning in the conservation of lapidary objects
No full textLaser cleaning is a novel technique in conservation procedures that has been recently employed in operative tests for the removal of alteration layers from the surface of stone artefacts, such as statues, architectural elements and decoration of various monuments and façades. This technique shows several potential benefits, such as fine, controlled and selective cleaning operations, that permit the effective removal of also chemically complex alteration layers and preserve the original patina on the stone surface. Here we discuss the mechanism of laser-induced cleaning of encrusted stones and we present a study regarding laser cleaning methods and analyses on various types of stone such as marble, limestone and sandstone from the Cappella di Piazza del Campo and Palazzo Pubblico in Siena, Italy. A laser system dedicated to this purpose has been developed and tested in practical cleaning tests
The Montagnola Senese marbles (Siena, Italy). Study of the microfabric and physical decay processes.
No full textThe aim of this study was to characterize the Montagnola Senese marbles (Siena, Italy), widely used in historical Sienese monuments, and to define the relationships between the marble’s microfabric and physical decay processes. A mineralogical-petrographic analysis of the most common varieties was conducted by light microscopy, computerized image analysis, cathodoluminescence, XRD and X-ray textural goniometry. Heating and cooling cycles were applied to different lithotypes to evaluate the role of the microfabric in physical decay induced by thermal stress. Water absorption trials were conducted on unaltered and aged samples to test the physical features and to evaluate the effects of artificial ageing. Finally, we studied the decay behaviour of these marbles in monuments in the historical centre of Siena. The results indicate markedly different water absorption properties of the various marble varieties and differences in their decay behaviour, both in the laboratory and in the monuments. This is mainly related to the microstructural features of the marbles, especially the grain size and grain boundary corrugation
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