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Geochemical and petrophysical characterization of volcanic raw materials with pozzolanic activity used in Roman ancient mortars: some case study
No full textVolcanic rocks are commonly used as aggregate or pozzolan in ancient mortars. Generally natural pozzolans are pyroclastic rocks with rhyolitic composition and high amount of glass. In ancient Greece the mortars were prepared using the volcanic tuff from Santorini island. In Roman times the mortars of several monuments were prepared with pozzolans from Pozzuoli (near to Vesuvius
volcano), as the famous Pantheon and Collesium in Rome. The artificial pozzolans represented by ceramic products (cocciopesto), as bricks, pottery and tiles. The Romans used both kinds of pozzolans to give hydraulic characteristics to the mortars, conglomerates and concretes exposed to the presence of moisture or water (e.g., foundations, rudus of floors, trullisatio-plasters, cisterns, wells, aqueducts, thermal baths). This work shows a comparison of geochemical, petrographic and physical characterization by OM,
SEM-EDS, XRF, XRD, TGA-DSC analysis, He-porosimetry and PLT test of pozzolanic volcanics used in the mortars of some ancient Italian Roman building
The ancient pozzolanic mortars and concretes of Heliocaminus baths in Hadrian's Villa (Tivoli, Italy)
Full text linkAim of this work is physical and mineralogical-petrographic characterization of the mortars from the Baths with
Heliocaminus, a special and unique architectural building in the complex of the Hadrian’s Villa in Tivoli. 30 samples
were investigated for composition and physical properties (density, porosity, water absorption, mechanical strength,
particle-size distribution of aggregate, etc.), representative of eight mortar groups: cubilia mortar, brick bedding mortars,
floor-coating and wall-coating bedding mortars, floor (rudus) and wall conglomerates (trullisatio), vault concretes, lime
plasters (arriccio).
Physical parameters, together the microscopic analysis and binder/aggregate ratio determined in three ways using image
analysis (on thin sections and on specimens) and weight-data from dissolution of binder, have shown interesting
relationship between the physical-compositional characteristics and the function of mortars within the structure of the
Heliocaminus baths.
To identify the minerals and the reactant phases between binder and aggregate, as well as the hydraulic degree, selected
samples were analysed with X-Ray powder diffraction (XRPD), thermogravimetry (TGA) and differential scanning
calorimetry (DSC) techniques. The obtained results provide a close relation between pozzolanic characteristics and
physical-mechanical properties of the mortars (i.e., punching strength index)
The ancient pozzolanic mortars and raw materials of the Heliocaminus baths in Hadrian's Villa (Italy)
No full textIn this work were studied ancient mortars and materials used to construct the personal baths of Emperor Hadrian, located in its Villa of Tivoli (province of Rome), a luxurious residence from the Roman Imperial Age (II century AD; Mac Donald and Pinto 2006). These baths is one of the most innovative and interesting building inside the Villa for the presence of the Heliocaminus room characterized by a dome-shaped coverage, various technical solutions and precious marbles (Columbu et al., 2014). The construction of these original baths is probably due to the Hadrian interest about architecture and for the dome structures.
Overall approximately 85 samples (including the stones) are taken from the baths, of which about 40 mortar samples divided in different groups according to their function, i.e.: bedding mortars of bricks and cubilia ashlars (opus reticulatum), mortars of marble coatings of the floors and walls, cocciopesto conglomerates (opus signinum) of floors (rudus) and walls (trullisatio), concretes of vaults (opus caemeticium), plasters of interior walls, volcanic rocks and lateritious fragments used as aggregate in the mortars, pyroclastites of cubilia ashlars and outcrops.
To determine the compositional characteristics the samples were analyzed by polarized microscope, microprobe (SEM-EDS) and X-ray diffraction (XRD, XRPD). The minero-petrographic characterization has allowed to define the geological provenance of materials used as aggregate in the mortars (e.g., volcanic scoria, leucitite, etc.) or for cubilia of the walls. The study of binder / aggregate ratio, obtained with two different analytical methods (with image analysis on thin sections and on specimen faces of mortar bulk sample; Columbu et al., 2015), has shown a discrepancy in some groups between the method of mixing dictated by Vitruvius and those used in the analyzed materials.
Through the thermo-differential analysis (TGA, DSC) the hydraulic degree of the mortars has been studied and compared with data of the physical properties (resistance index to puncturing, porosity, real and bulk density, etc.) in order to define the relationship between pozzolanic characteristics and mechanical strength. The results, together with the analysis of the aggregate particle size and morphology, have shown a clear relationship between the physical characteristics of the mortars and their function within the structure of the baths, explaining the choice and selection of raw materials.
This research have provided significant data about the preparation of Roman mortars and also on the different construction phases of the baths linked often, as well as for the Villa, to the stops due to the travels of the Emperor along the Empire boundaries
Petrographic, geochemical and physical characterization of volcanic rocks from the fortification of Bosa Castle (western Sardinia, Italy)
Full text linkThe fortification of Bosa Castle overlooking the valley of the river Temo and the medieval old town of Bosa (XII-XIV centuries). His tactical position militarily, which allowed control of the land from the sea to the river, setting up urban in the valley (Bosa Vetus), allowed the exploitation for centuries, even as a place of sighting to face sudden attacks of brigands or Saracen enemies. The site initially belonged to the Giudicato di Torres (around the X cent.), And finally twelve hundred to Malaspina (from Lunigiana). Later the castle suffered many renovations of Turrritani, Malaspina, Arborea, the Aragonese, although overall preserves the defensive structure built by the Marquis of Tuscany and Liguria. Its decline began in the second half of the sixteenth century in favor of nearby Alghero populated by Catalans. This research proposal intends to define the petrographical and physical features and the weathering alteration of geomaterial used for the castle. The study of petro-volcanological features (i.e. structure, sialic and mafic minerals, welding degree) by macroscopic observations is the starting point for preliminary recognition of the different stones. Then, the analysis of texture and paragenesis on thin section by optical observations are made. Laboratory tests have been conducted to evaluate the physical-mechanical properties (density, water-absorption, porosity, PLT punching index, compressive and traction strength). The mapping of alteration forms and the causes of decay, in relation to varying volcanites and microclimatic-environmental conditions, have been studied
K/Na-silicate, ethyl-silicate and silane nano-molecular treatments in the restoration of high porous limestone
Full text linkCarbonate sedimentary rocks (i.e., limestones) have been frequently used in historical times due to
easy availability and workability. These latter depend primarily by petrophysical characteristics
(porosity, bulk density) that influence the mechanical strength. However, the limestones with high
porosity (>30%) and a poorly cemented carbonate-matrix show chemical alteration (i.e., dissolution)
and physical decay (e.g., decohesion).
In this work it was taken as case study a biomicritic limestone belonging to the carbonatic miocenic
series (lower Tortonian) of Cagliari (southern-Sardinia, Italy). This limestone has a low-medium
cementing matrix containing hygroscopic clay and sea-salt phases, which make the rock degradable.
To limit the decay it can intervene with consolidating products (K-Na-silicate, ethyl-silicate) and
protective-chemicals (silane nano-molecular gel-coat) to reduce the porosity and permeability to the
liquid aqueous phase. Results highlight an increase of strength after consolidation and a decrease of
gas-permeability after protection-treatment, maintaining in both cases a good permeability to the
vapor-phase
Contribution of petrophysical analysis and 3D digital survey in the archaeometric investigations of the Emperor Hadrian’s Baths (Tivoli, Italy)
No full textThis work studies the Heliocaminus Baths. From an architectural point of view, this is a special and unique building in the complex of the Hadrian’s Villa in Tivoli. This research is carried out with a multidisciplinary approach combining petrophysical, petrographic and mineralogical characterization with the techniques of digital survey. The purpose of the research is to contribute to the understanding of Roman construction through the study of materials and from architectural aspects. Using mineral-petrographic and physical analysis, a set of samples (mortars and stones) was investigated for composition and physical properties (density, porosity, water absorption, mechanical strength, etc.). In the case of mortars, these parameters, together with the particle size distribution and the binder/aggregate ratio determined in two ways using image analysis (on thin sections and on specimens), have shown a relationship between the physical and compositional characteristics and the function of mortars within the structure of the Heliocaminus Baths. However, in some cases, different characteristics were detected between the mortars belonging to the same masonry and with same function in the building, showing a slight inhomogeneity in the production of mortars. Furthermore, some relationships between compositional, physical aspects (i.e. porosity, sorting and size of aggregate) and mechanical strength have been found. All the gathered data, linked to the point cloud 3D model, allowed an accurate location of the traces from the construction story of this structure
The Tharros archaeological settlement (Italy): A step back in time and a look to the future
No full textArchaeometric study of the Roman marbles reused in the late Antiquity St. Saturnino Basilica (Cagliari, Italy)
No full textThe St. Saturnino Basilica (Cagliari, Sardinia, Italy) rises over a sacred site since the origins of the town of Cagliari.
The original sepulchral function of the area were consolidated and implemented during the Roman Empire and it
became a Christian cemetery after the martyrium of St. Saturnino (beginning of the IV Century A.D.). In this period the
original chapel of the church was built starting a long evolution of the building across half a millennium, until its
Romanesque evolution. The basilica was abandoned and partially destroyed at the beginning of the XIV Century. The
formal technical reading of its architectural structure and elements is complicated by the frequent reuse of Roman
artifacts during the Byzantine and Romanesque phases as well as the presence of diachronic source materials. The
naked-eye analysis of geomaterials present in the monumental highlights a significant number of lithologies (i.e.,
various kinds of limestones and sandstones, marbles, volcanic rocks, etc.), some of which are in an advanced state of
alteration. We present the results of a multi-method archaeometric study (mineralogical-petrographic observations on
thin sections, XRF trace elements analysis and 18O vs. 13C stable isotope ratio investigation) concerning the architectural
stone elements reused in the basilica between the late Antiquity and Romanesque periods. The majority of lithologies
belongs to the local outcrops of Cagliari Miocenic geological formation (e.g., limestone and sanstones). The provenance
study has focused on classical marbles used for manufacturing Roman architectural elements (column shafts, bases,
capitals, pilasters, slabs, etc.), which are thought to come from extra-regional sources. All the different macrofacies of
marbles were sampled taking precise reference to the various construction phases and structural changes of the
monument occurred in the centuries. The preliminary results show that the marbles come mainly from Apuan Alps
(Italy) and subordinately from Greek quarrying areas
Characterization of the ancient mortars and 3D laser scanner survey to define the construction phases of the Heliocaminus Baths in the Hadrian's Villa (Tivoli, Italy)
No full textInside the Hadrian’s Villa in Tivoli, it is possible to see the ruins of special and unique buildings, aimed at their time to create spectacular places, to give appropriate spaces to the court and to the people living in this architecture masterpiece. The reading of these structures sometimes is not easy, so the main idea in this project is to start from the small evidences in the single buildings, find rules and solutions to combine them into a global digital survey based on a 3D digital model and then start using this model for hypothesis formulation. This kind of approach should only be multidisciplinary combining the knowledge about petrographic, mineralogical and chemical characterization with the techniques of the digital survey (using 3D Laser Scanner based solutions) and the reading of the architectural aspects. The research presented here will propose this methodological approach as the tool to interpreter the different construction phases of the Heliocaminus baths (II Century A.D.): the first personal spa of Emperor Hadrian.
Using mineralogic-petrographic (by optical microscopy and XRD) and physical analysis a set of samples were investigated for their compositional aspects of the aggregate and of the pozzolanic binder of mortars, and their physical characteristics (real and apparent densities, open and closed porosity, water absorption kinetic, mechanical strength, etc.). These parameters, together with the analysis of the aggregate particle size and morphology, and a proper analysis of the relationships binder/aggregate, have shown a clear relationship between the physical-compositional characteristics of mortars and their function within the structure of the baths. Then, through the differential thermal analysis (TGA, DSC) it has been studied the hydraulic degree of mortars, which is also linked to the kind of aggregate and pozzolanic materials used.
All this has allowed us to detect some compositional discrepancies between the different mortars used in this building, even within the same room, highlighting how the Heliocaminus baths was carried out in several stages, with interruption of the construction works and with an evident change in the workers operating in its courtyard. All the gathered data, linked to the pointcloud 3D model of the Heliocaminus baths allowed an accurate location of all the meaningful traces of the story of this structure giving confirmations to the high architectural value of specific and innovative solution of that age. The contribution of the scientific analysis of the samples puts in evidence the importance of correct and innovative solutions in cultural heritage approach with proper technologies
Origin of Roman worked stones from St. Saturno christian basilica (South Sardinia, Italy)
Full text linkThe work aims to define the origin of the architectural stone elements worked by Romans and reused in the
St. Saturno Basilica, between the late Antiquity and Romanesque periods. Thus, different rocks (marbles,
various facies of limestones, volcanic rocks) used to construct the ancient building were sampled and analysed.
All the different kinds of stones were sampled from the Basilica, taking precise reference to the various
construction phases and structural changes of the monument occurred in the centuries.
The sedimentary and volcanic lithologies belong to the local outcrops of Cagliari Miocenic geological formation
(e.g. limestone) and to other volcanic outcrops of south Sardinia, respectively. By means of a multimethod
archaeometric study (mineralogical-petrographic observations on thin sections and 18O vs 13C stable
isotope ratio analysis), the provenance of classical marbles used for manufacturing Roman architectural elements
(column shafts, bases, capitals, slabs, etc.) were defined, which are thought to come from extraregional
sources.
The results show that the marbles come mainly from Apuan Alps (Italy) and subordinately from Greek
quarrying areas
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