Marcella Palomba

The bentonites in pelotherapy : thermal properties of clay pastes from Sardinia (Italy)

Abstract On the basis of a previous detailed characterization of the Sardinian bentonites for pelotherapy applications [Cara, S., Carcangiu, G., Padalino, G., Palomba, M., Tamanini, M., 2000. The bentonites in pelotherapy: chemical, mineralogical and technological properties of materials from Sardinia deposits (Italy). Appl. Clay Sci. 16, 117–124 (this issue)], three commercial bentonites have been selected for detailed studies. The thermal properties of the pastes, prepared with these bentonites at different moisture, have been compared with the properties of a peloid, commonly used in the spa of Benetutti (northern Sardinia). The cooling kinetics of the bentonites along with the thermal mud have been studied using an experimental apparatus that reproduces the conditions during the application of a cataplasm. A mathematical model for the cooling kinetics has been obtained by means of a theoretical cooling equation, with instrumental constants derived from a reference paste (TiO 2 at 50% moisture). The heat capacity of the pastes introduced into the model was calculated from chemical and mineralogical data. The methodology developed can be used in other laboratories of the thermal centres to determine the quality and ability of the bentonitic materials for pelotherapy.

The bentonites in pelotherapy: chemical, mineralogical and technological properties of materials from Sardinia deposits (Italy)

Abstract Bentonite muds are suited for use in pelotherapy due to their typical properties of high swelling (>25 ml/2 g), specific heat (Cp) and ease of handling, generally obtained at a material viscosity of 400 cps. This paper reports chemical, mineralogical and technological properties of Sardinia bentonites, to identify the most suitable materials for pelotherapy pastes. Their characteristics have been compared to the peloid properties commonly used in the spa of Benetutti (Northern Sardinia). On the basis of the mineralogical, chemical and technological characterization of the samples, besides their proximity to the most important regional spas and/or thermal sources, Costa Paradiso, Pedroseddu, Laconi, Busachi, Siurgus-Donigala and Giba bentonites are the most suitable Sardinia materials for pelotherapy. The results of this study also show that a complete characterization of clay materials is necessary in pelotherapy paste preparation. The utilization and/or addition of bentonites, largely available in Sardinia at relatively low cost, can improve the thermal mud quality for curative purposes.

Geochemical, mineral-petrographic and physical-mechanical characterization of stones and mortars from the Romanesque Saccargia Basilica (Sardinia, Italy) to define their origin and alteration

This paper aims to study the geomaterials of the most important Romanesque-style monument of Sardinia, the Santissima Trinita di Saccargia Basilica (Codrongianos, north Sardinia). The monument was built up on ruins of a pre-existing monastery, and completed in 1116 A.D. Over time, the aspect of the monument is quite changed due to two series of restoration works. The stone materials consist of both grey-black basalts and whitish limestones and marls, intentionally used to give a bichromy effect of the construction. The volcanic rocks belong to the Miocene-Pleistocene volcanic Sardinian activity, while limestones and marls belong to the sedimentary marine Miocene Formation of Meilogu (Logudoro).To define both the origin and the alteration processes of materials, geochemical, petrographic and physical-mechanical investigations of volcanic and sedimentary rocks were carried out on samples collected from monument and possible source outcrops.The integrated chemical (ICP-MS) and petrographic data allowed to ascertain the sourcing sites of raw materials. Moreover, physical-mechanical tests along with X-Ray Diffraction (XRPD) analysis, highlighted the main weathering processes responsible of the chemical-physical alteration affecting the geomaterials, and the newly-formed mineral phases formed on stone surface.

Durability of repair mortars used in restoration of a Sardinian coastal tower: assessment after ten years

This study reports the results of investigations on conservation conditions of an ancient tower, called Torre del Pozzo, located in the S-W coast of Sardinia, restored about ten years ago. The tower suffers from serious problems related to vulnerability of building materials, particularly limestone and sandstones and aerial lime mortar with poor physical-mechanical properties. Over the centuries the materials were subjected to aggressive actions (wind corrasion and salt crystallization) causing an intense erosion of the walls with consequent partial collapse of the structure. About ten years ago a restoration involved the mortars and only the replacement and integration of ashlars deteriorated. After about 10 years from this intervention, some inspections have been carried out in order to assess the effectiveness of the intervention and the state of preservation of the tower. This paper focuses on analyses and tests carried out to assess condition and durability of the repair mortars. DOI: http://dx.doi.org/10.4995/FORTMED2015.2015.1761

Methodological approach in the conservation of coastal fortifications

The historical and artistic value of Coastal Towers justifies the recovery of these emblematic artifacts. For the achievement of this objective we propose a methodological approach including: i) architectural relief also by 3D laser scanner and collection of historical data; ii) macroscopic semi-quantitative evaluation of the decay, iii) application of diagnostic quantitative chemical-physical-mechanical methodologies, to assess the decay intensity, and define the criticalities for planning the restoration. The i step allows the graphic rendering of the building showing the geometry and the relationships between the parties. The ii step allows a preliminary understanding of the building materials, macroscopic alteration forms, monument features, acquisition of information about potential causes and decay mechanisms. During the iii step, sampling of building materials is planned. Laboratory analyses, to determine the soluble salts, crystalline phases, porosity as well as micro-textural features of the materials, are carried out by the application of suitable techniques. DOI: http://dx.doi.org/10.4995/FORTMED2015.2015.1752

Geomaterials and decay forms of the coastal towers of Piscinni and Foghe, Weastern Sardinia

The distribution of Coastal Towers in Sardinia testify that foreign invasions, which occurred several times over the centuries, were particularly frequent and dangerous. The beginning of the eighth century signed an increase of the attacks from the sea. The most of Coastal Towers were built in the period of Spanish rule, from 1583 to 1720. Despite numerous restorations over the years, many of these defensive structures are in critical conditions, some also affected by structural collapse. The building materials are closely related to local geological outcrops, and consist of sedimentary, magmatic and metamorphic rocks. Study of different lithotypes allowed assessing the vulnerability of different materials in different environmental conditions. Salts, transported by aerosols and deposited inside the porous structures, are the principal cause of decay of the building materials. Chemical-physical and mineralogical-petrographic analyses, performed on some Towers allowed making some general assessments on their conservation status and restoration projects. DOI: http://dx.doi.org/10.4995/FORTMED2015.2015.1753