Identifying construction materials is the starting point for the recognition of degradation mechanisms and typologies and is essential for the correct planning of restoration interventions. In particular, mineral-petrographical and chemical studies on materials make it possible to examine a number of extremely important problems, such as those related to composition, origin, production technology and state of conservation. By identifying the types of degradation present, it is indeed possible to discover the causes leading to their formation and intervene to eliminate their effects with appropriate maintenance and restoration projects. In the case of the Church of St. Francis, the aim of the diagnostic project was to obtain information on the nature and origin of the natural stone materials, the techniques used to prepare artificial stone materials (brick) and the state of conservation. Mainly brick is used on the façade, with colours ranging from red to pinkish red. Stone is used only to a limited extent for the columns, capitals, arches, bases, steps and shelves. The state of conservation of the façade varies with widespread deposits, black and white areas and phenomena of erosion. Extensive con- sistent yellowish deposits, cracking, gaps, dripping, engravings and graffiti are also present. Various architectural elements had been replaced, above all at the bottom of the façade, creating a certain irregularity in the interpretation of the structure. The diagnostic project entailed the collection of representative micro-samples of the structure investigated, without altering the formal and aesthetical appearance in any way. The specimens underwent the following studies: optical microscopic (OM) mineral-petrographical examination and x-ray diffractometry (XRD) mineralogical analyses. The investigations carried out on natural stone materials led to the identification of different local lithotypes: Bugarone, Red Shingle and Sandstone of St. Hippolytus. Although the colour of the bricks varied to some extent, their composition was substantially similar. Deposits and black crusting consisted mainly of air particulate, gypsum, calcite, quartz and opaque minerals. The analysis of the state of conservation of the Church of St. Francis demonstrated a particularly critical situation requiring urgent restoration interventions, taking into account the nature of the materials, their characteristics and the surrounding environment. A knowledge of materials and degradation processes may help to develop specific conservation intervention systems in that this permits identifying the most appropriate products and technologies, from those available, for specific problems, preventing situations of incompatibility and ensuring their duration and resistance in time.

Criteri e modalità di indagine diagnostica sui materiali naturali e artificiali

AMADORI, MARIA LETIZIA
2015

Abstract

Identifying construction materials is the starting point for the recognition of degradation mechanisms and typologies and is essential for the correct planning of restoration interventions. In particular, mineral-petrographical and chemical studies on materials make it possible to examine a number of extremely important problems, such as those related to composition, origin, production technology and state of conservation. By identifying the types of degradation present, it is indeed possible to discover the causes leading to their formation and intervene to eliminate their effects with appropriate maintenance and restoration projects. In the case of the Church of St. Francis, the aim of the diagnostic project was to obtain information on the nature and origin of the natural stone materials, the techniques used to prepare artificial stone materials (brick) and the state of conservation. Mainly brick is used on the façade, with colours ranging from red to pinkish red. Stone is used only to a limited extent for the columns, capitals, arches, bases, steps and shelves. The state of conservation of the façade varies with widespread deposits, black and white areas and phenomena of erosion. Extensive con- sistent yellowish deposits, cracking, gaps, dripping, engravings and graffiti are also present. Various architectural elements had been replaced, above all at the bottom of the façade, creating a certain irregularity in the interpretation of the structure. The diagnostic project entailed the collection of representative micro-samples of the structure investigated, without altering the formal and aesthetical appearance in any way. The specimens underwent the following studies: optical microscopic (OM) mineral-petrographical examination and x-ray diffractometry (XRD) mineralogical analyses. The investigations carried out on natural stone materials led to the identification of different local lithotypes: Bugarone, Red Shingle and Sandstone of St. Hippolytus. Although the colour of the bricks varied to some extent, their composition was substantially similar. Deposits and black crusting consisted mainly of air particulate, gypsum, calcite, quartz and opaque minerals. The analysis of the state of conservation of the Church of St. Francis demonstrated a particularly critical situation requiring urgent restoration interventions, taking into account the nature of the materials, their characteristics and the surrounding environment. A knowledge of materials and degradation processes may help to develop specific conservation intervention systems in that this permits identifying the most appropriate products and technologies, from those available, for specific problems, preventing situations of incompatibility and ensuring their duration and resistance in time.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11576/2622198
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