Methodology

A - Investigation

A1) subdivision of the territory

On the base of indications of the Town Development Plan the territory has been subdivided into homogeneous zones in relation to the historical and typological features of buildings. Inside these zones have been identified some homogeneous sub-zones for building and road typologies.  

A2) abacus of the deteriorations

In this phase it have been identified, inside the zones and sub-zones (1) the principal pathologies, the constructive defects, and how much other competes to the physical and aesthetical deterioration of the external surfaces in consideration, also, of erroneous customs of intervention. Particular attention has been turned to the different exposure to the sun, to the position in comparison to the sea and wind, to the presence and the extension of the before spaces, to the height of the before buildings, to the dimension of the roads and the alleys, to the presence and the intensity of the vehicular traffic.  

A3) identification of the pathological phenomena to submit to laboratory analysis (chemical, physical, mineralogical). For some pathologies related to the constructive components of Ortigia - for instance the peculiar phenomenon of alveolar erosion on the local stones - sampling and analysis have been conducted, edited by the C.N.R. laboratories, with the purpose to identify the nature of the pathologies and to establish the methodologies of intervention more fit.   

A4) abacus of the techniques

The different techniques and materials (traditional and actual) used for the retraining of the external surfaces have been examined - In this phase,   have been identified systems of intervention as exposed in the following section B (2)

B - Experimentation

B1) In situ experimentation.

Evaluation of materials and techniques of intervention - In this phase some manufacturers have been invited with the purpose to experiment (under narrow control and near two building samples from local government) the products and the techniques, to submit to analysis according to the suitable procedures in the following sections B2-B3.   In situ experimentation has been started, through the realization of interventions set under critic atmospheric conditions on the external hangings of the building samples.

B2.1) Scientifical analyses

B2.2 Characterization of stones and identification of cause and size of deterioration.

B.2.2.1 Natural stones (qualification of the stones, quarry of origin, deteriorations):

  • Mineralogical / petrographic survey (XRD diffraction, mineralogical microscope on thin section); Chemical investigations (conductimetry, UV/Vis-IR spectrophotometry, ionic chromatography)
  • Micro structural and microanalysis survey (optical microscope, scanning electronic microscope with microprobe both on external surface and on fracture, stratigraphy)
  • Physical survey (mercury porousimetry , absorption water for capillarity, for immersion, evaporation, permeability)
  • Biological survey (identification of the factors of bio deterioration: analysis of lichen flora, coltural analysis for micro organisms; optical and scanning electronic microscopy, ionic chromatography, X-diffractometry)

B.2.2.2 Artificial stones (plasters, mortars):

  • Mineralogical - petrographic survey (XRD diffraction, mineralogical microscope on thin section, image analysis, stratigraphy)
  • Chemical survey (atomic absorption spectrophotometry, ionic chromatography, FTIR spectrophotometry , calcimetry, Raman spectrophotometry, plasma spectrophotometry)
  • Micro structural survey (optical microscopy, scanning electronic microscopy with microprobe, micro FTIR spectrophotometry on external surface, stratigraphy)
  • P hysical survey (porousimetry)
  • Biological survey (identification of the factors of bio deterioration : analysis of lichen flora, coltural analysis for micro organisms; optical and scanning electronics microscopy, ionic chromatography, X diffractometry)


B.2.2.3 Hygrometric status of the structures:

  • G ravimetric measurements (distribution map of hygrometric contents at different levels and depths)

B.2.2.4 Atmospheric Pollution:

  • Qualitative and quantitative identification of atmospheric pollutants and search for the "historical data


B.3) reliability and effectiveness of proposed systems for working.

  • Critical analysis of technical schedules provided by the manufacturers (experimental tests in situ B.1) concerning with products and application methodologies (cleaning, puttying, consolidation, protection). For technical schedules of products considered few exhaustive, qualification, tests have been carried out in laboratory (X diffractometry, qualitative and quantitative recognition of possible soluble salts contained in the product, microprobe scanning electronic microscope observations, IR spectrophotometric analysis, etc.).   ·   informative schedules and questionnaires on the Manufacturers for an evaluation of their professionalism, knowledge and experience in the conservative sector, etc.  
  • Execution in laboratory of analyses that have been made necessary for better evaluation of the products (and of the methodologies of intervention) or as verification of the features described in the technical schedules (X diffraction, qualitative and quantitative recognition of possible soluble salts, observations on scanning electronic microscope equipped with microprobe, I.R. spectrophotometric analysis, chromatographic analysis, possible chemical-physics interference with stones).
  • Mortars for plasters - in situ execution of physical, chemical and mechanical trials (first and after the application) to evaluate the adhesion of the plaster to the underlying structure (ultrasonic mapping, coring in depth) or, in the case of special salt-extracting plasters, qualitative and quantitative evaluation of the water soluble salts with relative mapping, evaluation of the thermo-hygrometric contents with relative mapping).
  • Methods of cleaning for the stones - tests for the evaluation of the effectiveness and not harmfulness vary in relation to the method of select technique.
  • Consolidants and protective materials - tests have been performed (first and after the application) for the evaluation of the chromatic modifications of the stones (colorimeter), of the consolidant action (abrasive method), of the protective action (water absorption according to the method Karstern's test tube).
  • Evaluation of the effectiveness of biocide-action products. Visual observation "in situ" (vegetation and lichens), coltural analysis (autotrophyc and eterotrophyc micro-organisms) , epifluorescent microscope analysis (photo autotrophyc micro-organisms and lichens).
  • Checking of the effectiveness of systems of improvement of the masonries from the damp. Measures of the content of damp of the masonries at different levels and depths ( Normal 40/93); dosing of the soluble salts at different levels and depths (Normal 13/85); comparison between measures of the content of damp before and after the application.

(1) The analysis on the historical buildings, the individualization of the micro-climatic zones and the macroscopic recognition of the surfaces  have been performed by the arch.Teresa Campisi.

(2) Particular attention has been set in the investigation on the plasters (they show the most remarkable damages), about the techniques to oppose rising damp (electro-osmosis, hydrophobic and mechanical treatments), about the systems of cleaning of the stones (chemical packs, water spray nebulization, micro-grit blasting, Joss-blasting, Nd:YAG Laser) of consolidation (ethyl-silicate impregnation) and of protection (water-repellent treatment using silicon-organic chemicals) of the stones.

 

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