Reverse engineering methodology for studying historic buildings coatings: The case study of the Hellenic Parliament neoclassical building

In this work a reverse engineering methodology for the study of historic buildings coatings is presented. This includes different stages: characterization and evaluation of historic coatings, criteria and methodology for the selection of raw materials and the production of restoration coatings, criteria and procedure for the evaluation of restoration coatings and evaluation of coatings during setting and hardening. The proposed methodology was applied for the study of the Hellenic Parliament building. More specifically in order to recognize and map the original historic coating non destructive techniques were used, such as fibre optics microscopy, infrared thermography, ultrasonic technique and ground penetrating radar. The chemical composition of the original coating, its decay and its production technology, were assessed by granulometric and thermal analysis, as well as by X-ray diffraction. Additionally the colorimetric values of the coating were assessed, using the L*a*b* colour space. It was found that the colourization resulted by a crushed stone, used as aggregate, without the addition of any pigments. Based on these data, various compositions of restoration coatings were prepared and tested. Their evaluation was performed based on compatibility criteria with the historic coating.