Macro- and Micro- Non Destructive Tests for Environmental Impact Assessment on Architectural Surfaces
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Mat. Res. Soc. Symp. Proc. Vol. 462 ©1997 Materials Research Society
content (fig 3). A mercury porosimeter (FISONS Porosimeter 2000) was employed for the measurement of the Total Porosity, the Pore Radii distribution, the Bulk Density and the Cumulative Volume. The simulation model used was the cylindrical one (fig 2, Table 2). B. On site the following Non Destructive Tests have been performed: I- Digital Image Processing: The process of conversion from pictorial image to digital image, consists in the sampling of the function f(x, y) according to a square dot matrix and successive quantification of spatial samples codified in the binary system 5 (fig 1). 2. Fibre Optics Microscopy is applied in the field (by PICO SCOPEMAN - MORITEX), in several magnifications, X25, X50, XI00, X200. The images were stored in a video system, and they were processed in the laboratory (fig 1). 3. Infra Red Thermography (IR) is a measurement technique providing thermal maps. A thermographic system consists of an IR Detector (TVS - 2000 MK II LW) and a Processor (AVIO Thermal Video System). The IR Detector uses germanium optics with a peak coating at about 10 min, manufactured by mercury-cadmium-telluride (HgCdTe) which gives a spectral response between 8 and 14 pim wavelengths and requires a stirring cooler system (He gas 99,99%). The IR Detector is connected with a processor which detects the electronic signal, stores it in memory, processes it according to a given software and presents it in an LCDS, by the form of a thermograph (fig 4). The temperature range of an IR Detector spans from -400 C to +300 0 C. RESULTS AND DISCUSSIONS Digital Image Processing - Fibre Optics Microscopy In fig la,b and a,, b, correspondingly weathering mapping, natural (a, b) and digitally processed (a,b) images are presented rendering in false colors details of: 1. Masonry under alveolar disease (point 5), varying from desegregation to pitting, cavities, interconnected cavities and full face caves (a, a,). 2. Masonry presenting hard carbonate and biogenic crust (point 17a), partially replaced by new structural stones of different porositywhich triggers intense alveolation and salt decay at the interface(b,b 2) It is obvious that alveolar disease (a, a,) is rendered by different tonalities (maroon, violet, blue, black), than the ones (ochre grey-yellow) restituting hard carbonate crust (b, bj). Fibre optics micrographs (figlaz, b2) coordinated with scanning electron ones (figla 3, b3) accompanied by EDX analysis 2, show that : 1 In the case of alveolar disease (point 5) (fig I a2, a3), sodium chlonde crystals are growing within the pores, exerting pressures to the pore walls, which cause a breaking up of grain contacts. This has the effect of an enlargement of the small entry radii into the large intergranular pore space, continuously filled by NaCI crystals, Pore volume curves show pore size distribution per masonry height (5.1: 95m, 5.2: lm, 5.3: 1,5rm, 5.4: 2m) (fig 2a) It is evident that the more the granular disintegration proceeds, the more the por
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