Читать книгу Monument Future - Siegfried Siegesmund - Страница 394

Petrographic analyses of the material were done on thin sections under a polarization microscope. Hydrostatic weighing on sample cubes of 65 mm edge length was carried out to acquire the particle and bulk density as well as the porosity (DIN 52102). The saturation degree S was determined by the 258quotient of unforced (atmospheric conditions) and forced (vacuum) water saturation. On sample cubes of 65 mm edge length, the capillary water adsorption (w value) was measured in a closed cabinet while weighing over time (DIN EN ISO 15148). Mercury intrusion porosimetry was used to acquire the pore radii distribution (Fig. 2g and h).

Figure 1: a) The Geghard Monastery complex, Upper Azat Valley. b) The prayer hall of the Kathoghike Church built from basalt. c) Rock cut tombs and cross stones. d) The Jamatoun of the Proshian cut into the rock.

The hydric expansion of the tuff rocks was measured on square samples (diameter 15 mm, length 100 mm) under conditions of complete immersion in demineralized water. A displacement transducer with a resolution of 0.1 µm measured the linear expansion as a function of time. Ultrasonic velocity was measured by using a pundipLap+ device (proceq). Surface hardness measurements were done in situ as well as on stone samples in the laboratory. For the measurements an Equotip 3 (proceq) portable testing device with an impact device D was used on dry and wet samples and at the onsite investiagtions.

Onsite investigations included damage mapping, surface hardness measurements, Karsten tube tests to detect the water uptake capacity, electrical capacity and conductivity. The investigations were done on the east façade of the Kathoghike Church (errected in 1215) and at the eastern wall of the Jamatoun of the Proshian (constructed in 1283). The latter consists of the rock cut structure (Fig. 1d, 3a).