This study focuses its attention on the chemical treatment of marble samples in order to create conditions for the protection of cultural heritage objects that consist of these materials. Water penetration, or its vapor condensation in the pores of these material leads to the formation of crystalline ice embryos, which depending on the environmental conditions create internal tensions and disrupt their micro-structure. Their consolidation was carried out by a three stages treatment, starting with 5 % calcium acetate solution for 60 minutes at 200 °C. The second stage occurs after a draining step at 700 °C and for 30 min, and involves the samples treatment with 5 % ammonium sulphate solution. After the application of the same draining procedure as previous, it followed with the third stage which includes the treatment with ammonium oxalate, followed by the same draining procedure. The marble samples were subjects of: 10, 20, 30, 40, and 50 treatments respectively, revealing each time weight increase. Their porosity and specific surface area, assessed by gas porosimetry measurements, continuously decrease at until the last treatment.
- Klíčová slova
- mramor,
- MeSH
- kyselina oxalová MeSH
- minerály * MeSH
- povrchové vlastnosti MeSH
- testování materiálů * MeSH
In the present study the treatment by three chemical solutions (5%) of travertine is considered. The overall process assumes the structural pore reduction due to the continuous controlled crystallization of low soluble inorganic salts such as calcium sulfate and calcium oxalate. Travertine samples of monolithic blocks of Turkish origin previously cut in form of parallelepiped blocs with length of 25 ± 1mm, width and thickness of 7 mm are employed in this study. The prepared samples were dipped in distilled water for 2-3 hours followed by drying up to 6 hours at 70 °C, 6 hours at 100 °C and 12 hours to 125 °C. Consolidation of travertine samples is carried out by treatment in three stages: the first stage involves treatment with calcium acetate (Ca(CH3COO)2• H2O), the second stage involves the treatment with ammonium sulphate (NH4)2SO4 followed by the third stage includes the treatment with ammonium oxalate (NH4)2C2O4•H2O. The decreasing of porosity and surface area is monitored by continuous gravimetric measurements followed by gas- and mercury porosimetry measurements. After each treatment, the sample weight increases and its porosity decreases. All samples were subject of: 10, 20, 30, 40, 50 treatments respectively.
