ANANALYTICAL STUDY OF MARBLE CONSOLIDATION BY OXALATE PRECIPITATION USING DENSITY, FTIR AND POWDER-XRD MEASUREMENTS

Our recent study on consolidation of marble samples with the purpose of culture heritageprotection occurred by periodical calcium oxalate precipitation on top of quasi parallelepipedicsamples. The overall process consisting of three stages of treatment, starting with 5 % calciumacetate solution for 60 minutes at 20°C, a draining step at 70°C for 30 min, followed by a treatmentwith 5 % ammonium sulfate solution, it followed with the third stage which includes the treatmentwith 5% ammonium oxalate solution revealed a continuous density increace, determined usingethanol. As the natural samples had an initial density of 2.5871 g/cm3, it increased up to 2.6980g/cm3 for 50 times treatments. The precipitation of oxalate on top of calcium carbonate substrate, inform of calcite, revealed two distinguished infra-red bands, at 1316 cm-1and 1624 cm-1unsymmetrically located around the carbonate one at 1426 cm-1.The intensity of the bands wasproportional to the number of treatments. The continuous surface coverage investigated in parallelby powder XRD evidenced the presence of whewellite crystallites deposited on top of calcite, andtheir intensity increasing as well with the number of treatments. This method exhibits a reliableoxalate coverage of marble sample surfaces which doesn’t influence considerably their watersolubility.

Development of Stand for Rock Material Fracturing in Laboratory Conditions

The paper presents a description of the stand for rock material fracturing in laboratory conditions. Requirements to be met by fracturing stands were formulated. Proper operation of the test stand was verified by marble sample fracturing. Many of technical details of the developed stand were given, which may be useful for readers designing their own stands.

Temperature Induced Internal Stress in Carrara Marble

Stone physical weathering, deterioration and damage (e.g. bowing, cracking, microfracturing) represent a serious problem for preservation of sculptural and architectural heritage objects. Although different mechanisms of such degradation might be responsible (e.g. chemical or biogenic), there is an understanding in the geological community that physical reasons for stone degradation and role of stress are of primary importance. In this work Carrara marble was a chosen for investigation: a calcitic type with ~20% of dolomite. Neutron diffraction was used to investigate the phase composition, the texture, and the strain/stress in calcite and dolomite phases in a bulk marble sample. Evolution of the stress state was studied by measuring strains in calcite and dolomite at two temperatures with clear evidence of thermally induced microstresses. Results are discussed in connection to the theory of composite materials and a micro-mechanical explanation of the general problem of marble deterioration is suggested.

Test on Meso-Damage Data of Marble under Dynamic Load

The failure damage of granite under axial load are caused by the propagation and coalescent of cracks at mesoscale, so it is of important theoretical value and practical significance to to understand the mechnical properties of rock by experimental research on meso damage of granite. The microfracturing process of the pre-crack marble sample on surrounding rock in immerged Long-big tunnel in Jinping Cascade II Hydropower Station under uniaxial compression is recorded by using the testing scheme. According to stereology theory, the propagation and coalescent of cracks at meso-scale are quantitatively investigated with digital technology. Therefore, the basic geometric information of rock microcracks such as area, angle, length, width, perimeter, is obtained from binary images after segmentation. The results show that the new meso-mechanical testing scheme on rock meso-damage could be used to quantitatively analyzed from the geometric information of rock microcracks.

Meso-Mechanical Testing Scheme on Rock Meso-Damage Based on Digital Image Processing Technique

The failure damage of granite under axial load are caused by the propagation and coalescent of cracks at mesoscale, so it is of important theoretical value and practical significance to to understand the mechnical properties of rock by experimental research on meso damage of granite. The microfracturing process of the pre-crack marble sample on surrounding rock in immerged Long-big tunnel in Jinping Cascade II Hydropower Station under uniaxial compression is recorded by using the testing scheme. According to stereology theory, the propagation and coalescent of cracks at meso-scale are quantitatively investigated with digital technology. Therefore, the basic geometric information of rock microcracks such as area, angle, length, width, perimeter, is obtained from binary images after segmentation. The results show that the new meso-mechanical testing scheme on rock meso-damage could be used to quantitatively analyzed from the geometric information of rock microcracks.