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- Lindqvist, Jan-Erik, et al.
(author)
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Assessment of mechanical durability properties of rock materials using quantitative microscopy and image analysis
- 2003
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Reports (peer-reviewed)abstract
- This report presents a project that focuses on the assessment of mechanical durability properties using quantitative microscopy. The project was financed by SGU under grant 03-1174/98. The aim has been to develop methods for assessment and presentation of rock quality data. Both optical and SEM/BSE microscopy were applied and combined with computerised image analysis and manual methods for the quantitative analysis. The first part of the project was to produce a literature overview of image analysis as applied to rock materials. A method for assessment of resistance to fragmentation of granitic rocks comparable with the Los Angeles test has been developed. By means of a quantitative description of foliation using a foliation index, FIX, it is possible to assess the potential length-thickness ratio of the crushed aggregate. Methods developed in the main part of the project have been applied in related areas. These include crack initiation and propagation under cyclic loading and cyclic thermal stress.
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| 2. |
- Malaga, Katarina
(author)
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Consolidation of Gotland sandstone
- 2004
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In: 10th International Congress on Deterioration and Conservation of Stone.
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Conference paper (peer-reviewed)
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| 4. |
- Malaga, Katarina, et al.
(author)
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Field exposure sites and accelerated laboratory test of marble panels
- 2004
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In: Proceedings of the international conference on Dimension Stone 2004, 14-17 June 2004, Prague, Czech Republic. - : Taylor & Francis Group plc, A.A Balkema Publishers.
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Conference paper (peer-reviewed)abstract
- The use of thin marble and limestone for facade cladding has increased substantially during the last five decades. The durability of thin slabs (often only 30 mm thick) has been assumed to be satisfactory based on centuries of successful use as a structural building stone. Nevertheless, all over the world, the long-term deformation and strength loss of some claddings have led to concerns about its safe and durable use. The detailed assessment of marble and limestone within TEAM (see also www.sp.se/building/team) is used to develop a hypothesis for the observed deterioration and to develop remedial actions. This paper describes the field exposure sites, the accelerated test, and presents parts of the results. The results indicates that all marbles bow, but at different magnitudes. The marbles demonstrate diurnal and seasonal variation in bowing and dependence on the thickness and impregnation. The final evaluation of the results will be presented in 2005.
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| 8. |
- Malaga-Starzec, Katarina, et al.
(author)
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Efflorescence on thin sections of calcareous stones
- 2004
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In: Journal of Cultural Heritage. - : Elsevier BV. - 1296-2074. ; 4:4, s. 313-318
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Journal article (peer-reviewed)abstract
- Limestone and marble, still frequently used as building materials are especially vulnerable to the destructive effects of efflorescence. The effect of interaction between five different calcareous stones and corrosive atmospheres has been investigated. A novel technique of stone degradation analysis has been used where thin sections of fresh stone materials were exposed in a corrosion chamber under controlled conditions (temperature, relative humidity (RH), SO2 and NO2 concentration). Following 1-weeks exposure; observations of the initial crystallisation were studied by light microscopy, scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD). The results obtained from the surface analysis clearly showed sulphation of the samples and formation of gypsum. Observations of the initial corrosion indicated differences in the location of efflorescence and its shape among and within the samples. The mineralogy, grain shape and size, mineral defects and existence of cracks and pores, all influenced the substrates reactivity. The most vulnerable areas and the places where the corrosion started on the calcitic stones were the triple grain junctions followed by grain boundaries, and on the dolomitic marble cracks and pores.
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| 9. |
- Malaga-Starzec, Katarina, et al.
(author)
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Model study of initial adsorption of SO2 on calcite and dolomite
- 2004
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In: Applied Surface Science. - : Elsevier BV. - 0169-4332. ; 222:1-4, s. 82-88
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Journal article (peer-reviewed)abstract
- The rate of calcareous stone degradation is to a significant extent controlled by their surface chemistry with SO2. Initial surface sulphite is converted to a harmful gypsum upon, e.g. NO2 catalysed oxidation. However, it has been observed by scanning electron microscopy that the lateral distributions of gypsum crystals differ between calcitic and dolomitic marbles. The first-principles density functional theory is employed to understand the origin of these fundamentally different morphologies. Here, the stability differences of surface sulphite at calcite CaCO3 (s) and dolomite CaxMg1-xCO3 (s) are determined. A qualitative difference in surface sulphite stability, favouring the former, is reported. This is taken to imply that calcitic microcrystals embedded in a dolomitic matrix act as sinks in the surface sulphation process, controlled by SO2 diffusion. The subsequent formation of gypsum under such conditions will not require SO42+ (aq) ion transport. This explains the homogeneous distribution of gypsum observed on the calcitic micro-crystals in dolomite. In contrast, sulphation on purely calcitic marbles never reaches such high SO2 Coverage. Rather, upon oxidation, SO42+ (aq) transport to nucleation centres, such as grain boundaries, is required for the growth of gypsum crystals.
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