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Bourgès, Ann (2006): Holistic correlation of physical and mechanical properties of selected natural stones for assessing durability and weathering in the natural environment.. Dissertation, LMU München: Faculty of Geosciences
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Abstract

The main purpose of this study is to understand influences of bulk structure of materials on strength behavior as well as water storage and transfer in order to assess durability and weathering. Therefore, a selection of different methods are applied and compared to optimize the understanding of material structure and physico-mechanical behavior. Optical microscopy (Digital Image Analysis) and scanning electron microscopy as well as water vapor permeability, biaxial flexural strength and ultrasonic velocity are measured on different natural materials: sandstones with clayey, silicious or calcareous binder, oolithic and micritic magnesian limestones and a thermally aged Proconnesian marble. Microstructurales and macrostructurales properties of these materials are studied before and after artificial weathering (freeze-thaw cycles). First, and in order to validate the efficiency of the digital image analysis to characterize porosity and structure, traditional porosity measurements as water ad- and absorption and mercury porosimetry are crosschecked with the result obtained from digital image analysis. Limits of each methods are also defined. Then, validations of non-destructive and semi-destructive methods are also pursued to evaluate their potential value to replace and complement standardized methods. By analysis of linear correlations, some essential mechanisms should be underlined, which may connect the macrostructure to the microstructure of the material. A systematic method of analysis should clearly appear and emphasize the role of the structure (grain size, grain contact and pore shape) on physical and mechanical behavior. The main parameters leading to weathering should then be identified and models of correlations drawn. Correlations between the various physico-mechanical properties could ameliorate the possibilities to assess durability and weathering in the natural environment.