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Jan Dewanckele, Ghent University (Belgium)
Veerle Cnudde, Ghent University (Belgium)
Yoni De Witte, Ghent University (Belgium)
Mattieu Boone, Ghent University (Belgium)
Denis Van Loo, Ghent University (Belgium)
Luc Van Hoorebeke, Ghent University (Belgium)
Patric Jacobs, Ghent University (Belgium)
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All monuments build with natural building stones are affected by weathering and controlled by the interaction between stone and external factors such as freeze-thaw cycles, biological activity, rain and pollution. Physical, biological and chemical weathering processes mainly proceed in the pore space and contribute to the disintegration of the stone. Precise knowledge of the pore characteristics is therefore essential. These characteristics are precursors of the weathering behaviour and durability of the natural stones. The pre-existence of micro cracks and anomalous cavities also control the deterioration of the stone. To obtain meaningful information on those geological parameters, X-ray computed tomography (CT) can be applied. CT is an excellent non-destructive research tool that can be used in a broad range of geological domains and contributes to the characterization of the internal structure of materials. When an X-ray beam passes through an object, beam intensity decreases due to absorption and scattering. By mapping the variation of X-ray attenuation within this object, a 3D reconstruction can be made. 3D visualisation and image analysis enable new approaches in petrochemical research and in characterising various natural building stones.
Although CT is an excellent technique for micro-structural research, it is limited concerning element distribution. Based on their attenuation coefficient alone, it is difficult to distinguish quartz from albite in a granitic rock. The combination of X-ray fluorescence (XRF) and high-resolution CT may provide an answer and characterise the element spatial and mineral distribution. The integration of the Morpho+ software tool provides a non-destructive, 3D quantification of the resulting data. Further research on this subject will be performed at the Centre for X-ray Tomography (UGCT) of the Ghent University in Belgium. We will present some experimental results of CT applied on natural building stones such as granite. In order to compare the results of this method, additional tests are performed with more traditional techniques including optical microscopy and scanning electron microscopy (SEM).
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