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- The evolution of the mineralogical and petrophysical properties of a weathered limestone in southern Belgium
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The evolution of the mineralogical and petrophysical properties of a weathered limestone in southern Belgium
Abstract
The weathering of limestone results in the partial dissolution of calcium carbonate and leaves a soft porous material called alterite. The properties of the weathered rock differ significantly from those of its parent due to the changes in composition and the removal of soluble materials. The resulting increase in porosity modifies the hydrological proprieties of the rock such as its permeability, hydraulic conductivity, and reservoir capacity. The loss of material also weakens the structure of the rock and decreases its mechanical resistance. This study quantifies the progressive changes in the mineralogical, petrographic and mechanical properties that occur during the weathering of the Carboniferous Petit Granit, a limestone found around Soignies in southern Belgium. The rock samples, representing various stages of weathering, were collected within the same stratum and analysed in terms of their porosity, permeability, density, carbonate content, and mechanical resistance. The mineralogical and petrophysical changes were documented through X-ray diffraction and thin sections analysis. It is clearly seen that weathering exerts a great influence on the rock properties: the widespread increase in porosity is associated with a decrease in density, a large increase in permeability, and a fall in the mechanical strength to zero. We show how these properties change with the intensity of the weathering.
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About: Caroline DUBOIS
University of Mons, Faculty of Engineering, Department of Geology and Applied Geology, Mons, Belgium. caroline.dubois@umons.ac.be,
About: Yves QUINIF
University of Mons, Faculty of Engineering, Department of Geology and Applied Geology, Mons, Belgium. yves.quinif@umons.ac.be
About: Jean-Marc BAELE
University of Mons, Faculty of Engineering, Department of Geology and Applied Geology, Mons, Belgium. jean-marc.baele@umons.ac.be,
About: Fabrice DAGRAIN
University of Mons, Faculty of Engineering, Department of Civil Engineering and Structural Mechanics, Mons, Belgium. fabrice.dagrain@umons.ac.be
About: John DECEUSTER
University of Mons, Faculty of Engineering, Department of Geology and Applied Geology, Mons, Belgium. john.deceuster@umons.ac.be
About: Olivier KAUFMANN
University of Mons, Faculty of Engineering, Department of Geology and Applied Geology, Mons, Belgium., olivier.kaufmann@umons.ac.be.