Experimental Rock–Water Interaction

Quantification of the interaction between minerals, rocks and groundwater or porewater requires data about the thermodynamic, kinetic and transport properties of the solid and liquid phase. The scientific literature provides generic data about these properties. In reality, however, such generic data may not be applicable to a specific problem of rock-water interaction. The absence of such data renders the prediction of rock-water interaction processes into the past and future uncertain.

To overcome these shortcomings we conduct in our laboratories experiments of increasing complexity from simple batch experiments to column experiments, various diffusion experiments to far advanced advective displacement experiments.

Such experiments allow us – among others – to determine the solubility of a specific mineral phase, the characterisation of natural attenuation and development of remediation strategies for groundwater contaminants, solute diffusion coefficients in different rock types, and the composition of porewater in aquitard lithologies.

Imposing a hydraulic gradient with an artificial pore water on a well-preserved drill core sample allows to (1) first sample aliquots of relatively undisturbed in situ pore water, and (2) measure tracer breakthrough over extended periods of time to derive hydraulic and transport properties.

Diffusion experiment conducted in our Experimental and Geochemical Labs aim at the derivation of porewater chemical and isotope concentrations of low-permeability rocks and diffusion coefficients for chemically conservative natural tracers.

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Prior to any analysis of its chemical composition, porewater has to be extracted from the rock matrix, which is not trivial in the case of low-permeability rocks such as claystones or crystalline rocks.

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Interfaces of clay-based materials (claystone, bentonite) and granite with cementitious materials are reactive and induce mineralogical alteration,  porosity changes and thus modify transport and retention properties for dissolved species.

Concentrations in aquifers and pore water of many environmentally relevant species (metals, radionuclides) but also major components (sulphate) may be controlled by solubility of a corresponding mineral phase. Solubility experiments also serve to constrain thermodynamic data (equilibrium constant, speciation) of solids and solid solutions.

Advanced polymer materials make it possible to construct X-ray transparent equipment for experiments under confining pressure whereby mineral alteration, density changes and porosity redistribution can be recorded in situ while experiments are running.

Batch experiments are conducted for various extraction tests (aqueous, TVA, hot-alkaline etc.) and solubility experiments.

Column experiments are conducted to investigate the behaviour of metallic contaminants in the natural soil/Rock envirnoment as well in engineered materials such as reactive barrier infills.

Column experiments
Column experiments conducted to investigate the efficiency of Fe-metallic alloys on the reduction of CrVI in solution (Flury, PhD Thesis 2008).