Röntgendiffraktometer
Final Report Abstract
The Bruker D8 Discover X-ray diffractometer system, equipped with a fast LynxEye detector and two mountable experimental reaction chambers (a controlled humidity and temperature chamber) have been used for improved characterisation of mineral reactions under controlled measurement environments. In addition the wet-cell method of Warr & Hofmann (2003) was further developed using the XYZ stage for the study of reactions occurring at the clay mineral - cement interface. Three main topics of investigation have been: 1. Predicting the swelling behaviour of clay minerals in underground repository sites. Contracted projects from the Swedish Nuclear Fuel company (SKB) and student theses have been conducted using the humidity chamber and wet-cell devices for investigating the swelling behaviour of MX80 bentonite prepared with varying packing densities and hydrated in pure and cement-altered waters. New knowledge on the rates and mechanisms of water-uptake in MX80 clay and the dependence on the bulk density of the material has been published by Perdrial & Warr. The equipment was extensively used to investigate the alteration mechanisms that occurred at the clay-cement interface in the underground repository test site at Aspö. 2. Developing new types of clay-based cements. As part of a FuE project (Förderung von Forschung- und Entwicklung) from the Land Mecklenburg-Vorpommern and together with our industrial partner, the equipment has found extensive usage in the experimental study of metaclay for developing new types of geopolymer cements. The high temperature chamber (Tmax. 1600°C) is used for studying in situ thermal dehydroxylation and decomposition reactions. First results have been presented. New types of clay-bearing concretes are also being developed in collaborative work with Luleå Technical University. Our XRD-studies have helped develop talc-bearing concretes for possible use in underground nuclear waste repositories. The talc is proposed as an alternative to organic superplastifers to avoid the release of unwanted colloids. 3. Characterisation of clay minerals reactions in mudrocks and shales. The equipment was extensively used to study the nature of clay minerals in mudrocks from a range of geological environments. Particular attention has been given to investigating the neoformation of clay minerals and the hydration states of smectites sampled i. from the seismically active fault zone of the SAFOD project, California, ii. from the Zechstein oil-reservoirs of northern Germany, iii. from the hydrothermally-altered Paleozoic basins of northern Spain and iv. from glauconite-bearing sedimentary rocks of central Germany. In these projects, the controlled humidty chamber and the Lynx Eye detector have proven to be useful tools for characterizing the swelling nature of the smectitic phases in relationship to water activity.
Publications
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(2011). Geoscientific applications of particle detection and imaging techniques with special focus on the monitoring of clay minerals. Handbook of Particle Detection (Editor C. Grupen), Springer
Warr, L.N. & Grathoff, G.
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(2011). Hydration of MX80 bentonite in a confined-volume system: Implications for backfill design. Clays and Clay Minerals, 59, 640-653
Perdrial, J.N. & Warr, L.N.
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(2012) BaMn[CO3]2 – a previously unrecognized double carbonate in brackish sediments: Structural, spectroscopic, and textural tools for future identification. Chemie der Erde 72, p. 85-89
Böttcher, M.E., Effenberger, H., Gehlken P.L., Grathoff G.H., Burkhard C. & Schmidte, B.C.
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(2012). Chlorite-smectite clay minerals and fault behaviour: New evidence from the San Andreas Fault Observatory at Depth (SAFOD) core. Lithosphere, 4, 209-220
Schleicher, A.J., van der Pluijm, B. & Warr, L.N.
