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The distribution of smectites in altered basic rocks and its implications for road constructions

In a recent work we could show that smectites grown in altered basalts relate to inadvertent deterioation of rock aggregates used in road construction. Interestingly, the smectite contents determined by X-ray diffraction were consistently higher than those calculated from measurements of the cation exchange capacities, which was qualitatively interpreted by different kinds of occurrences of smectites in these rocks: finely disseminated smectite and smectite aggregates. A clear distinction in thin sections, however, is not feasible due to its fine-grained nature and its association with other non-swelling clay minerals. The aim of this work is to analyse the two-dimensional smectite distribution with a FTIR microscope and try to relate the kind of distribution with mechanical properties such as disaggregation tests with dimethylsulfoxide. The results may proof our hypothesis that smectite contents per se are not necessarily an exclusion criterion for using the rocks in road construction.

Start of work: Immediately
Supervision: Helge Stanjek, Dirk Prinz (LEK), Andre Hellmann (IML)
Level: BSc, MSc, AGW preferred