The application of the µ-XRF method for determining the cement content reliably requires a robust routine for the evaluation of mappings. This phase analysis routine was to be worked out and tested in this project. Systematic investigations showed whether fine fractions of the aggregate would influence this analysis. Furthermore the µ-XRF-spectra were evaluated in a chemometric way in order to estimate the type of cement used.
The wet chemical determination of the cement content and the type of cement was strongly dependent on the solubility of the aggregate in EDTA, HNO3 or HCl. As set aside samples of the aggregates were not often available for analysis, a method for extraction of the aggregates out of the concrete in question was tested. It was evaluated, whether the solubility and the density of the extracted aggregate corresponded to the pure aggregate. For extraction the electrodynamic fragmentation was used. It was tested whether the grading curve was influenced by the electrodynamic fragmentation. As a second approach an image analytic method based on the above mentioned µ-XRF investigations was followed to analyse the grading curve of the aggregates.
The project contributed to obtain a reliable testing method of hardened concrete and to proof the compliance with standards specifications.
