Concept for retrospective determination of the concrete composition, the grading curve as well as further properties of aggregates or the cements in hardened concrete

The aim of the project is answering open questions of the finished project IGF 17829 N and to develop a method for determining the grading curve of aggregates in hardened concrete.

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 is to be worked out and tested in this project. Systematic investigations will show whether fine fractions of the aggregate might influence this analysis. Furthermore the µ-XRF-spectra are 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 is strongly dependent on the solubility of the aggregate in EDTA, HNO3 or HCl. As set aside samples of the aggregates are often not available for analysis, a method for extraction of the aggregates out of the concrete in question should be tested. It will be evaluated, whether the solubility and the density of the extracted aggregate corresponds to the pure aggregate. For extraction the electrodynamic fragmentation will be used. It will be tested whether the grading curve is influenced by the electrodynamic fragmentation. As a second approach an image analytic method based on the above mentioned µ-XRF investigations is followed to analyse the grading curve of the aggregates.

The project is going to contribute to obtain a reliable testing method of hardened concrete and to proof the compliance with standards specifications. 

Supported by

The IGF project 19475 N of VDZ gGmbH was supported by the AiF within the framework of Industrial Collective Research (IGF) of the Federal Ministry of Economic Affairs and Energy on the basis of a decision of the German Bundestag.