Data publication: FuE-Vorhaben FUNGUS: μCT-Parametrisierung und Bewertung des Sorelbeton-Wirtsgesteinskontakts des Versuchs-Halbdammes aus dem Projekt STROEFUN III

During the STROEFUN III R&D project, an experimental semi-dam seal structure made of MgO-concrete was built in the rock salt mining area of the Teutschenthal mine. The contact zone between host rock and concrete, as possible weak component of the barrier, is of major concern. Initial samples from the STROEFUN III project indicated small-scale zoning in the centimeter range with significantly increased porosity in some cases in the contact area, as well as joints with opening widths in the millimeter range.

Within the framework of the follow-up project “FUNGUS”, µCT investigations of drill cores (diameter 50-100 mm) from different locations, mainly from the contact, were conducted to characterize this contact zone.

The µCT images were taken using a Nikon XT H 225 scanner. The imaging parameters were typically: U = 220 kV, I = 150–180 µA, filter: 3 to 6 mm Cu. The filter is used to adjust the X-ray spectrum and optimize image contrast. Strong filtering causes hardening or monochromatization of the X-ray spectrum, which reduces the effect of absorption dispersion.

Tomographic reconstruction was performed using the OEM software CTPro3D, including a beam hardening correction to compensate for the absorption dispersion, which depends on the X-ray spectrum and the thickness of the material being irradiated.

The resolution of the measurement depends crucially on the distances between the source, object, and detector. The voxel size calculated from this can be regarded as an estimate of the resolution.

Unfortunately, the tomograms showed ring artifacts, probably due to random detector errors. They were reduced by appropriate post-processing. This post-processing was conducted with Avizo (Fisher Scientific), applying

• Ring Artefact Removal

• Gray Scale Normalization

• 3D-Non-local Means Filtering

• Eventually rotation and resampling

• Eventually Beam-Hardening-Correction or Background Correction

These enhanced raw-images are included in this repository as 7z-compressed binary files, see FUNGUS_data.pdf for details.

Also included are sample images (png-format)