Dynamic 4D imaging of foamed bitumen by X-ray micro ... · Dynamic 4D imaging of foamed bitumen by...
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Dynamic 4D imaging of foamed bitumen by X-ray micro computed tomography Iwan JERJEN1,2, Biruk HAILESILASSIE3, Philipp SCHUETZ5, Mathieu PLAMONDON4, Alexander FLISCH4, Manfred PARTL3
1) Institute for Biomedical Engineering, ETHZ, Gloriastrasse 35, CH-8092 Zurich, Switzerland
2) Laboratory for Macromolecules and Bioimaging, Paul Scherrer Institut, CH-5232 Villigen-PSI, Switzerland
3) Road Engineering/Sealing Components, Empa, Ueberlandstrasse 129, CH-8600 Duebendorf, Switzerland
4) Center for X-ray Analytics, Empa, Ueberlandstrasse 129, CH-8600 Duebendorf, Switzerland
5) Lucerne University of Applied Sciences and Arts, Technikumstrasse 21, CH-6048 Horw, Switzerland
Abstract
Experimental setup
References
Foamed bitumen allows mixing and compacting warm asphalt at lower
temperatures, therefore reducing energy consumption and costs [1]. By
mixing a small quantity of water, typically 1- 6.0 w-%, with hot bitumen,
a foam is formed, which has, at a given temperature, better wetting and
coating capabilities than bitumen alone [1]. The amount of water, the
bitumen temperature and additives influence the structure and dynamics
of foamed bitumen, which determines its properties, like expansion ratio
and half-life time [2, 3].
Fast X-ray computed tomography (4 s per 3D CT) allows investigating
the time-resolved morphology of foamed bitumen if a stabilizer* is added
to slow down the collapse of the foam. * TEGO Addibit FS 725 A, EVONIK, Switzerland
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1) X-ray flat panel detector (Perkin Elmer, XRD 1621 CN3 ES)
2) Rotation table (Micos, UPR-160 F air) 3) XYZ stages (Micos, LS-270)
4) X-ray microfocus tube (XT9160-TXD) 5) Bitumen supply hose
6) Plexiglas cylinder with bitumen foam (Ø 104 mm)
Image analysis
Conclusion
Reconstruction method
By means of a fibre reinforced plastic hose, 180° hot foamed bitumen was
injected into a Plexiglas cylinder mounted on the rotation table of the X-
ray system. The microfocus X-ray source was operated at 80 kV
acceleration voltage and 300 µA (i.e. 24 W). The X-ray detector was read
out with ~14.5 frames/s. The rotation speed was between 90 °/s.
No filter Mean filter
(radius 3), final choice
Median filter Non-local means
filter [5] Gauss filter
Mean filter
(radius 5)
The three-dimensional shape of the foamed bitumen was calculated from
59 projection images acquired over 360° by a Feldkamp algorithm [3].
Because of the low SNR of the projection images, different filters were
applied on the projection images prior to the reconstruction:
[1] J. W. Button, C. Estakhri, and A. Wimsatt, System 7, 94 (2007).
[2] M. F. Saleh, Int. J. Pavement Eng. 8, 99 (2007).
[3] B. W. Hailesilassie, P. Schuetz, I. Jerjen, M. Hugener, and M. N. Partl,
J. Mater. Sci. 50, 79 (2014).
[4] L. A. Feldkamp, L. C. Davis, and J. W. Kress, J. Opt. Soc. Am. A 1, 612 (1984).
[5] http://www.ipol.im/pub/art/2011/bcm_nlm/
[6] http://fiji.sc/Fiji
[7] https://en.wikipedia.org/wiki/STL_(file_format)
[8] http://www.volumegraphics.com/products/vgstudio-max/basic-functionality/
[9] http://www.gom.com/de/3d-software/gom-inspect.html
Even a low power (24 W) microfocus X-ray tube allows obtaining
reasonable fast (4s) 3D CT measurements for visualizing the time-
evolution of foamed bitumen:
• The use of a high power X-ray source would improve the SNR and
spatial resolution considerably.
• A faster X-ray detector would help to reduce motion artefacts.
• Optimized noise filters may improve the results.
• A gantry CT scanner would eliminate the centrifugal force artefacts.
The 3D CT data was inverted and filtered with a Gaussian blur filter
(radius 4) using the freeware Fiji [6], then the bubbles were segmented
and the surface data saved in STL file format [7] using a trial version of
VGStudio MAX [8]. The final visualization was done with the GOM
Inspect freeware [9].
Results
t = 0 s
Result not reliable due to
motion artefacts!
Nevertheless, bubbles
are fairly flat and have a
preferential direction,
probably due to the
initial spraying.
t = 14 s
Bubbles as small as
~0.5 mm3 can be seen.
The bitumen cooled
down a bit and is
therefore less viscous:
The shape of the
bubbles becomes
spherical.
t = 34 s
The bitumen collapsed
considerably and the
surface approaches the
ROI. The CT data
indicates that the
bitumen is less dense
close to the surface.