Fig. 3: Comparison of phase-contrast synchrotron tomography and ptychographic X-ray computed tomography.
a Selected orthoslices at 19 h for (top) Syn-μCT [voxel size: 650 nm, total scanned volume: 5.25 108 μm3, overall acquisition time: 5 min], and (bottom) PXCT [voxel size: 186.64 nm, total scanned volume: 8.15 105 μm3, overall acquisition time: 3 h, 55 min]. b Enlarged views of the highlighted regions (purple squares) in a, in order to illustrate the level of detail that can be observed with these imaging modalities. Every voxel in Syn-μCT image starts to be evident. c Further enlarged views to illustrate the maximum level of detail that can be observed. (Top) The Syn-μCT image shows whitish particles (anhydrous cement particles) surrounded by hydrates (greyish voxels) which are highlighted by red arrows. (Bottom) The PXCT data, at the same magnification, shows a much higher level of detail. The C-S-H gel shells surrounding the alite particles are clearly visible (pink arrows). There is a water gap between the shell and the alite grain due to the inward dissolution of alite. Moreover, etch-pits on the surfaces of the alite particles are also visible (blue circles). The highest spatial resolution and better contrast of PXCT data allow visualizing submicrometre features of the dissolution-precipitation processes which are not visible in propagation-based Syn-μCT. Conversely, propagation-based Syn-μCT permits to scan much larger volumes in much smaller acquisition times, showing the complementary nature of both techniques.
