Fig. 2: 3D rendering of the XCT images and isolated cracks of the brittle and semi-ductile specimens.

Middle column shows vertical sections of the samples while left and right column show radial cross-section taken in places indicated in red and yellow. The blue boxes represent the sub-volumes in which permeability, crack length and aperture was computed and the numbers labeled are linked to the results presented in Table 1. The bottom inset show the x, y and z coordinates used in the later calculations. Note that z is parallel to the applied deviatoric stress.