Fig. 6

A sample from brick A (top row) with 17.8% pores, 15.5% of them accessible to the surface (blue) with a surface/interior pore ratio of 6.7. Pores not accessible to the surface are in red. In the center images, surface-accessible pores are made partially transparent so interior ones are more visible; on the right, only the interior pores are shown (2.3%). The bottom row shows a sample from Brick F with 32.8% pores, 32.4% of which are accessible to the surface, leaving only 0.4 vol.% as interior pores inaccessible to the surface (surface/interior ratio of 81)