micro-XRCT data set (projection and reconstructed images) of a Carrara marble core with a diameter of 5 mm. The sample was extracted with a water-cooled diamond drill from a bigger sample with a diameter of 30 mm and a length of 80 mm, which was previously subjected to the following thermal treatment to initiate cracks: Starting at room temperature (20°C), the sample was heated up at a rate of 3 K/min to 500°C. After a holding time of 2 hours at this temperature, the sample was subsequently quenched in water at room temperature (20°C).

Additionally, a segmentation result, into solid and crack regions, is provided using the U-Net model based on the code provided by Lee et al. (2021, 2022). Note that the segmentation result significantly overestimates the crack volume as described and discussed in detail in Lee et al. (2022) and Ruf et al. (2025). A way to tackle this problem is shown in the related publication Ruf et al. (2025).