## 4 Results and Discussion  
Visual observations after the four-season simulation in the FITOCLIMA climatic chamber showed no changes in appearance regarding any discoloration due to oxidation of metallic minerals and inclusions. The physical and mechanical properties before and after the aging are listed in Table 3. As introduced in the above sections, the subarctic Dfc climate can cause deep damage in most artificial and natural materials including natural stones. According to the decay diagram [54] and based on the mean annual precipitation (2085 mm) and temperature (0.2 \({}^{\circ}\)C), the weathering conditions on geomaterials of Dfc Alpine sectors are not specified. However, the chemical decay (e.g., dissolution, hydration, hydrolysis oxidation, and reduction) and the biological decay (e.g., wedge work of roots and burrowing and boring of animals) is lower at average annual temperatures around zero or less, and in fact in this research no chemical degradation was detected. Conversely, physical decay, in particular the frost action, was naturally higher. The effects of freeze-thaw action are linked to pore space and pore size distribution in stones (open porosity of \(>\)5%). However, damage is also reported in low-porosity stone materials such as marbles, granites, and slates. In these stones, damage can be related to other textural features (besides the characteristics of the pore space) such as the presence of slaty cleavage planes, veins, or stylolites [55]. A similar type of damage was recorded in this study's aging cycles, as the crystallization of water inside the slate caused major longitudinal fractures, S1 parallel to S0 slaty cleavage planes, visible in Figure 5. These fractures have openings varying between 50 and 150 \(\upmu\)m with irregular spacing in the order of 5 cm (Figure 6a,c). Moreover, principles of exfoliation and spalling are present in the samples following exposure to seasonal cycles (Figure 6b,d). From Table 3, it is seen that the volumetric expansion caused an increase in the porosity of the slate from a pre-aging value of 0.87 \(\pm\) 0.1 to 1.5 \(\pm\) 0.2%, indicating an increase of 72%. Similarly to the information reported [56], this change in porosity was caused by microfissures, some small amounts of debris, and some slaty cleavage planes' partial and total detachment. An irrelevant change in the apparent density was detected (\(-\)0.7%), shifting from 2833.5 \(\pm\) 6.5 kg/m\({}^{3}\) to a final value of 2813.4 \(\pm\) 3.8 kg/m\({}^{3}\), as shown in Table 3. The increase in the porosity due to the opening of the fracturing planes causes a lower speed of propagation of the compressional P-wave. The initial value of 6120 \(\pm\) 410 m/s was reduced by approximately 9 %, to 5566 \(\pm\) 146 m/s. Following the aging test, the values of VRI (Velocity Ratio Quality Index) [57] were assessed as 0.91 \(<\) VRI \(<\) 0.97. This parameter \begin{table}
\begin{tabular}{l l l l l} \hline \hline \multirow{2}{*}{**Physical and Mechanical Properties**} & **No. of Tested** & **Before** & **After** & **Relative** \\  & **Specimens** & **Aging** & **Aging** & **Difference (\%)** \\ \hline Uniaxial compressive strength & & & & \\ (MPa) & 10 & 175 \(\pm\) 13 & 133 \(\pm\) 14 & \(-\)24 \\ \hline Flexural strength under concentrated & & & & \\ load (MPa) & 10 & 30.4 \(\pm\) 9.2 & 14.9 \(\pm\) 3.8 & \(-\)50.9 \\ \hline Anchor rupture load & & & & \\ (N) & 12 \(\times\) 4 & 3141 \(\pm\) 221 & 2420 \(\pm\) 275 & \(-\)22.9 \\ \hline Point load strength index & & & & \\ (MPa) & 10 & 13.1 \(\pm\) 3.1 & 12.5 \(\pm\) 2.4 & \(-\)4.5 \\ \hline P-wave ultrasound speed & & & & \\ (m/s) & 10 & 6120 \(\pm\) 410 & 5566 \(\pm\) 146 & \(-\)9 \\ \hline Young’s modulus & & & & \\ (GPa) & 10 & 88.5 \(\pm\) 13.1 & 72.3 \(\pm\) 6.9 & \(-\)18.3 \\ \hline Apparent density & & & & \\ (kg/m\({}^{3}\)) & 6 & 2833.5 \(\pm\) 6.5 & 2813.4 \(\pm\) 3.8 & \(-\)0.7 \\ \hline Open porosity & & & & \\ (\%) & 6 & 0.87 \(\pm\) 0.1 & 1.5 \(\pm\) 0.2 & 72 \\ \hline \hline \end{tabular}
\end{table}