## 3 The Santa Pudia (SP) Stone
#### Freeze-Thaw Cycles for Different RHs  
According to [27], given the size of its pores and the high degree of interconnection between them, Santa Pudia stone is very susceptible to damage by freeze-thaw cycles. In [27], SP calcarenite specimens were tested under freeze-thaw cycles, in accordance with EN 12371 [36], to assess their behavior and frost resistance. In this test, before being frozen in air for six hours, the samples must first be dried and then submerged in water until fully saturated. After freezing, the samples are kept in water for a specified period.  
In the present study, to quantify the influence of saturation degree on the deterioration of SP calcarenite, specimens with different water contents were tested under freeze-thaw cycles for up to 50 cycles. The three water contents considered were 0%, 50%, and 100%. A total of nine specimens, each measuring 120 \(\times\) 120 \(\times\) 50 mm, were tested (three specimens for each water content). Full saturation was achieved by submerging the specimens in water for 24 h. The average amount of water required for full saturation of the three specimens was used as a reference for 50% saturation. Each specimen was placed in a hermetically sealed plastic bag to maintain constant humidity, and each specimen was subjected to temperatures ranging from \(-\)20 \({}^{\circ}\)C to 15 \({}^{\circ}\)C in each cycle, which reasonably aligns with the daily temperature variation in the Granada province.  
Each cycle consisted of 24 h freezing and thawing periods. Each sample was hermetically sealed throughout the experiment and only removed from the bags for weighing. The weight of each specimen was recorded every five cycles, and the results are summarized in Figure 2. Regardless of water content, as the tests progressed, the specimens experienced material loss around the perimeter, with pits or small holes appearing on the surface.  
As shown in Figure 2, the number of freeze-thaw cycles and the water content significantly influence the deterioration of SP calcarenite, with freeze-thaw damage increasing as the water content rises [37]. However, the level of deterioration was not as severe as that observed by [27] using the EN 12371 [36] test, possibly due to the size effect and differences in the freeze-thaw procedure described above.  
For the samples tested (with dimensions: 120 \(\times\) 120 \(\times\) 50 mm), a uniform recession R (in mm) can be estimated as follows:  
\[\begin{array}{l}\frac{\mathrm{V}_{\mathrm{ins}}}{\mathrm{V}_{\mathrm{ini}}}= \frac{\mathrm{A}\mathrm{W}}{\mathrm{V}_{\mathrm{ini}}}\simeq\frac{2.120\cdot 1 20\cdot 8+4\cdot 120\cdot 50\cdot 8}{120\cdot 120\cdot 50}=(2/50+4/120)\mathrm{R}\ \rightarrow\\ \mathrm{R}\simeq\frac{2}{7/50+4/120}\frac{\mathrm{A}\mathrm{W}}{\mathrm{V}_{ \mathrm{ini}}}=13.6\frac{\mathrm{A}\mathrm{W}}{\mathrm{V}_{\mathrm{ini}}}\ \rightarrow\ \mathrm{R}\simeq 0.136\mathrm{A}\mathrm{W}\ [\%]\end{array} \tag{1}\]  
where \(\mathrm{V}_{\mathrm{ini}}\) is the initial volume of the sample and \(\mathrm{V}_{\mathrm{loss}}\) is the volume lost during the freeze-thaw test (\(\mathrm{W}_{\mathrm{ini}}\) and \(\mathrm{A}\mathrm{W}\) represent initial weight and weight variation, respectively).  
In the next section, deterioration patterns based on observations from various heritage buildings are derived. These data are used to construct a recession diagram. Although laboratory data are not required for the development of the diagram, these data are included to demonstrate that they become redundant when sufficient field data are available.