## 1 Introduction
The available standard test method to evaluate natural stone frost resistance is the EN 12371 (determination of frost resistance). According to this standard, specimens are subjected to controlled freezing and thawing conditions with temperatures ranging from \(-20\)\({}^{\circ}\)C to \(20\)\({}^{\circ}\)C and from \(14\) to \(168\) cycles according to the stone integrity. According to the EN 12371 standard, two options are available to evaluate frost resistance: (i) A technological test--in which frost resistance is assessed based on the mechanical performance changes in compression or flexural strength or anchorage rupture load, before and after the cycles. Figure 2: (a,c) Examples of slates used for roofing applications and associated damage due to snow accumulation; (b) damage due to frost action photo credits by [PERSON]. A visual inspection can also be included. (ii) An identification test--initial and periodic (after 14, 56, 84, 140, and 168 cycles, for example) visual inspection and dynamic Young's modulus assessment. There is also the option of apparent volume measurement comparison before and after the selected number of cycles. This standard has been commonly used by some authors [10; 11; 12; 13; 14; 15; 16; 17] who have detected a loss in weight due to decohesion and an overall reduction in mechanical properties (e.g., ultrasound wave velocity and uniaxial compressive strength). In our research, an innovative experimental climatic chamber setup was followed based upon EN 12371 standard principles on freeze-thaw, but with added parameters that are not included in this standard such as rain and temperature of a subpolar Dfc climate, aiming to artificially reproduce the four seasons in the climatic chamber. As far as the authors are aware, this is the first time the Dfc climate has been reproduced in the laboratory with the aim of foreseeing the behavior of natural stone in buildings in extreme weathering conditions. Moreover, this study includes the analysis of aesthetic parameters, in terms of color changes of the slate exposed to the Dfc climate solar radiation, by an aging test in a SOLARBOX climatic chamber. According to the statements of the quarrymen and traders of slate, its discoloration over time happens under solar radiation exposure. The aim of this study is to verify these statements. However, the process of natural stone discoloration when exposed to solar radiation is already known [18]. Dark-colored stones change to light shades while the latter change to dark shades following exposure [19]. Overall, natural stone color variation strictly depends on the color variation of the mineralogical phases comprising the stone, as further discussed in [20]. To realistically reproduce in the laboratory the climatic conditions of Dfc climate regions, the meteorological station data of Livigno, Italy (46\({}^{\circ}\)32\({}^{\prime}\)17.42\({}^{\prime\prime}\) N-10\({}^{\circ}\)08\({}^{\prime}\)09.57\({}^{\prime\prime}\) E, Z = 1826 m s.l.m.) were selected as an example in terms of air temperature and precipitation. To obtain reliable experimental data on natural stone aging under simulated conditions, seasonal cycles with a total duration of one month for each of the four seasons were programmed with temperatures and drying-wetting-frost conditions. Point load, compression/flexural strength, anchor rupture load, apparent density, and open porosity were evaluated before and after the complete sequence of winter, spring, summer, and autumn in the climate chamber. Aging tests on natural stones with realistic climatic conditions have already been carried out mimicking the Mediterranean Cas [19; 21; 22], the humid continental (Dfb), and the temperate oceanic (Cfb) [23] climates. All these studies aimed to investigate the suitability of artificial climatic conditions on reproducing a particular climate in the laboratory and to analyze the level of changes achieved in natural stone materials.