## 2 Materials and Methods  
### Experimental Part  
The influence of F/T action on the wall as a composite was studied by experiments presented in [9]. Here, only basic information on the experiment is provided, and detailed description is given elsewhere [9]. Two different types of mortar were used for the construction of wallets exposed to 50 and 150 F/T cycles: mortar M1 made from lime putty and mortar M3a, where 40% (by mass) of ground granulated blastfurnace slag was added according to the share of dry binder in lime putty. In both cases, a volumetric ratio lime putty:sand of 1:3 was taken into account. Although the hardening processes of the two used mortars differ, they are both relatively long lasting and are described in more detail for a better understanding of the experimental results. Mortar M1 gains its strength solely because of carbonation, while for mortar M3a, two processes are responsible for gaining strength: pozzolanic reaction and hydration. Slag, the use of which is growing increasingly in the restoration of architectural heritage, is a latent hydraulic binder (it possesses hydraulic properties when properly activated) and is not the classic pozzolan, although it has similar properties to pozzolan [12]. Basically, slag is a waste material, obtained as a byproduct in the production of iron. When granulated blast furnace slag is mixed with water, its initial rate of hydration is much lower than when the water is mixed with Portland cement. With the addition of alkali, Portland cement, or lime, the reaction accelerates (slag is activated). The products of the setting of the lime and lime slag mixture are calcium silicate hydrates (CSH phase) [13]. Although lime-pozzolana mortar's pozzolanic reaction takes place first and carbonation represents a complementary reaction, the subsequent rate and sequence of pozzolanic reaction and carbonation depends on the composition of the binder, pozzolanic reactivity, and curing conditions. Curing in moist conditions enables faster progression of the pozzolanic reaction, while curing under dry conditions improves the rate of carbonation. The degree of pozzolanic reaction is also affected by the carbonation, which consumes part of the lime and can thus influence the mechanical properties and the porosity of lime-pozzolana mortars [14]. Lime-cement mortars setting is a combination of hydration of cement and carbonation of lime. Hydration of cement always takes place before carbonation of lime and the degree of both depends on the curing conditions. The rate of cement hydration is increased by curing in moist conditions, while combined wet/dry curing conditions increases the level of lime carbonation. In comparison with reference cement mortars, lime-cement mortars exhibit higher porosity, lower compressive strength, and more ductile behavior [15]. Carbonation takes place even in two-year-old specimens [16]. The hardening process of lime-pozzolana mortars is also long [17; 18]. Conditions in a climatic chamber have a favorable effect on both processes (wetting of specimens, air circulation, relative humidity between 40% and 60%). Since the overall porosity is reduced by the carbonation, measurements of the ultrasonic transition time can be used to evaluate its progression [19]. Measurements of the ultrasonic velocities (UVs) on mortar prisms M1 have shown that on 347-day-old specimens, the UVs were 8% higher compared to 181-day-old specimens, which shows that carbonation was still ongoing. For mortar prisms M3a, the UVs measured in the longitudinal direction on 346-day-old specimens compared to 185-day-old specimens remained approximately the same, but there was a reduction of 24% in the transverse direction. Such a reduction could be the consequence of increased porosity or damage in the structure of mortar M3a [9].