## 1 Introduction
According to their results, at the end of freezing-thawing test, the sample experienced considerable changes in its BTS due to the adverse effects of the freezing-thawing process. Overall, the findings of previous studies have shown that the BTS of stones decreases from low to high degrees, due to the harmful effects of deterioration processes. Generally, a stone with higher BTS exhibits better durability behavior against deterioration processes [16; 17; 18; 19]. Therefore, the BTS can be a good indicator for evaluating the durability of stone subjected to deterioration processes. For the strength characteristics of stones, including the uniaxial compressive strength (UCS) and point load index (PLI), several classifications have been proposed by people and institutions. In all these classifications, stones were categorized into several strength classes based on their UCS and PLI values. However, there is no classification for stone BTS in the literature, and this is a critical gap in the previous studies. On the other hand, BTS is an important parameter in assessing the durability of stone, especially in situations where the stone is under tensile stresses caused by some deterioration processes, such as freezing-thawing, salt crystallization, heating-cooling, and wetting-drying. It is evident that under conditions where the stresses governing the stone are predominately tensile, the tensile strength rather than compressive strength can provide a better assessment of the durability behavior of the stone. This can be one of the main reasons why researchers in \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Source**} & \multirow{2}{*}{**Stone Type**} & \multicolumn{4}{c}{**Deterioration Process Type**} & \multirow{2}{*}{**BTS Changes**} \\ \cline{3-3} \cline{5-6}  & & **FT** & **SC** & **HC** & **WD** \\ \hline \multirow{2}{*}{[PERSON] and [PERSON] [1]} & Andesitic & \(\times\) & & & & Decreasing \\  & Ignimbrite & \(\times\) & & & & Decreasing \\  & [PERSON] et al. [7] & Limestone & \(\times\) & \(\times\) & \(\times\) & & Decreasing \\  & [PERSON] et al. [20] & Sandstone & & & & \(\times\) & Decreasing \\  & [PERSON] et al. [21] & Limestone & & & & \(\times\) & Decreasing \\  & [PERSON] and [PERSON] [22] & Marble & \(\times\) & & \(\times\) & & Decreasing \\  & [PERSON] et al. [23] & Different stone types & & \(\times\) & & & Decreasing \\ [PERSON] and [PERSON] [24] & Limestone & \(\times\) & & & & Decreasing \\  & [PERSON] et al. [25] & Granite & \(\times\) & \(\times\) & \(\times\) & & Decreasing \\  & [PERSON] et al. [11] & Tuff & \(\times\) & & & & Decreasing \\  & [PERSON] et al. [16] & Limestone & \(\times\) & \(\times\) & & & Decreasing \\  & Sedimentary stone & & & & & \(\times\) & Decreasing \\  & types & & & & & & Decreasing \\  & [PERSON] et al. [27] & Sandstone & \(\times\) & & & & Decreasing \\  & [PERSON] et al. [28] & Travertine & & \(\times\) & & & Decreasing \\  & [PERSON] et al. [29] & Sandstone & & & & & Decreasing \\  & [PERSON] and [PERSON] [30] & Schist & \(\times\) & & & & Decreasing \\  & [PERSON] [31] & Limestone & \(\times\) & \(\times\) & \(\times\) & \(\times\) & Decreasing \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Some previous studies on the BTS of stones subjected to deterioration processes. previous studies have not employed compressive strength classifications, e.g., UCS and PLI classifications, to assess the durability of stone. The aim of the present study is to provide a quantitative-qualitative classification of igneous building stones based on their BTS so that it can be used as a suitable and practical tool for a quick evaluation of stone durability against deterioration processes under laboratory conditions.