# Influence of Variotropy on the Change in Concrete Strength under the Impact of Wet-Dry Cycles
## 2 Materials and Methods
### Methods  
Portland cement tests were carried out according to the GOST 30744 \"CEMENTS. Methods of testing with using poly fraction standard sand\" [48]. The sand was tested according to GOST 8735 \"Sand for construction work. Testing methods\" [49], crushed stone according to GOST 8269.0 \"Mountainous rock road-metal and gravel, industrial waste products for construction works methods of physical and mechanical tests\" [50]. The samples of the concrete mixture were made according to three technologies: vibrating, centrifuging, and vibocentrifuging. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline  & \multicolumn{6}{c}{Physical and mechanical properties} \\ \hline Compressive strength at the age of & Start setting & Uniformity of volume change & Grinding fineness (residue on 2 days (28 days) (MPa) & Start setting (minutes) & Uniformity of volume change (expansion) (mm) & Grinding fineness (residue on 2 days) (mm) & Grinding fineness (residue on 2 days) & Grinding fineness (residue on 2 days) & Grinding fineness (residue on 2 days) & Grinding fineness (residue on 2 days) & Grinding fineness (residue on 2 days) \\ \hline  & 18.9 (50.4) & & 135 & 1 & & 3.6 & \\ \hline \multicolumn{6}{c}{Chemical composition (\%)} \\ \hline SiO\({}_{2}\) & Al\({}_{2}\)O\({}_{3}\) & Fe\({}_{2}\)O\({}_{3}\) & MgO & CaO & SO\({}_{3}\) & TiO\({}_{3}\) & LOI & Na\({}_{2}\)O & K\({}_{2}\)O & Chlorine ion CI\({}^{-}\) \\ \hline
22.65 & 4.13 & 3.96 & 1.29 & 62.2 & 1.68 & 0.05 & 3.69 & 0.12 & 0.22 & 0.01 \\ \hline \multicolumn{6}{c}{Mineralogical composition (\%)} \\ \hline Tricalcium silicate & & Dicalcium silicate & Tricalcium aluminate & Tetracalcium aluminoiferrite & Tetracalcium aluminoiferrite \\ \hline
65 & & 17 & & 7 & & 11 \\ \hline \multicolumn{6}{c}{Crushed stone from sandstone with a fraction of 5–20 mm from the Potapov quarry (Azov-Dorskaya Non-Metallic Company JSC, Verkh nepotapov, Russia) was used as a coarse aggregate. The characteristics of the applied crushed stone are presented in Table 2.} \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Portland cement properties. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{\begin{tabular}{c} **Crushability,** \\ **(\%)** \\ \end{tabular} } & \begin{tabular}{c} **The Content of Lamellar** \\ **and Needle-Shaped** \\ **Grains, (\%)** \\ \end{tabular} & \begin{tabular}{c} **The Content of** \\ **Dust and Clay** \\ **Particles, (\%)** \\ \end{tabular} & \begin{tabular}{c} **Grain Content** \\ **of Weak Rocks,** \\ **(\%)** \\ \end{tabular} & \begin{tabular}{c} **Bulk Density** \\ **(kg/m\({}^{3}\))** \\ \end{tabular} & \
\begin{tabular}{c} **True** \\ **Density** \\ **(kg/m\({}^{3}\))** \\ \end{tabular} &
\begin{tabular}{c} **Frost** \\ **Resistance,** \\ **Cycles** \\ \end{tabular} \\ \hline
11.5 (type 1000) & 10.5 (group 2) & 0.5 & 2.1 & 1395 & 2658 & 200 (F200) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Physical and mechanical properties of crushed stone. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{\begin{tabular}{c} **Size Modulus,** \\ **M\({}_{\text{f}}\)** \\ \end{tabular} } & \begin{tabular}{c} **The Content of Dust** \\ **and Clay Particles, (\%)** \\ \end{tabular} & \begin{tabular}{c} **Clay Content in** \\ **Lumps, (\%)** \\ \end{tabular} & \begin{tabular}{c} **Sand Class According** \\ **to GOST 8736** \\ \end{tabular} & \
\begin{tabular}{c} **Bulk Density,** \\ **(kg/m\({}^{3}\))** \\ \end{tabular} &
\begin{tabular}{c} **True Density** \\ **(kg/m\({}^{3}\))** \\ \end{tabular} \\ \hline
2.1 (medium) & 1.6 & 0.12 & 1 & 1520 & 2603 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Physical properties of sand. The preparation of the concrete mixture using the vibrating technology was carried out in a laboratory concrete mixer BL-10 with the following order of loading the components: first water (W), then Portland cement (PC), then sand (S), and crushed stone (CrS).