# Influence of Variotropy on the Change in Concrete Strength under the Impact of Wet-Dry Cycles
## 3 Results
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Type of Concrete**} & \multicolumn{10}{c}{**Number of Wetting and Drying Cycles**} \\ \cline{2-13}  & **0** & **50** & **100** & **150** & **200** & **250** & **300** & **350** & **400** & **450** & **500** & **550** & **600** \\ \hline \multirow{4}{*}{Vibrated} & \multirow{4}{*}{0} & \multirow{4}{*}{1} & \multirow{4}{*}{3} & \multirow{4}{*}{6} & \multirow{4}{*}{10} & \multirow{4}{*}{9} & \multirow{4}{*}{4} & \(\Delta R_{b,cub}\), \% & & & & & \\ \cline{2-13}  & & & & & & & & & & & & & \\ \cline{2-13}  & & & & & & & & & & & & & \\ \cline{2-13}  & 0 & 2 & 4 & 5 & 7 & 6 & 2 & 1 & –7 & –11 & –14 & –19 & –22 \\ \hline \multirow{4}{*}{Centrifuged} & \multirow{4}{*}{0} & \multirow{4}{*}{2} & \multirow{4}{*}{5} & \multirow{4}{*}{8} & \multirow{4}{*}{11} & \multirow{4}{*}{8} & \multirow{4}{*}{5} & \multirow{4}{*}{1} & \multirow{4}{*}{–4} & \multirow{4}{*}{–9} & \multirow{4}{*}{–11} & \multirow{4}{*}{–15} & \multirow{4}{*}{–18} \\ \cline{2-13}  & & & & & & & & & & & & & \\ \cline{2-13}  & & & & & & & & & & & & \\ \hline \multirow{4}{*}{Vibrocentrifuged} & \multirow{4}{*}{0} & \multirow{4}{*}{4} & \multirow{4}{*}{7} & \multirow{4}{*}{11} & \multirow{4}{*}{12} & \multirow{4}{*}{9} & \multirow{4}{*}{6} & \multirow{4}{*}{2} & \multirow{4}{*}{–2} & \multirow{4}{*}{–6} & \multirow{4}{*}{–10} & \multirow{4}{*}{–13} & \multirow{4}{*}{–15} & \multirow{4}{*}{–15} \\ \cline{2-13}  & & & & & & & & & & & & & \\ \cline{2-13}  & & & & & & & & & & & & & \\ \hline \multirow{4}{*}{Vibrocentrifuged} & \multirow{4}{*}{0} & \multirow{4}{*}{5} & \multirow{4}{*}{8} & \multirow{4}{*}{10} & \multirow{4}{*}{14} & \multirow{4}{*}{8} & \multirow{4}{*}{5} & \multirow{4}{*}{3} & \multirow{4}{*}{–2} & \multirow{4}{*}{–7} & \multirow{4}{*}{–9} & \multirow{4}{*}{–12} & \multirow{4}{*}{–14} \\ \cline{2-13}  & & & & & & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Change in the strength characteristics of vibrated, centrifuged, and vibrocentrifuged concretes after cyclic wetting and drying at pH 10.  
concretes was 22%, for centrifuged, 18%, and for vibocentrifuged, 14%. The smallest losses in the strength characteristics of concretes made using three technologies are observed in vibrocentrifuged concrete in comparison with centrifuged (4%) and vibrated (8%). After analyzing the results obtained, it can be concluded that concretes made using various technologies, when moistened in aqueous solutions with pH 7 and pH 10, have similar trends in cubic and prism compressive strengths. In all cases, the maximum strength values were recorded after 200 cycles of wetting and drying, and starting from the 250 th cycle, a drop in strength was observed. As for concrete samples subjected to saturation in an aqueous medium with pH 5, the nature of the change in strength characteristics is different here. The drop in strength for vibrated, centrifuged, and vibrocentrifuged concretes was recorded after the first 50 cycles of wetting and drying and continues further. When concrete is wetted in an aggressive environment with pH 5, the effect favorable for strength described above, observed up to 200 cycles at pH 7 and pH 10, is neutralized by the degree of aggressiveness of the environment and the corresponding destructive processes occurring in the structure of the concrete due to its impact. At the same time, different water-cement ratios are due to differences in the technology of molding and compacting the concrete mixture. For vibrated--this is a vibration seal for centrifuged and vibrocentrifuged--this is a centrifugal seal. At the same time, one of the main criteria for comparing concrete mixtures obtained using different technologies was the indicator of the workability of the mixture. For all mixtures, it was the same (grade for workability P1, that is, the draft of a standard cone was not less than 1 and not more than 4 cm) [56].