## 3 Results and Discussion
### Discussion  
The essence of sulfate attack is that the hydroxide and calcium hydroaluminate contained in concrete enter into a chemical reaction with sulfate ions to form gypsum and calcium hydroaluminate. The reaction products are deposited on the walls of the pores and \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Sulfate Attack Index**} & \multicolumn{3}{c}{**Concrete Type**} \\ \cline{2-4}  & **Vibration** & **Centrifugation** & **Vibrocentrifugation** \\ \hline Sulfateattackrate\(\left(\frac{\text{mgCaO}}{\text{cm}^{2}\text{days}}\right)\) & 7.1 & 6.0 & 5.2 \\ \hline Depth of destruction of concrete (mm) & 3.21 & 2.07 & 1.11 \\ \hline \hline \end{tabular}
\end{table} 
Table 11: Indicators of sulfate attack. Figure 12: Samples of vibrocentrifuged concrete after cyclic sulfate attack at 8\(\times\) magnification: (a) after 30 cycles; (b) after 60 cycles. partially clog them. Further, if highly soluble alkalis are not formed in the reaction zone, the pH will gradually decrease with an increase in the acidity of the pore fluid, which in turn leads to the hydrolysis of first high-aluminate and gradually low-aluminate calcium hydrosilicates included in the framework of the concrete matrix. The gradual destruction of the concrete structure leads to the loss of its strength [60]. In general, the results obtained in this study are in good agreement with a number of other studies that also studied the effect of sulfate attack on the physical and mechanical properties of various types of concrete [2; 3; 4; 5; 6; 12; 13; 14; 16; 17; 18; 19; 20; 21]. As the main positions for comparing the obtained results with the results of other authors, we can single out the loss of strength characteristics and mass. A trend similar to this study for a decrease in strength characteristics and a decrease in weight with an increase in the number of sulfate attack cycles is observed in [2; 4; 16]. But unlike [2], where the strength properties of concrete after 10-15 cycles of sulfate attack slightly increased, in the current study, the strength properties from the first cycle of sulfate attack do not exceed the control values, and only decrease with an increase in the number of cycles. With regard to the determination of the resistance of concrete in an acid solution, [8] can be considered similar in terms of the acid environment used. The sulfate attack mode chosen in this study coincided with the drying conditions but differed in the duration of the \"dry-wet\" cycles from [61]. So, the scientific novelty of the study can be considered the first created data system for three technologies, namely vibrating, centrifuging, and vibrocentrifuging of concrete, depending on sulfate attack. In view of the fact that all methods of protection against sulfate attack can be divided into two groups, namely the prescription and technological ones, we will evaluate the achievements of each of these methods separately. Laboratory experimental results have shown that vibrocentrifuged concrete has the highest degree of resistance to sulfate attack, and centrifuged concrete has a slightly lower resistance, while traditional vibrated non-variotropic concrete has the lowest resistance. Such differences and advantages of some technologies over others are due to differences in the structure of the concrete itself. The phenomenon of variotropy thus creates additional protection and the effect of protection from sulfate attack for concretes used in structures with increased responsibility. These conditions include a wide range of operating conditions. Thus, the stability of variotropic vibrocentrifuged concretes of reinforced concrete structures of critical facilities will be ensured only by a technological solution that occurs during the regrouping of centrifugation technology to vibrocentrifugation. This is a technologically simple way; however, the result of such an intervention in technology is very high, and therefore, the technological advantages of vibrocentrifuged concretes are proved, as in previous articles [34; 41].