## 2 Materials and Methods
### Methods
The production and testing of samples in the laboratory were carried out in a room with an air temperature of 20 \(\pm\) 2 \({}^{\circ}\)C and relative humidity of 60 \(\pm\) 5%. The parameters of the vibrating platform (Figure 1a) are presented in Table 5.  
A device for the manufacture of products from centrifuged/vibrocentrifuged concrete containing a frame on which drive and support shafts, support rollers, shape, an electric motor with a coupling, and a thyristor control unit are mounted additionally contains steel ribs on the support and drive shafts (Figure 1c). The device consists of a frame 1, on which two shafts are mounted: drive 2 and support 3. The drive includes a multispeed electric  
Figure 1: Equipment for molding and compaction of samples: (**a**) laboratory vibrating platform for the manufacture of vibrated concrete samples; (**b**) photo and (**c**) drawing of a device for manufacturing samples of ring cross-section from centrifuged/vibrocentrifuged concrete. \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline Carrying capacity, up (kg) & 100 \\ \hline The frequency of oscillations (oscillations in min) & 2900 \(\pm\) 100 \\ \hline Amplitude of oscillations (mm) & from 0.30 to 0.55 \\ \hline Vibrator (type) & IV-99B \\ \(-\) Power (KW) & 0.5 \\ \(-\) Work voltage (V) & 380 \\ \(-\) Current frequency (Hz) & 50 \\ \hline Installation of forms on the table & Mechanical clamping bar \\ \hline The overall dimensions of the vibration platform (mm) & \\ \(-\) Length, no more & 580 \\ \(-\) Width, no more & 400 \\ \(-\) Height, no more & 580 \\ \hline Weight, no more (kg) & 60 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Technical characteristics of the laboratory vibration platform. motor 4 of a DC with a smooth adjustment of the thyristor control unit 8. A stop with supporting bearings 5 is supportive and can be adjusted depending on the diameter of form 6. The shafts of the drive 2 and the support 3 are made with the application of steel ribs 11, which provide high-frequency vibrations when moving the shape. The smoothness of the launch provides a clutch 7. The drive 2 and the support 3 shafts through the stops with the supporting bearings 5 are attached to the frame 1 using bolts 9 with a diameter of 12 mm. This device works as follows: on drive 2 and support shafts 3, a steel form of a given standard size 6 is installed; then there is a rotational movement from the electric motor 4 of DC with a thyristor control unit 2. Driving 2 and support 3 shafts through stops 5 are transmitted through the coupling 7 fixed to the frame 1 using bolts 9 with a diameter of 12 mm. Acceleration and smooth control of rotation speed are carried out due to the thyristor control unit 8, which allows one to change the speed of the engine of 4 DC. The rotation from the drive shaft 2 steel form 6 is transmitted due to friction forces. The steel form 6 has supports 10. The seal in steel form 6 occurs due to the action of the centrifugal sealing force on the components of the concrete mixture and high-frequency vibrational oscillation, which create steel ribs 11 on the drive 2 and the support of 3 shafts. The study of the physical and mechanical characteristics of concrete during cyclic sulfate attack in the \"dry-wet\" states included the following steps:  
* One cycle of sulfate attack lasted three days. Within 1 day, concrete samples were moistened in a 5% Na\({}_{2}\)SO\({}_{4}\) solution (pH equal to 6 \(\pm\) 0.1) (Figure 2), and then the samples were removed from the solution and kept for 2 days in an air environment at a temperature of 25 \({}^{\circ}\)C in a ventilated room. * The test for cyclic sulfate attack was carried out for 180 days. After 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, and 60 cycles, the compressive strength was determined for cubic and prismatic samples, as was the weight loss of experimental samples.