## 2 Materials and Methods
### Methods  
In the study, water activated with alkali and purified by a sorbent with different pH levels of an aqueous solution was used. Water activation was carried out by purification, which was filtered through sorbent-activated biochar from agricultural waste-rice straw. The technology for obtaining activated water was followed in strict accordance with the methodology [32]. For the manufacture of vibro-centrifuged samples, an experimental laboratory vibro-centrifuge was used. A schematic diagram of this installation and a detailed description are presented in [33]. Additionally, in [34; 35], the mode of forming prototypes of vibro-centrifuged concretes is described. The study used:  
* technological equipment--laboratory concrete mixer BL-10 (OOO \"ZZBO\", Russia, Chelyabinsk region, Zlatoust); laboratory vibrating platform SMZh-539-220A (OOO \"IMASH\", Armavir, Russia);
* testing equipment--hydraulic press IP-1000 (OOO NPK TEKHMASH, Neftekamsk, Republic of Bashkortostan, Russia), tensile testing machine R-50 (OOO IMash, Armavir, Russia);
* measuring instruments--stationary pH meter Starter 2100 (OHAUS CIS, Russia) measuring metal ruler 500 mm; laboratory scales; device for measuring deviations from the plane NPL-1; device for measuring deviations from perpendicularity NPR-1. The technological sequence of concrete mix molding was as follows. The original components are dosed and mixed in a concrete mixer. Then, reaching the required workability of the mixture with a cone draft of 1-4 cm, the mixture is placed in a particular mold located on a vibro-centrifuge. Finally, the drive is turned on and vibro-centrifugation is performed until the planned samples of the annular cross-section are obtained (according to the modes specified in [33]) for their further processing. In total, four basic samples of annular cross-section were manufactured and tested with the following dimensions:  
outer diameter D = 450 mm;  
inner diameter of the hole d = 150 mm;  
total height H = 1200 mm. The technique of making prototypes for determining the strength integral and differential characteristics of concrete is described [8]. The experimental research program is shown in Figure 1. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multicolumn{8}{c}{**Grain Composition**} \\ \hline \multicolumn{8}{c}{**Sieve Size, mm**} \\ \hline \multicolumn{8}{c}{**Retained**} & \multicolumn{2}{c}{**Retained and Cumulative Retained, \%**} & \multirow{2}{*}{**Passing**} & \multirow{2}{*}{**Fineness**} & \multirow{2}{*}{**Modulus**} & \multicolumn{2}{c}{**Content of Dust**} & \multirow{2}{*}{**True**} & \multirow{2}{*}{**Bulk Density,**} \\ \cline{1-1} \multicolumn{8}{c}{} & \multicolumn{4}{c}{**Through a Sieve No 0.16, wt. \%**} \\ \hline
**10** & **5** & **2.5** & **1.25** & **0.63** & **0.315** & **0.16** & & & \\ \hline
0 & 0 & 0.17 & 1.39 & 8.86 & 45.80 & 41.03 & 2.49 & & \\  & 0.17 & 1.56 & 10.42 & 56.21 & 97.25 & 99.74 & 1.66 & 1.1 & 2610 & 1438 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Physical characteristics of dense fine aggregate. Figure 1: Program of experimental research (sizes in mm). Measurements of the concrete strains of the test prisms were carried out by a chain of strain gauges with a side length of 50 mm and dial indicators with a graduation value of 0.001 mm. The strain measurement of a prism sample under axial compression is shown in Figure 1(a),b.  
Figure 2: Photo of strain measurement of the prism sample under axial compression (**a**); sample after collapse (**b**). with the requirements of GOST 24452 \"Concretes. Methods of prismatic, compressive strength, modulus of elasticity, and Poisson's ratio determination\" [37].