## 4 Materials and Methods
End-to-end ultrasonic examination of centrifuged concrete was carried out using a meter of time and velocity of the propagation of ultrasound waves, \"Pulsar-2.2\", designed to assess the strength, density and modulus of elasticity of properties and defectoscopy of building materials in time, propagation velocity and shape of ultrasonic pulses. The measurements were carried out in accordance with Russian GOST 17624-2012. The setup during end-to-end ultrasound examination and a general view of test samples are shown in Figure 1. The technical characteristics of the device \"Pulsar 2.2\" are presented in Table 1.  
The adopted instrumental methods for investigating concrete prototypes and the used instruments and equipment [43; 44; 45; 46; 47; 48; 49] made it possible to assess the picture of the real variatropy of the structure and conclude that the accepted direction of research is correct. In total, 9 vibrated, centrifuged and vibro-centrifuged samples of annular cross-section were manufactured and tested (Figure 2), each with an outer diameter \(D\) = 450 mm; an inner hole diameter \(d\) = 150 mm and a total height \(H\) = 1200 mm. In the experiments, the manufacturing technology was varied. The following conventions for the manufacturing technology were adopted using the following sample codes:  
V--vibration,  
C--centrifugation,  
VC--vibro-centrifugation. \begin{table}
\begin{tabular}{c l c c} \hline \hline
**No.** & **Indicator Name** & **Units** & **Indicator** \\ \hline
1 & Measurement range of the propagation velocity of ultrasonic waves & m/s & 1000–10,000 \\ \hline
2 & Measurement range of the propagation time of ultrasonic waves & \(\mu\)s & 10–100 \\ \hline
3 & Measurement base for surface end-to-end ultrasound examination & mm & \(120\pm 1\) \\ \hline
4 & Power consumption, no more than & W & 0.7 \\ \hline
5 & Weight of the device with a complete set, no more than & kg & 1.5 \\ \hline
6 & Overall dimensions & & \\  & (length \(\times\) width \(\times\) height): & & \\  & (i) electronic unit & mm\({}^{3}\) & \(205\times 115\times 35\) \\  & (ii) surface ultrasound probe & mm\({}^{3}\) & \(250\times 50\times 100\) \\  & (iii) transducer of end-to-end ultrasound examination & mm\({}^{2}\) & \(\varOmega 36\times 62\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Technical characteristics of device “Pulsar 2.2”. Figure 1: (**a**) Setup during end-to-end ultrasound examination, and (**b**) general view of test samples. The problem of assessing the influence of manufacturing technology (vibration, centrifugation, vibration centrifugation) on the integral (common, averaged over the cross-section) and differential (differing in the layers of the cross-section) characteristics of concrete was investigated:  
1. Density \(\rho\);
2. Axial compression strength (cubic \(R_{b,cub}\) and prismatic \(R_{b}\));
3. Limiting strains during axial compression \(\varepsilon_{b}\);
4. Axial tensile \(R_{bt}\) and flexural tensile strength \(R_{btb,i}\);
5. Limiting strains during axial tension \(\varepsilon_{bt}\);
6. Elastic modulus (in compression \(E_{b}\) and tension \(E_{bt}\));
7. Diagram \"stress \(\sigma_{b}\)-strain \(\varepsilon_{b}\)\" in compression;
8. Diagram \"stress \(\sigma_{bt}\)-strain \(\varepsilon_{bt}\)\" in tension. In the experiment, the following data were taken for aggregates:  
1. Granite crushed stone of the JSC \"Pavlovsk Nerud\" (Russia) with a fraction of 5-20 mm;
2. Quartz sand of the Grushevsky deposit (Russia), \(\rm M_{k}=2.0\). Figure 3 shows a scheme for obtaining small-sized concrete samples for testing.