## 3 Results and Discussion  
We divided our research into seven stages. At the first, second, fourth, and fifth stages, a cylindrical mixer was used (Figure 2), while at the third, sixth, and seventh stages, a cylindrical mixer with a conical part was used (Figure 3). Mixer configurations used were as follows:  
Stage 1: D = 0.57 m, H = 1.15 m, with a downdraft turbine blade without baffles;  
Stage 2: D = 0.57 m, H = 1.15 m, with up-flow turbine impeller with baffles;  
Stage 3: D = 0.52 m, H = 0.78 m, V = 250 L, with baffles and replaceable tapered parts with different inclination angles;  
Stage 4: D = 0.19 m, H = 0.42 m, with a downdraft turbine impeller with baffles and a variable number of blades;  
Stage 5: D = 0.19 m, D = 0.57 m, D = 1.0 m, with different types of mixers with baffles;  
Stage 6: D = 0.52 m, H = 0.78 m V = 250 L, three-blade activator with replaceable blades;  
Stage 7: D = 0.52 m, H = 0.78 m, V = 250 L, with three plain blades with variable blade pitch. Effect of the Ratio of Mixture Height to Mixer Diameter on the Quality of Mixture and Power Consumption (Stage 1)  
In practice, the height of the foam concrete mixture in the mixer vessel (\(H_{mix}\)) (for blade mixers) is taken equal to the vessel diameter (\(D\)), that is, \(H_{mix}=D\). However, in the case of designing a mixer having another height of mixture in the vessel, the following question arises: Could this circumstance influence a homogeneity of the mixture density and a consumed power for mixing? Obviously, the parameter \(H_{mix}\)/\(D\) affects the density of a foam concrete mixture. Figure 4 shows the dependence of the homogeneity coefficient of the foam concrete mixture, as a function of the dependence of the density parameter \(K_{clm}\ =\ \overline{\rho}_{min}/\overline{\rho}_{max}\) on the ratio \(H_{mix}\)/\(D\). The experiment was carried out on a cylindrical mixer with a conical bottom. The density of the foam concrete mixture in the mixer was measured using the probes of mixture after its preparation. This operation was carried out through the discharge valves installed on the mixer body along the entire height with a step of 300 mm. Figure 4 shows that the homogeneity of the mixed mixture steadily decreased with an increase in the height of the mixture loading. This is explained by the fact that the circulation flow rate \(q\) decreased with an increase in the height of mixture, the movement of the mixture changed from a turbulent regime to a laminar one, and the turbulent transfer of the mixture particles between the central zone and the peripheral zone decreased. Then, an increase in the mixture height led to an increase in the  
Figure 4: Homogeneity of foam concrete mixture \(K_{clm}\) vs. ratio \(H_{mix}\)/\(D\) (experimental data). power consumption factor \(k_{N1}\) (subscript \(I\) defines the corresponding stage of the study), which was calculated at the \(I\)-th stage as \(k_{N1}=N_{0}/N_{consum}\). The dependence of \(k_{N1}\) on the parameter \(H_{mix}\)/\(D\) indicates that an increase in the filling height of the mixture with a constant diameter led to an increase in the power consumption of the mixer (Figure 5). The coupled analysis of the effects of \(H_{mix}\)/\(D\) on the homogeneity coefficient of the mixture \(K_{clm}\) and on the power factor \(k_{N1}\) shows that, with an increase in the loading height of the foam concrete mixture at the ratio \(H_{mix}\)/\(D\) from 1 to 2, there was a sharp decrease in the homogeneity of the mixture. This indicates a decrease in the mixing efficiency in the upper zone of the mixture. At the same time, starting from the value of the ratio \(H_{mix}\)/\(D=1.5\), some stabilization of \(k_{N1}\) was observed. This indicates that a further increase in the mixture height led to a decrease in the efficiency of mixing and aeration of the upper layers of the mixture. Thus, the parameter \(H_{mix}\)/\(D\) in the range of 0.75-1 is optimal for a foam concrete mixture.