## 3 Results and Discussion  
Results of the Effect of Processing Cement and Cement Paste in the VLA on the Compressive Strength of Cement-Sand Mortar  
The results obtained as a result of the first stage of research are presented in Table 10 and Figure 5.  
Analysis of the data obtained shows that an increase in the processing time of cement leads to an increase in its fine fractions. Thus, for untreated cement, the number of particles with a diameter of up to 20 microns is 42%, and for cement treated for 150 s--79%. The dependence of the specific surface area of cement on the duration of its processing in the VLA is presented in Table 10.  
These changes in the dispersion of cement lead to an increase in the strength of the cement-sand mortar (CSM), which is confirmed by the test results of beam specimens given in Table 11, where the compressive strength is expressed in terms of average value \(\pm\) the standard deviation. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Composition Number** & **Processing Time in VLA, s** &
\begin{tabular}{c} **The Specific Surface Area of** \\ **Cement Particles, cm\({}^{2}\)/g** \\ \end{tabular} \\ \hline
1 & 0 & 2930 \\
2 & 50 & 3518 \\
3 & 100 & 3740 \\
4 & 150 & 4980 \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Influence of the processing time of cement in the VLA on its specific surface. Figure 5: Dependence of the distribution of cement particles by fractions with a change in the processing time of cement in the VLA. After analyzing the results obtained, it was found that when processing the cement paste in the VLA for 100 s, the maximum increase in the strength of the hardened cement-sand mortar is observed. Thus, the increase in the strength during processing for 100 s was 27%. However, with an increase in the processing time to 150 s, an adverse effect is observed. It is known that the activity of cement depends on the degree of its dispersion. With an increase in the specific surface area of cement, its strength characteristics increase. However, at the same time, water demand also increases, which negatively affects the strength characteristics of the binder. When the values of the specific surface area are close to 5000 cm\({}^{2}\)/g, the negative effect of the increase in water demand is significant, making further cement grinding impractical. Based on the results obtained, it was decided to activate the cement-sand mortar for 0 (control point), 50, 60, 70, 80, 90, 100 s.  
Influence of the Processing of Cement-Sand Mortar in the VLA on the Strength and Strain Characteristics of Lightweight Fiber-Reinforced Concrete  
The results obtained as a result of the second stage of research are presented in Table 12 (where the experimentally determined values of all the mechanical characteristics are expressed as average value \(\pm\) the standard deviation) and Figure 6. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Composition Number** & **Processing Time in VLA, s** &
\begin{tabular}{c} **Compressive Strength** \\ **CSM, MPa** \\ \end{tabular} \\ \hline
1 & 0 & 54.8 \(\pm\) 3.4 \\
2 & 50 & 65.1 \(\pm\) 4.0 \\
3 & 100 & 69.5 \(\pm\) 4.3 \\
4 & 150 & 53.9 \(\pm\) 3.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 11: Influence of the processing time of the cement paste in the VLA on the growth of the strength of the cement-sand mortar samples and the specific surface area of cement particles.