## 3 Results and Discussion
### Recommended Compositions of Various Types of Fiber-Reinforced Concrete  
As a result of the experiments, the compositions of heavy and fine-grained concrete were selected using a combination of various types of fiber, with the most effective volume concentrations of various types of fiber among themselves. Table 11 shows the composition options.  
Figure 15: Dependencies of the concrete deformation: 1—control composition; 2—concrete with a volume content of steel fiber 2% and basalt 2%; 3—concrete with a volume content of polypropylene fiber 1.5% and basalt 2.5%; 4—concrete with a volume content of steel fiber 2.5% and polypropylene 1.5%.  
In [53], the results of an experimental study of workability and mechanical properties of self-compacting concrete (SCC) with silica fume (SF) and various types of fibers were obtained. The authors used five types of fibers: hook-end steel (H), mild steel (M), carved steel (S), basalt rock (R), and polypropylene (P) fibers. Each fiber type was added to the concrete at 0.25% by volume of concrete, and a silica fume substitution rate of 30% by  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**E, \({}^{*}\)10\({}^{4}\)**} & \(\overline{\
u_{\rm RDH}}\), & \(\overline{\
u_{\rm RDH}}\) & \(\overline{\
u_  
weight of cement was applied. The results showed that the addition of fiber tends to reduce the quality of the fresh concrete. The corresponding compressive strength values were 34.5, 33.9, 32.1, 36.9, 35.8 and 33.3 MPa with the addition of fibers of types H, M, S, P and R at a test age of 28 days, respectively.  
In [54], the strength properties of fine-grained concrete reinforced with amorphous fiber and fiber based on mineral wool, basalt fiber, glass fiber, steel and polypropylene fibers were investigated. The analysis of the results was carried out by comparison with the characteristics of control samples without reinforcement. The best characteristics of the flexural strength were shown by the samples with amorphous fiber, and the highest compressive strength, with the steel fiber. The addition of amorphous fibers increased flexural strength by 56%, but decreased compressive strength by 30% compared to the control samples. The addition of steel fiber shows a 20% increase in flexural strength and a 14% increase in compressive strength, confirming the beneficial effect of adding commercially available fiber to fine concrete. The results obtained allowed the authors to develop compositions of fiber-reinforced concrete with a compressive strength of up to 38 MPa and a bending strength of up to 12 MPa.  
A review [55] examined concrete reinforced with steel fiber (SF), polypropylene fiber (PPF), basalt fiber (BF), and glass fiber (GF). Fiber reinforcement in recycled aggregate concrete (RAC) tends to enhance and retard crack propagation and thus lead to plastic behavior of the cementitious matrix. The authors emphasize that despite the growing interest in the use of FRC, there are still some doubts about the dosage and enhancing effects of the fibers.  
The authors note that SF is the most primitive and convincing material that shows promising results in terms of increasing the strength of RAC. SF volume fractions up to 0.7% improve compressive strength, while SF volume fractions up to 1.5% result in significant increases in flexural strength and tensile strength RAC. PPF volume fractions in the range of 0-1.25% successfully lead to increased compressive strength, flexural strength at load, and tensile strength RAC. BF is widely recognized as an environmentally friendly twenty-first century fiber that effectively bridges cracks in weak RACs and results in increased tensile strength. BF volume fractions in the 0-1.5% range lead to significant increases in compressive strength, flexural strength at load and tensile strength RAC.  
Comparison of the data obtained in [53; 54; 55] shows that the results obtained in this article are in good agreement with the results of other researchers.