## 2 Materials and Methods  
For fiber concrete mixture preparation, CEM II/AS 42.5 Portland cement with Blaine specific surface of 280 m\({}^{2}\)/kg was used. Chemical and mineralogy composition of the binder are shown in Table 1. Fine and coarse aggregates' grain size compositions are presented in Table 2. Aggregates meet the requirements of the following standards: DSTU B V.2.7-75-98 [27], DSTU B V.2.7-32-95 [28], BS EN 12620:2013 [29], ASTM C 33/C33M-18 [30]. Steel anchor fiber with diameter of 1 mm and length 50 mm was used as concrete reinforcement.  
Passage by weight of the applied crushed breakstone is 54.7% on a 10 mm sieve and 5% on a 5 mm sieve. According to the building codes, that is within the permissible limits of the following building codes: BS EN 12620: 2013 (sieve 10 mm not regulated, passage by sieve 5 mm in the range of 0-15%); ASTM C 33/ C33M-18 standart (10 mm sieve pass by weight in the range 0-10%); standard DSTU B V.2.7-75-98 (10 mm sieve passage by weight in the range of 20-70%, sieve 5 mm, passage by weight in the range of 0-10%).  
To preserve the workability of concrete mixtures, MasterGlenium SKY 608 plasticizer was used in an amount of 1.2% of the cement content (4.8 kg/m\({}^{3}\)). This percentage was determined as rational for repair concrete in preliminary studies [31; 32].  
For determining of concrete properties, 2 variable factors of concrete composition were chosen:  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Name of the Indicator** & **Value, \% by Mass** \\ \hline Tricalcium silicate, C\({}_{3}\)S & 66.95 \\ Dicalcium silicate, C\({}_{2}\)S & 13.15 \\ Tracalcium aluminate, C\({}_{3}\)A & 7.42 \\ Tetracalcium alumino/ferrite, C\({}_{5}\)AF & 12.48 \\ Calcium oxide, CaO & 64.49 \\ Silicone oxide, SiO\({}_{2}\) & 20.32 \\ Alumina oxide, Al\({}_{2}\)O\({}_{3}\) & 5.28 \\ Ferric oxide (III), Fe\({}_{2}\)O\({}_{3}\) & 4.05 \\ Magnesium oxide, MgO & 0.74 \\ Chlorine ion content, Cl & - \\ Insoluble residue, IR & 0.28 \\ Ignition lost, IL & 0.33 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Chemical and mineralogy composition of the CEM II/AS 42.5.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Sieve Size,**} & \multirow{2}{*}{**\% Passing by Weight**} & \multicolumn{2}{c}{**DSTU B**} & \multicolumn{2}{c}{**DSTU B**} & \multicolumn{2}{c}{**BS EN 12620:2013**} & \multicolumn{2}{c}{**ASTM C 33/C33M-18**} \\ \cline{2-9}  & & **Crushed** & **Sand** & **Crushed** & **Breakstone** & **Sand** & **Crushed** & **Breakstone** & **Sand** \\ \hline
20 & 100 & 100 & \(\geq\)90 & - & 90-99 & - & 90–100 & - \\
10 & 54.7 & 100 & 20–70 & - & - & - & 20–55 & 100 \\
5 & 5.0 & 100 & 0–10 & - & 0–15 & 100 & 0–10 & 95–100 \\
2.5 & 0.8 & 97.0 & - & 80–100 & 0–5 & 85–99 & 0–5 & 80–100 \\
1.25 & 0 & 83.5 & - & 55–95 & - & - & 50–85 \\
0.63 & 0 & 48.3 & - & 30–80 & - & - & 25–60 \\
0.315 & 0 & 28.6 & - & 20–50 & - & - & - & 5–30 \\
0.16 & 0 & 8.5 & - & 0–15 & - & - & - & 0–10 \\ \textless{}0.16 & 0 & 0.5 & - & - & - & - & - \\ \hline \hline \end{tabular}
\end{table}
Table 2: Comparison of fine and coarse aggregates’ sieve analysis according to different building codes.  
\(X_{1}\)**--amount of the hardening accelerator admixture Sika Rapid 3 from 0 to 2.4% of the cement mass (from 0 to 9.6 kg/m\({}^{3}\)); \(X_{2}\)**--amount of steel anchor fiber from 0 to 100 kg/m\({}^{3}\). Using the optimal symmetric 9-point plan with natural values of variable factors, lower (\(-\)1), middle (0) and upper (+1) limits of variation [33], test concrete mixtures were designed (Table 3). The maximum amounts of accelerator and fiber in the experiment were taken based on the recommendations of the manufacturers. Anchor fiber of this length was chosen as an effective dispersed reinforcement, taking into account the fact that with full depth repair technology, concreting is carried out to a depth of one-third of the entire thickness of a road slab.