## 2 Materials and Methods
### Preparation of Mortar  
The mortar was wet sieved from fresh self-compacting SFRC to keep consistent with the bond performance of steel fiber in concrete matrix. All the raw materials of self-compacting SFRC are the same as the previous study [32]. The cement was ordinary silicate cement of grade P.O 42.5 with a density of 3195 kg/m\({}^{3}\) and compressive strength of 28 d \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**No.**} & \multirow{2}{*}{**Type**} & \multicolumn{4}{c}{**Cross-Section**} & \multirow{2}{*}{\(l_{t}\) (mm)} & \multirow{2}{*}{\(l_{t}/d_{t}\)} & \multirow{2}{*}{\(N_{\text{sf}}\)} & \multirow{2}{*}{\(f_{\text{sf}}\) (MPa)} \\ \cline{3-3} \cline{5-8}  & & & **Perimeter** & & & & & & **(MPa)** \\ \hline HFb & Hooked-end & Circular & 1.57 & 0.50 & 29.8 & 60.0 & 21,637 & 1150 \\ HF2 & Hooked-end & Circular & 2.20 & 0.70 & 31 & 44.3 & 10,680 & 1150 \\ HF3 & Hooked-end & Circular & 2.51 & 0.80 & 50.6 & 63.3 & 5006 & 1500 \\ HF4 & Hooked-end & Circular & 3.00 & 0.84 & 38 & 45.2 & 5980 & 600 \\ HF5 & Hooked-end & Circular & 2.83 & 0.90 & 51 & 56.7 & 3990 & 1150 \\ HF6 & Hooked-end & Circular & 2.36 & 0.75 & 60 & 80.0 & 4800 & 2200 \\ CF & Crimped & Rectangular & 5.33 & 1.17 & 38.8 & 33.2 & 3347 & 800 \\ CF2 & Crimped & Circular & 2.20 & 0.70 & 37.5 & 53.6 & 8830 & 2000 \\ IF1 & Indentation & Rectangular & 5.00 & 1.13 & 32.3 & 28.5 & 4599 & 550 \\ IF2 & Indentation & Irregular & 4.18 & 1.12 & 32 & 28.6 & 3550 & 1500 \\ IF3 & Indentation & Irregular & 6.20 & 0.82 & 36.5 & 44.5 & 1660 & 1700 \\ IF4 & Indentation & Irregular & 1.80 & 0.50 & 24 & 48.0 & 26,540 & 1400 \\ MF & Milled & Irregular & 2.51 & 0.80 & 31 & 38.8 & 8180 & 850 \\ LF & Large-end & Rectangular & 3.46 & 0.77 & 52.2 & 67.4 & 5027 & 350 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The characteristic parameters of deformed steel fibers. Figure 1: Different deformed steel fibers. of 53.8 MPa. The mineral admixture was class-II fly ash with a density of 2349 kg/m\({}^{3}\) and an activity index of 80.9%. The crushed limestone was continuous grading with a maximum particle size of 16 mm. The manufactured sand with a fineness modulus of 2.73, an apparent density of 2740 kg/m\({}^{3}\) and a stone-powder content of 7.3%. The water reducer was a high-performance polycarbonate acid type with a water-reducing rate of 30% and a solid content of 35%. The mix water was tap-water. Self-compacting SFRC was prepared by using the mix proportion design method based on the steel fiber-aggregate skeleton packing test [18; 34; 35]. The steel fiber, marked as HFb in reference [32], was used with a volume fraction of 1.2%. The detailed mix proportion, the workability, and the basic mechanical properties of self-compacting SFRC and wet-sieved mortar are presented in Table 2. The cube compressive strength\(f_{\text{cu}}\) and splitting tensile strength\(f_{\text{st}}\) of self-compacting SFRC were tested according to the specification of China code GB/T50081 [36]. The compressive strength\(f_{\text{cm}}\) and flexural strength\(f_{\text{fm}}\) of wet-sieved mortar were tested according to the specification of China code GB/T17671 [37]. Both self-compacting SFRC and wet-sieved mortar had excellent fresh workability. The mixing procedure of self-compacting SFRC was the same as the previous study [18]. Figure 2 presents the detailed wet-sieved process of mortar. First, a certain amount of fresh self-compacting SFRC was put in a sieve with a square hole of 5 mm diameter. Then, the fresh mortar with steel fibers were sieved out. After the steel fibers were sucked out using the magnet, the wet-sieved mortar was obtained.