## 3 Experimental Results and Discussion
### Flexural Strength and Residual Flexural Strength  
The average load F\({}_{\text{L}}\) and F\({}_{\text{1}}\) to F\({}_{\text{4}}\), average flexural strength \(f_{L}\), and the average residual flexural strength \(f_{R1}\) to \(f_{R4}\) for the three concrete batches are summarized in Table 5. These results were obtained from the recorded load vs. CMOD graphs using Equations (1) and (2). The corresponding load vs. CMOD graphs are presented in Figure 4 \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Batch Designation**} & **Compressive Strength,** & **Split Tensile** & **Modulus of Elasticity,** \\  & \(f_{cm}\) **(MPa)** & **Strength,\(f_{ct.sp}\) (MPa)** & **\(E_{c}\) (MPa)** \\ \hline FF4 & 69.5 [0.91] & 3.89 [0.10] & 34,153 [3535.6] \\ FF6 & 69.6 [1.39] & 5.00 [0.41] & 32,687 [818.9] \\ FF8 & 52.7 [0.90] & 2.28 [0.58] & 28,968 [3491.4] \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Summary of the 28-day test results. Numbers in square brackets are standard deviation. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Batch**} & \multirow{2}{*}{\(\mathbf{F_{L}}\)} & \multirow{2}{*}{\(\mathbf{F_{1}}\)} & \multirow{2}{*}{\(\mathbf{F_{2}}\)} & \multirow{2}{*}{\(\mathbf{F_{3}}\)} & \multirow{2}{*}{\(\mathbf{F_{4}}\)} & \multirow{2}{*}{\(\mathbf{f_{L}}\)} & \multirow{2}{*}{\(\mathbf{f_{R1}}\)} & \multirow{2}{*}{\(\mathbf{f_{R2}}\)} & \multirow{2}{*}{\(\mathbf{f_{R3}}\)} & \multirow{2}{*}{\(\mathbf{f_{R4}}\)} \\  & & & **(KN)** & & & & & & **(MPa)** & \\ \hline FF4 & 16.13 & 5.58 & 5.65 & 5.38 & 4.60 & 5.16 & 1.78 & 1.81 & 1.72 & 1.47 \\ FF6 & 18.26 & 5.65 & 7.38 & 6.80 & 5.61 & 5.84 & 1.81 & 2.36 & 2.18 & 1.80 \\ FF8 & 15.32 & 9.45 & 11.28 & 10.66 & 9.00 & 4.90 & 3.02 & 3.61 & 3.41 & 2.88 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Summary of 28-day flexural test results. Average flexural strength \(f_{L}\) and residual flexural strength \(f_{Rj}\). Figure 4: Load vs. crack-mouth opening displacement (CMOD) for (**a**) FF4, (**b**) FF6 and (**c**) FF8. To prevent brittleness in a structural member, the _fib_ Model Code 2010 [34] suggest that fiber reinforcement can only be used if two conditions are satisfied: (i) \(f_{R1k}/f_{Lk}\geq 0.4\), and (ii) \(f_{R3k}/f_{R1k}\geq 0.5\), with \(f_{Lk}\), \(f_{R1k}\) and \(f_{R3k}\) being the characteristic value of the nominal strength at peak load, the characteristic serviceability limit at CMOD1 and characteristic ultimate limit at CMOD3, respectively. The characteristic values are calculated using normal distribution, with confidence interval of 0.75 [34]. Table 6 presents the characteristic values \(f_{Lk}\), \(f_{R1k}\), and \(f_{R3k}\) of all batches and the ratios \(f_{R1k}/f_{Lk}\) and \(f_{R3k}/f_{R1k}\). Table 7 presents the flexural strength ratio of all mixtures (rj) compared to FF4. It is reported in the literature that the flexural strength of SCC reinforced with monofilament polypropylene fibers is affected by the fiber content, and when compared with plain concrete the flexural strength of fiber reinforced concrete is significantly higher [17]. Another recent study on the fracture parameters and size effect of steel fiber-reinforced self-compacting concrete [36] found that an increase in the steel fiber dosage increases energy absorption and ductility. For high-strength SCC reinforced with twisted-bundle macro-synthetic fiber, the increase in fiber dosage from 4 kg/m\({}^{3}\) to 6 kg/m\({}^{3}\) increased the overall flexural performance (Table 7), however, the further increase to 8 kg/m\({}^{3}\) resulted in a reduction of 5% in the flexural strength. The same trend was observed in the compression strength and can be attributed to the poor self-compacting properties of FF8. However, the most prominent contribution of the additional 4 kg/m\({}^{3}\) was observed in the post-cracking behavior.