## 3 Results
### Splitting-Test Tensile Strength  
Figure 7 denotes the relationship between the splitting-test tensile strength of PPFRC and the dosage of fiber volume. The lines shown in the figure represent the tensile strength (\(f_{sp}\)) trend obtained from a linear regression for the fiber lengths of 40, 50, and 60 mm; Pearson's correlation coefficients, \(r\), were 0.90, 0.94, and 0.93, respectively, showing strong, strong, and strong positive correlations. The determination ratios, \(r^{2}\), were 0.80, 0.88 and 0.86, respectively. Therefore, an excellent fit existed between the lines and strength behavior. As can be observed, this trend was more determined when the fiber length increased. However, the three lines denoted good regression and evidence that the tensile strength increased as the fiber dosage increased. The strength increase ratio for each variation of 0.4% fiber was 0.15, 0.27, and 0.30 MPa, for the fiber lengths of 40, 50, and 60, respectively. Considering that the standard deviation for the splitting-test tensile strength was 0.22 MPa, meaningful strength increases were obtained with the 50 and 60 mm fiber lengths, with values close to each other. Conversely, the concrete prepared with 40 mm fibers evidenced no significant strength increase. Tables 5 and 9 show the hypothesis \"t\" and Pearson tests, confirming the previous analysis. The hypothesis test \"t\" showed that in the mixtures with fibers of 50 and 60 mm in length, the null hypothesis was rejected in most cases, which states that the results were not statistically different from the results of the pattern mix without fibers. On the other hand, in the mixture with 40 mm fibers, the null hypothesis could not be rejected in most cases. Concerning the Pearson test, the null hypothesis was rejected in mixtures with 50 and 60 mm fibers, stating there was no correlation between the results. On the other hand, this hypothesis could not be rejected in mixtures with 40 mm fiber length. \begin{table}
\begin{tabular}{l l l l l l l} \hline \hline
**MV** & **IV** & **DV** & \(r^{2}\) & \(r\) & \(p\) & **Null Hypothesis** \\ \hline \(V_{f}=0.4\%\) & \(l\) & \(f_{cm}\) & 0.015 & 0.124 & 0.876 & no rejection \\ \(V_{f}=0.8\%\) & \(l\) & \(f_{cm}\) & 0.654 & 0.809 & 0.191 & no rejection \\ \(V_{f}=1.2\%\) & \(l\) & \(f_{cm}\) & 0.398 & 0.631 & 0.369 & no rejection \\ \hline \hline \end{tabular}  
MV—Moderating variable. IV—Independent variable. DV—Dependent variable.  
\end{table} 
Table 7: [PERSON]’s hypothesis test of the correlation between \(f_{cm}\) and \(l\). \begin{table}
\begin{tabular}{l l l l l l l l l} \hline \hline \multicolumn{3}{c}{**Variables**} & \multicolumn{6}{c}{**Variables**} \\ \hline
**IV1** & **IV2** & \multicolumn{3}{c}{**Q1**} & **Q2** & **Q3** & \multicolumn{3}{c}{**IV1**} & **IV2** & \multicolumn{3}{c}{**Q1**} & **Q2** & **Q3** \\ \hline  & \(V_{f}=0.00\%\) & - & & & & No fiber & - & & \\  & \(V_{f}=0.40\%\) & no & & & & \(l=40\) mm & no & & \\  & \(V_{f}=0.80\%\) & no & medium & no & \(V_{f  
Figure 8 denotes the results of the present study compared with other studies [54; 56; 63]. The observed trend was consistent with the results from previous studies. Several authors have concluded that adding plastic macrofibers in moderate volumes has a sensible influence on splitting-test tensile strength, from 20% to 50% [52]. A linear trend was observed in all the cases in the regression curves. Figure 9 denotes the relation between the splitting-test tensile strength of PPFRC and fiber length. The lines shown in the figure represents the splitting-test tensile strength (\(f_{sp}\)) trend obtained after a linear regression for the fiber dosages of 0.40%, 0.80%, and 1.20%; Pearson's correlation coefficients, \(r\), were 0.29, 0.91, and 0.98, respectively, showing weak, strong, and very strong positive correlations. The determination ratios, \(r^{2}\), were 0.09, 0.83 and 0.97, respectively. Therefore, a good fit existed between the lines and strength behavior.