# Impact of Fiber Type on Chloride Ingers in Concrete: A MacroXRF Imaging Analysis
## 3 Results
### Resistance to Chloride Penetration  
In total, 20 slices measuring 5 cm in height by 10 cm in diameter were submitted to the non-stationary chloride migration test. Of these, 15 slices were used for verification by colorimetry and 5 for verification by X-ray fluorescence (MacroXRF). At the start of the test, it was found that all the samples had initial currents (voltage U\({}_{i}\) = 30 V) of between 40 and 120 mA, and it was necessary to adjust the voltage (U\({}_{f}\)) so that they were all kept in the test for 24 h. In this context, concretes with a high initial current indicate a greater speed in the ion migration process and, therefore, a low resistance to chloride penetration.  
Table 5 shows the penetration results, Xd (mm), and the migration coefficient in the non-steady state (D\({}_{\text{ns}}\)) obtained for each of the samples tested using Equation (1) presented earlier in this work.  
Figure 8: Box plot of concrete compressive strength means (MPa). Different lowercase letters indicate differences between means at a 5% significance level.  
The analysis of variance, conducted at a 95% confidence level, revealed a significant interaction between all the variables, i.e., between the type of fiber and the fiber content incorporated into the concrete, indicating that these variables had an impact on the coefficient (Dns).  
Figure 9 presents a box plot of the averages of the migration coefficients in the non-steady state (Dns), at a confidence level of 95%, for the different concrete mixtures. The letters indicate groups that were statistically similar or distinct from one another.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline
**Mixture Type** & **Samples** & \begin{tabular}{c} **Penetration** \\ **Depth Xd** \\ **(mm)** \\ \end{tabular} & \begin{tabular}{c} **Voltage Uf** \\ **(V)** \\ \end{tabular} & \begin{tabular}{c} **Dns** \\ **(V)** \\ \end{tabular} & \begin{tabular}{c} **Dns** \\ **(\(\times\)10\({}^{-12}\)m\({}^{2}\)/s)** \\ \end{tabular} & \
\begin{tabular}{c} **Dns,mean** \\ **(\(\times\)10\({}^{-12}\)m\({}^{2}\)/s)** \\ \end{tabular} &
\begin{tabular}{c} **Standard** \\ **Deviation** \\ **(\(\times\)10\({}^{-12}\) m\({}^{2}\)/s)** \\ \end{tabular} \\ \hline \multirow{3}{*}{RC} & CP1 & 26.29 & 30 & 12.50 & & \\ \cline{2-6}  & CP2 & 24.43 & 30 & 11.57 & 11.85 & 0.55 \\ \cline{2-6}  & CP3 & 24.29 & 30 & 11.50 & & \\ \hline \multirow{3}{*}{GF25} & CP1 & 26.71 & 30 & 12.72 & & \\ \cline{2-6}  & CP2 & 25.43 & 30 & 12.07 & 13.05 & 1.17 \\ \cline{2-6}  & CP3 & 25.17 & 25 & 14.35 & & \\ \hline \multirow{3}{*}{GF50} & CP1 & 21.07 & 25 & 11.86 & & \\ \cline{2-6}  & CP2 & 20.43 & 25 & 11.47 & 12.03 & 0.67 \\ \cline{2-6}  & CP3 & 22.57 & 25 & 12.77 & & \\ \hline \multirow{3}{*}{PF25} & CP1 & 28.57 & 30 & 13.66 & & \\ \cline{2-6}  & CP2 & 30.29 & 30 & 14.52 & 14.19 & 0.46 \\ \cline{2-6}  & CP3 & 30.00 & 30 & 14.38 & & \\ \hline \multirow{3}{*}{PF50} & CP1 & 20.43 & 25 & 11.47 & & \\ \cline{2-6}  & CP2 & 23.14 & 25 & 13.12 & 11.99 & 0.98 \\ \cline{1-1} \cline{2-6}  & CP3 & 20.29 & 25 & 11.38 & & \\ \hline \end{tabular}
\end{table}
Table 5: Chloride ion migration test results.  
Figure 9: Box plot of Dns coefficients (m\({}^{2}\)/s). Different lowercase letters indicate differences between means at a 5% significance level.  
Looking at Table 5, we can see that the average D\({}_{\rm ns}\) varied between 11.85 \(\times\) 10\({}^{-12}\) m\({}^{2}\)/s and 14.09 \(\times\) 10\({}^{-12}\) m\({}^{2}\)/s. It is important to note that the higher the value of the migration coefficient (D\({}_{\rm ns}\)), the lower the concrete's resistance to chloride ion penetration.  
It is clear that when comparing each pair of sample groups, the average differences were low and, for the most part, non-existent. The PF25 group differed statistically from the RC and PF50 mix types, as shown in Figure 9, where the PF25 group is represented by the letter \"a\", as distinct from the letter \"b\", assigned to the RC and PF50 groups.