## 3 Results and Discussion
### Complementary Physical Characterization Tests

Table 14: Loss of mass in grams and percentage decrease in flexural mechanical strength of specimens subjected to freeze–thaw cycling [74]. Figure 7 shows the results of the shrinkage test measured over a period of 100 days. As can be seen in Figure 7, mortars made with natural aggregate have a lower shrinkage during setting and have a higher dimensional stability for the same period of time in agreement with other previous studies [87]. On the other hand, the positive effect offered by the incorporation of aramid fibers to the mortar matrix made with recycled concrete aggregate can be appreciated, since it reduces shrinkage and hinders the appearance of cracks during setting [88]. It can also be seen how the dosages with a cement/aggregate ratio by weight of 1:4 have a lower shrinkage, which is due to their lower cement content and the RA-1:4-AF dosage being the one that is closest to the traditional mortar. The analysis of variance (ANOVA) performed for the statistical discussion of the durability tests on mortars made with recycled concrete aggregate is presented in Table 15.  
Figure 6: Flexural strength test results derived from the freezing test for cycled and uncycled specimens. Figure 7: Shrinkage evolution (mm/m) during setting evolution (days). As can be seen, after the analysis of Table 15, for the case of shrinkage, both factors, type of aggregate and incorporation of fibers, are statistically significant for the study, since they have a \(p\)-value lower than the significance level. This result is in agreement with the graph in Figure 7, where it can be seen that the dosages with cement/aggregate ratio 1:3 have a higher shrinkage and that it decreases with the incorporation of aramid fibers. However, in the case of durability under freeze-thaw cycles, the only significant factor for the analysis is the incorporation of aramid fibers, this reinforcement material being beneficial for the mechanical flexural strengths and statistically proven. On the other hand, in this case the cement/arid dosage is not statistically significant because, as can be seen in all the samples, there is a loss of mass which in turn is associated with a loss of flexural mechanical strength. Finally, and in accordance with the previous analyses, Tables 16 and 17 show the results obtained for the multiple range tests on mortars made with recycled concrete aggregate. Table 16 shows how for the multiple range test considering the dosage factor (cement/aggregate ratio), there are only significant differences in the homogeneous groups for the case of shrinkage. However, in Table 17, it can be seen how the analysis of homogeneous groups for the incorporation of fibers shows that for the durability properties studied, the incorporation of aramid fibers in the mortar matrix improves the performance of recycled mortars. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Property** & **Dosage** & **Count** & **LS Mean** & **LS Sigma** & **Homogeneous Group** \\ \hline Shrinkage (mm/m) & B & 6 & 0.44265 & 0.00419821 & X \\  & A & 6 & 0.49525 & 0.00419821 & X \\ \hline Freeze/Thaw Resistance: & B & 6 & 0.25667 & 0.02865020 & X \\ Flexural Strength (MPa) & A & 6 & 0.26333 & 0.02865020 & X \\ \hline \hline \end{tabular}
\end{table} 
Table 16: Multi-range test for shrinkage and flexural strength considering the cement/aggregate ratio. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Property** & **Fiber** & **Count** & **LS Mean** & **LS Sigma** & **Homogeneous Group** \\ \hline Shrinkage (mm/m) & AF & 6 & 0.43510 & 0.00419821 & X \\  & NF & 6 & 0.05028 & 0.00419821 & X \\ \hline Freeze/Thaw Resistance: & AF & 6 & 0.21167 & 0.02865020 & X \\ Flexural Strength (MPa) & NF & 6 & 0.30833 & 0.02865020 & X \\ \hline \hline \end{tabular}
\end{table} 
Table 17: Multi-range test for shrinkage and flexural strength considering the incorporation of aramid fibers.