## 3 Results
### Physical Properties  
This section presents the physical properties analyzed for the different mortar types. Firstly, Figure 5 shows the results obtained for bulk density and thermal conductivity. As can be seen in Figure 5, mortars made with recycled concrete aggregate had a lower bulk density compared to traditional mortars made with natural sand. Additionally, incorporating natural fibers in these recycled mortars causes a slight reduction in density. This trend is observed for both cement/aggregate ratios, where it should be noted that mortars with a 1:4 ratio have a lower bulk density. This slight decrease in density has already been observed in other studies [84]. However, in the case of this research, it was not very significant since the natural fibers are incorporated as an addition and not as a replacement for the aggregate. On the other hand, it is observed that the bulk density decreases experienced by mortars made with RCA translates into a decrease in their thermal conductivity. This improvement in thermal resistance has become crucial to the application of these products made with secondary raw materials in the construction sector [85]. Furthermore, no significant differences in terms of thermal conductivity were observed between samples made with cement/aggregate ratios of 1:3 and 1:4 by weight, except for the reference sample of conventional mortar. [PERSON] et al. also corroborate how the addition of natural fibers reduces the thermal conductivity of masonry mortars [86]. In this sense, the addition of toquilla straw fiber produced the most significant improvements, decreasing the thermal conductivity of the recycled mortars by 24.2% and 29.5% for dosages with cement/aggregate ratios of 1:3 and 1:4, respectively. This decrease in thermal conductivity was expected because the fibers used have a lower thermal conductivity compared to the mortar matrix. In addition, the incorporation of fibers in the matrix tends to generate porosity and air in the matrix, improving the thermal resistance of the composite. On the other hand, the behavior of the different mortar types produced against the action of water has been analyzed. Table 8 shows the results of the capillary water absorption and open porosity tests. Figure 5: Thermal conductivity (bars) and bulk density (points) of the analyzed mortars. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & **Capillarity Water** & & **Capillarity Water** & \\  & **Absorption** & **Open Porosity (\%)** & **Sample** & **Absorption** & **Open Porosity (\%)** \\  & **(kg/m\({}^{2}\cdot\)min\({}^{0.5}\))** & & & **(kg/m\({}^{2}\cdot\)min\({}^{0.5}\))** & \\ \hline NA–1:3 & 0.41 \(\pm\) 0.03 & 67.3 \(\pm\) 0.9 & NA–1:4 & 0.39 \(\pm\) 0  
As seen in Table 8, the capillary water absorption coefficient of mortars made with recycled sand is much higher than that of traditional mortars made with natural sand. This phenomenon, attributed to the type of aggregate, has already been observed in previous research, where it was related to the higher water absorption capacity of recycled aggregates [87]. In addition, capillary absorption is inversely proportional to pore size, so mortars made with a cement/aggregate mass ratio of 1:4 have a lower absorption, although they would have a higher water vapor permeability [88]. Finally, as [PERSON] et al. point out, capillarity is linked to the internal communication between the pores, so the incorporation of natural fibers causes a reduction in the capillarity coefficient that can be attributed to the clogging of the pores by these reinforcing materials [44]. For the three types of natural fibers studied, the addition of abaca fiber was the one that achieved the greatest reduction in capillarity in mortars with RCA. On the other hand, the open porosity of the mortars with a cement/aggregate ratio of 1:4 by mass was higher than that obtained for the samples made with a 1:3 ratio.