## 2 Methodology
### Materials and Dosages Used
#### 2.3.2 Aggregates  
The physical characterization of the aggregates used was carried out following the UNE-EN 13139: 2002 standard [43]. The results obtained are shown in Table 3.  
As shown in Table 3, the percentage of fineness in recycled aggregates is higher than that of natural aggregate, with the aggregate from ceramic waste having the highest value of this property (almost double the natural aggregate). This higher percentage of fines leads to higher water absorption and lower final mortar resistance. On the other hand, both aggregates from CDW present lower density values compared to natural aggregate, with the aggregate from ceramic waste having the lowest density.  
The granulometric distribution of aggregates used for the preparation of the mortars used in this investigation was obtained according to the UNE-EN 933-2: 1996 and UNE-EN 933-1: 2012 standards [44, 48]. The results are shown in Figure 3. In the case of aggregates from CDW, the fine fraction between the bottom and that retained in the 0.063 sieve was eliminated to improve the workability of the mortar. All the distribution curves of the aggregates presented are continuous and located within the limits of the regulations.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline  & & & & & & & & & & & & & \\ \hline Al\({}_{2}\)O\({}_{3}\) & CaO & Fe\({}_{2}\)O\({}_{3}\) & K\({}_{2}\)O & MgO & SiO\({}_{2}\) & TiO\({}_{2}\) & MnO & P\({}_{2}\)O\({}_{5}\) & SO\({}_{3}\) & BaO & SrO & Others \\ \hline
4.02 & 67.30 & 3.39 & 0.65 & 1.23 & 18.33 & 0.19 & 0.06 & 0.12 & 4.31 & 0.06 & 0.07 & 0.27 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Characteristics of the type CEM II B/L-32.5 N cement used.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Test** & **Fine** & **Particle** & **Fineness** & **Fiability** & **Bulk. Dens,** & **Dry Dens.** & **Water** \\  & **Content (\%)** & **Form** & **Modulus (\%)** & **(\%)** & **(kg/m\({}^{3}\))** & **(kg/m\({}^{3}\))** & **Absorption (\%)** \\ \hline
**Standard** & UNE EN & UNE-EN & UNE-EN & UNE-EN & UNE-EN & UNE-EN & UNE-EN & UNE-EN & UNE-EN 1097-6 \\  & 933-1 [44] & 13139 [43] & 13139 [43] & 146404 [45] & 1097-3 [46] & 1097-6 [47] & 1097-6 [47] \\ \hline
**NA** & 2.45 & - & 4.26 & 21.33 & 1542 & 2503 & 0.96 \\ \hline
**RA-Cer** & 4.53 & Not relevant & 5.56 & 25.11 & 1254 & 2124 & 7.58 \\ \hline
**RA-Con** & 3.91 & Not relevant & 4.12 & 23.98 & 1321 & 2204 & 5.87 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Physical characterization of natural aggregate (NA), recycled arid ceramic (RA-Cer) and R-recycled concrete aggregate (RA-Con).  
Finally, the crystalline phases in the aggregates from construction and demolition waste used in this investigation were also identified. An X-ray diffraction test was carried out using a Siemens D5000 Diffractometer with a graphite monochromator. A Cu-K\(\alpha\) monochromatic X-ray beam with wavelength of \(\lambda\) = 1.540598 A was used. In Figure 4, the results obtained can be seen at a rate of passage of the first beam every 20 s and were analyzed using the EVA software from the Bruker company, which is the characteristic of the diffractometer.  
The crystalline phases found in Figure 4 after the analysis of the aggregates used in this study show broad peaks and low intensities (except for quartz). This behavior is typical of compounds which have amorphous phases or a low level of crystallization, mainly caused by the components formed in the hydration of the concrete and materials that come from ceramic elements that have undergone grinding processes, as was the case for the recycled aggregates used [50].  
Figure 4: Diffractogram corresponding to the recycled ceramic aggregate and the recycled concrete aggregate.  
Figure 3: Recycled aggregate size distribution curve compared to the limits of NBEFL 90 [49] adapted to the sieve size established by UNE-EN-933-2 [48].