# Photocatalytic Recycled Mortars: Circular Economy as a Solution for Decontamination
## 4 Results and Discussion
### Mineralogical Analysis  
The mineral phases formed in conventional and photocatalytic mortar families are shown in Figures 3 and 4, respectively. In all specimens, the main detected phase corresponds to quartz (SiO\({}_{2}\); 33-1161) [52]. The intensity decreased in all specimen patterns because the NS was replaced  
Figure 2: Mechanical strength comparison: (**a**) compressive strength; (**b**) flexural strength.  
with RS, which contains less silica [58]. The main phase in M100 was sanidine ((Na, K)(Si\({}_{3}\)Al)O\({}_{8}\); 10-0357) [52].  
The Portlandite phase (Ca(OH)\({}_{2}\); 04-0733) [52] and ettringite (Ca\({}_{6}\)Al\({}_{2}\)(SO\({}_{4}\))\({}_{3}\)(OH)\({}_{12}\)-26H\({}_{2}\)O; 41-1451) [52] were also observed in both families. The presence of these phases is an indicator of the Portland cement reaction [57], as shown by the mechanical performance of both mortar families (Figure 2). For this reason, the incorporation of RS into the mortar is compatible with the common Portland cement reaction.  
The other detected phases in the mortars corresponded to silicates such as illite (KAl\({}_{2}\)Si\({}_{3}\)AlO\({}_{10}\)(OH)\({}_{2}\); 02-0056) [52] and albite (Na(Si\({}_{3}\)Al)O\({}_{8}\); 10-0393) [52], which is in agreement with authors such as [PERSON] et al. [36] and [PERSON] et al. [14]. Regarding carbonates, all mortars showed calcite (CaCO\({}_{3}\); 05-0586) [52]; additionally, dolomite (CaMg(CO\({}_{3}\))\({}_{2}\); 36-0426) [52] was detected in M100 and all specimens of the photocatalytic mortar family. In both mortar families, it was observed that calcite (CaCO\({}_{3}\); 05-0586) [52] had a greater presence as the replacement of NS by RS increased. This behavior has also been recorded by authors such as [PERSON] et al. [58], who studied the replacement of natural siliceous sand with recycled aggregate. Gypsum (CaSO\({}_{4}\):2H\({}_{2}\)O; 33-0311) [52] was also detected in all specimens in both families, which could correspond to the RA or cement composition [36].  
Figure 3: X-ray diffraction patterns of conventional mortar family.  
Additionally, an SEM study was carried out, which supported the results obtained in the mineralogical study, as shown in Table 5. In the photocatalytic mortar family, no mineralogical phase attributed to Ti was detected; however, SEM confirmed the presence of TiO\({}_{2}\) in all mortars with Ph. CEM I.  
Figure 4: X-ray diffraction patterns of photocatalytic mortar family.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Element** & **M0** & **M20** & **M40** & **M100** & **PM0** & **PM20** & **PM40** & **PM100** \\ \hline C & 10.30 & 8.53 & 9.31 & 9.40 & 7.79 & 12.15 & 10.42 & 12.16 \\ O & 49.65 & 48.59 & 50.10 & 45.34 & 48.79 & 46.67 & 45.84 & 49.39 \\ Mg & 0.50 & 0.87 & 0.52 & 0.56 & 0.31 & 0.37 & 0.30 & 0.51 \\ Al & 2.30 & 2.95 & 2.36 & 3.89 & 1.78 & 3.00 & 3.74 & 1.96 \\ Si & 8.01 & 9.72 & 8.27 & 10.61 & 9.46 & 13.78 & 10.61 & 12.18 \\ S & 0.75 & 0.95 & 1.14 & 0.92 & 0.62 & 0.66 & 0.75 & 0.90 \\ K & 0.34 & 0.39 & 0.41 & 1.06 & 0.71 & 0.32 & 1.64 & 0.39 \\ Ca & 26.34 & 25.58 & 26.51 & 25.14 & 28.96 & 20.40 & 23.69 & 20.48 \\ Ti & 0.00 & 0.00 & 0.00 & 0.00 & 0.52 & 0.55 & 0.63 & 0.63 \\ \hline Total: & 100 & 100 & 100 & 100 & 100 & 100 & 100 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Average percentage, by weight, of elements by scanning electron microscopy (SEM).