## 3 Results
### Physicochemical Properties  
The main species present in the mortars under study were identified by XRD, with no significant differences observed. Figure 2 represents the XRD diffractogram corresponding to G-10, showing the majority species in the sample. Portlandite, sand quartz and the anatase and rutile phases of the photocatalyst were identified [6; 23]. The signals corresponding to anatase and rutile were observed in the W-5, W-10, G-5 and G-10, confirming that the TiO\({}_{2}\) maintains its structural integrity in the mortar specimens. The product of portlandite carbonation, calcium carbonate, was not detected in a routine XRD diffractogram. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sample** & **Initial Setting Time** & **Final Setting Time** & **Setting Time** \\ \hline
**W** & 2 h 51 min & 3 h 41 min & 50 min \\ \hline
**W-5** & 1 h 52 min & 2 h 32 min & 40 min \\ \hline
**W-10** & - & - & - \\ \hline
**G** & 2 h 45 min & 4 h 36 min & 1 h 51 min \\ \hline
**G-5** & 1 h 52 min & 3 h 22 min & 1 h 30 min \\ \hline
**G-10** & 1 h 40 min & 2 h 30 min & 50 min \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Setting times. Figure 1: Compression strength. (**a**) G-samples (**b**) W-samples. The degree of hydration and the percentage of portlandite in the mortars were determined from the thermogravimetry analyses. Four thermal regions can be seen in the curve that was obtained (Figure 1). The first region is due to the loss of free and adsorbed water. The second corresponds to decomposition of the calcium hydroxide (portlandite) and the subsequent evaporation of water. \[\text{Ca(OH)}_{2}\rightarrow\text{CaO}+\text{H}_{2}\text{O} \tag{4}\]  
The next region corresponds to decomposition of calcium carbonate, which is the result of carbonation of the sample through the reaction of portlandite with carbon dioxide in the air. \[\text{CaCO}_{3}\rightarrow\text{CaO}+\text{CO}_{2} \tag{5}\]  
Table 3 shows the percentage of hydration and of portlandite in each of the mortars studied. In the case of cement G, it can be seen that both the hydration and portlandite percentages remain practically unaltered with the addition of TiO\({}_{2}\). However, in the case of cement W, both percentages decreased slightly as the amount of photocatalyst increased. This is consistent with the increasing dryness of these samples. The results obtained are similar to those obtained by [PERSON] et al [24], with percentages of around 29-30%. The hydration percentages are around 2.5-3%, similar to values published in other studies [25]. \begin{table}
\begin{tabular}{c c c} \hline
**Samples** & **\%Hydration in the Mortar** & **\%Portlandite (\%Ch) in the Cement** \\ \hline
**W** & 3.31 & 32.9 \\ \hline
**W-5** & 2.96 & 30.9 \\ \hline
**W-10** & 2.47 & 29.7 \\ \hline
**G** & 2.91 & 29.3 \\ \hline
**G-5** & 3.07 & 29.4 \\ \hline
**G-10** & 3.06 & 30.0 \\ \hline \end{tabular}
\end{table} 
Table 3: Percentages of hydration and portlandite in the studied mortars. Figure 2: X-ray diffraction (XRD) of G-10. Sample porosity was measured at 28 days. Table 4 shows the microstructural characteristics of the mortars in terms of porosity and mean pore size. An increase in porosity was observed in both cements due to the presence of the photocatalyst, which explains the previously mentioned decrease in strength. Cement G porosity rose from 7.14% to 12.20% and 11.58% for G-5 and G-10, respectively, while cement W porosity rose from 7.26% to 9.39% and 10.12% for W-5 and W-10, respectively, as a result of the presence of the photocatalyst. Figure 3 shows pore volume distribution for all the samples. The pore diameter range is the same for all the samples. That is, they all display porosity in the interval \(7\times 10^{-3}\) to 200 \(\upmu\)m. As for pore size distribution, practically no change was observed in the case of cement G when the photocatalyst was present. However, for cement W, a noticeably marked shift to larger pore sizes was observed with W-10.