## 3 Results and Discussions  
The experimental results, presented as mean values from five repeated tests for each proposed mixture, provided relevant information regarding the evolution of water absorption at the surface of the tested cementitious composite materials in relation to the content of nanoparticles introduced in their composition as an indirect indicator of hydrophilicity and on the kinetics of the process. As an influencing factor of the absorption mechanisms, the porosity of the developed cementitious composites with TiO\({}_{2}\) addition is currently not considered relevant; specific tests revealed scarce variation among the evaluated compositions, namely a 2.6 mean square deviation, which allows the assumption of a rather constant value of porosity with inconsistent effect upon the recorded absorption results as shown in Table 1. There is an almost constant porosity in the case of the samples containing 1%, 2%, 3% and 5% nano-TiO\({}_{2}\). However, for samples with 3.6% and 4% nano-TiO\({}_{2}\), a minimum level of material porosity was observed. In accordance with the literature [18; 20; 21; 22], although slightly influenced by the addition of nano-TiO\({}_{2}\), this parameter does not directly proportionally vary with the amount of nanoparticles introduced in the cementitious matrix, with a porosity reduction compared with the control sample being between 0.7%-5.2%, except for the two extreme samples. Thus, the surface water absorption of the samples is presented in Figure 3, depending on the type of mixture tested, the volume of sprayed water and the type of exposure (with or without UV exposure). As shown in Figure 3, the surface water absorption increases continuously and constantly with the increase in the amount of sprayed water for all the analyzed cases. This behavior of the phenomenon shows that an evaluation of the kinetic process by the rate of evolution of the water absorption process (indicator v) is suitable and can be used to determine this parameter. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline
**\% TiO\({}_{2}\)** & **0** & **1** & **2** & **3** & **3.6** & **4** & **5** & **6** & **10** & **Average** & **STDEV** \\ \hline Porosity (\%) & 15.1 & 14.9 & 14.7 & 14.2 & 7.5 & 10.7 & 14.7 & 15.0 & 14.5 & 13.5 & 2.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Porosity of the cementitious composite materials. It is noted that the maximum water absorption was achieved by mixture P8, containing 6% TiO\({}_{2}\), for all situations of the amount of sprayed water, therefore it is appreciated that this composite matrix shows the highest hydrophilicity, both in non-exposure to UV conditions and also to 1 h exposure to the action of UV rays. Regarding the samples exposed to 1 + 24 h for UV action, the maximum water absorption was initially recorded for the mixture P5 (3.6% TiO\({}_{2}\)), closely followed by mixture P8 (6% TiO\({}_{2}\)); when the amount of sprayed water was increased as the test continued, an increase of water absorption was observed for all specimens ranging from P2-P8 (1% to 6% TiO\({}_{2}\)) intervals. Increasing the amount of TiO\({}_{2}\) in the mixtures over 6% (mixtures with 10% TiO\({}_{2}\)) determines the reduction of water absorption at the surface, which indicates the reduction of hydrophilicity. P2 (1% TiO\({}_{2}\)) and P3 (2% TiO\({}_{2}\)) specimens, unexposed to UV action and with 1 h UV exposure, indicate quite small changes in hydrophilicity when compared to the control samples; this proves that an addition of 1%-2% TiO\({}_{2}\) in the cementitious matrix is insufficient. The slight flattening of the curve with the increase of the amount of sprayed water can be considered the tendency of phenomenon stabilization when reaching a peak of water absorbed on the surface, after which the excess water has a chance to slip on the existing film.