# Cement Pastes with Hygyroscopic Polymeric Additions for Potential Building Applications
## 3 Results and Discussion
### Porosity Distribution  
The graphs in Figure 1 show the averages of three porosity distributions for each sample during aging (the first three rows at 3, 14, and 28 days, respectively) and after a 200 \({}^{\circ}\)C thermal treatment of samples aged for 28 days. After the thermal treatment, all the samples exhibited significant weight loss [23; 24] due to water evaporation, as detailed in Table 3.  
After 3 days of curing, the distribution of CS mainly consisted of mesopores, which had widths between 2 and 50 nm [39]. Microporosity increased with curing time and thermal treatment. Both the additions, SA-PA and fibers, increased the number of macropores, ensuring that permeability increased with curing and even after thermal treatment. It is already known that the macroporosity of SA-PA is higher compared with CS samples [1; 38], but macropores increase even more in the presence of polyamide fibers (NY/SA-PA). Macropores must also be due to the less homogeneous and workable paste, as observed  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Sample** & **Time (s)** \\ \hline CS & \(17\pm 1\) \\ SA-PA & \(11\pm 1\) \\ NY & \(5\pm 2\) \\ NY/SA-PA & \(5\pm 3\) \\ \hline \hline \end{tabular}
\end{table}
Table 2: Times that fresh samples needed to reach a viscosity limit of 390 mPa\(\cdot\)s at a rate of 1.5.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Sample** & \begin{tabular}{c} **Total** \\ **Porosity** \\ **after 3 Days** \\ **of Aging (\%)** \\ \end{tabular} & \begin{tabular}{c} **Total Porosity** \\ **after 14 Days of** \\ **Aging (\%)** \\ \end{tabular} & \begin{tabular}{c} **Total Porosity** \\ **after 28 Days of** \\ **Aging (\%)** \\ \end{tabular} & \begin{tabular}{c} **Total Porosity** \\ **after 28 Days of** \\ **Aging (\%)** \\ \end{tabular} & \begin{tabular}{c} **Total Porosity** \\ **after 28 Days of** \\ **Aging (\%)** \\ \end{tabular} & \
\begin{tabular}{c} **Weight Loss after 28 Days** \\ **after the Thermal** \\ **Treatment at 200 \({}^{\circ}\)C** \\ **for 1 h (\%)** \\ \end{tabular} &
\begin{tabular}{c} **Weight Loss after 28 Days** \\ **of Aging and after the** \\ **Thermal Treatment at \\ 200 \({}^{\circ}\)C for 1 h (\%)** \\ \end{tabular} \\ \hline CS & \(16\pm 2\) & \(19\pm 3\) & \(29\pm 1\) & \(36\pm 1\) & \(27\pm 1\) \\ SA-PA & \(18\pm 3\) & \(29\pm 1\) & \(32\pm 2\) & \(41\pm 1\) & \(27\pm 1\) \\ NY & \(24\pm 5\) & \(20\pm 2\) & \(20\pm 2\) & \(43\pm 1\) & \(28\pm 2\) \\ NY/SA-PA & \(17\pm 1\) & \(20\pm 3\) & \(23\pm 1\) & \(41\pm 2\) & \(26\pm 2\) \\ \hline \hline \end{tabular}
\end{table}
Table 3: Weight loss percentages of samples cured for 28 days after the thermal treatment at 200 \({}^{\circ}\)C and the total porosity percentages.  
during viscosity measurements; this lets air remain entrapped around fibers. The number of mesopores decreased during aging for all the samples and even after thermal treatments, but the size distribution was asymmetrical toward larger sizes. The samples containing fibers showed a bimodal pore distribution, with micropores (having widths < 2 nm [39]) and macropores (having widths > 50 nm [39]). This bimodal distribution maintains with aging and even after the heat treatment at 200 \({}^{\circ}\)C, if SA-PA is present. Macropores allow internal core access and prevent the growth of pore pressure. Macrovoids could also increase by softening and flowing of fiber, whereas SA-PA residuals absorb diffusing water. Accordingly, the pore distribution data, obtained from MIP measurements, confirmed these mixtures as a strong tool to investigate the evolution of paste microstructures during aging and after thermal treatment.