## 3 Results and Discussion
### Porosity Distribution of Dry Mortar References (Mix 1)  
The pore size distribution is derived from the BjH model. The most common classification is defined as the measured pore sizes that range from <2 nm to 300 nm, the microporosity refers to pores smaller than 2 nm, the mesoporosity indicates pores from 2 nm to 50 nm, and macroporosity refer to pores with sizes from 50 nm to 300 nm. According to [PERSON] [40], the dominant pore size in a current cement-based hardened paste is approximately 1.7 nm (micropore), which is associated with the pore size of the C-S-H gel, in fact these pores occur during hydration of gels (C-S-H and CH). On the other hand, it also depends on the W/C ratio (water/cement), the type of cement and the duration of cure. For mortars and concretes which contain aggregates, the pores are larger corresponding to sizes of mesopores and macroopres.  
Figure 4 shows the influence of the water ratio on the modification of the pore size distribution of the reference sample. In Mix 1 with the ratio w/b = 0.5, they have a monomodal pore size distribution with a peak around 30 nm (0.03 \(\upmu\)m) which corresponds to mesopores according to the classification above mentioned. According to [PERSON] [41], this size has 36% porosity. [PERSON] has investigated the percentage of porosity of cement-based pastes with different w/b ratio in terms of pore size.  
On the other hand, the rise in the w/b ratio = 0.6 generate a multimodal distribution. At least, two populations of pore sizes are present in these samples.  
A difference is clearly observed between the 0.5 and 0.6 ratio curves. This difference is illustrated in Figure 4 with arrows. The dominant size remains more or less in the same order of magnitude. For these two formulations with different amounts of water and whatever the level of compaction energy, the pore distribution curves deviate completely, this phenomenon is clearly illustrated in Figure 4.  
This phenomenon can be explained by the difference in the specific surface related to these formulations which is presented on Table 6. The formulation prepared with the ratio w/b = 0.6 has a specific surface area greater than that of 0.5. [PERSON] [40] has shown that when the water/ cement ratio increases in cementitious pastes, the specific surface area also increases. The author observed that there is a linear relationship between the specific surface area and the degree of hydration. Therefore, in our mixes, when the amount of water increases, the hydration reaction is higher and, in fact, the pores appear to be more present in the structure. In Table 7, the average pore size is presented according to the BjH method at the time of nitrogen gas adsorption and desorption. It is shown that the pore size of mixtures with a ratio of 0.6 is slightly larger than that observed with the ratio 0.5. This is in agreement with the curves in Figure 4.  
\begin{table}
\begin{tabular}{c c} \hline
**Mix 1** & **Specific Surface Area BET (m\({}^{2}\)/g)** \\ \hline Mix 1 (E * = 400 kN\(\cdot\)m/m\({}^{3}\)), w/b = 0.5 & 9.63 \\ Mix 1 (E = 600 kN\(\cdot\)m/m\({}^{3}\)), w/b = 0.5 & 9.36 \\ Mix 1 (E = 800 kN\(\cdot\)m/m\({}^{3}\)), w/b = 0.5 & 9.68 \\ Mix 1 (E = 1000 kN\(\cdot\)m/m\({}^{3}\)), w/b = 0.5 & 9.35 \\ \hline Mix 1 (E = 400 kN\(\cdot\)m/m\({}^{3}\)), w/b = 0.6 & 10.59 \\ Mix 1 (E = 600 kN\(\cdot\)m/m\({}^{3}\)), w/b = 0.6 & 11.77 \\ Mix 1 (E = 800 kN\(\cdot\)m/m\({}^{3}\)), w/b = 0.6 & 11.09 \\ Mix 1 (E = 1000 kN\(\cdot\)m/m\({}^{3}\)), w/b = 0.6 & 11.53 \\ \hline \end{tabular} Note. * E = compaction energy applied.  
\end{table}
Table 6: Specific surface area BET for Mix 1, (reference samples).