## 3 Results and Discussion
### Porosity Distribution of Activated Dry Mortars (Mix 2, Mix 3 and Mix4)  
Figure 8 shows the curves for samples activated with three types of activators and the two w/b ratios. All the curves show a size distribution of the multimodal pores. In Figure 8a, we observe four pore families for the w/b = 0.6 ratio regardless of the Na\({}_{2}\)CO\({}_{3}\) dosage and three pore populations for the w/b = 0.5 ratio. However, for all cases, the dominant pore size is between 0.03 and 0.04 um; these are mesopores. Figure 8: Pore size distribution of activated samples: (**a**) Mix 2 with Na\({}_{2}\)CO\({}_{3}\); (**b**) Mix 3 with Na\({}_{2}\)O\({}_{3}\)Si; (**c**) Mix 4 with CaCl\({}_{2}\). According to the total volumes of N\({}_{2}\) adsorbed by the pores (see Table 9), the sample containing 5% Na\({}_{2}\)CO\({}_{3}\) with the ratio of w/b = 0.5 has a low value of adsorption (0.0304 cm\({}^{3}\)/g) compared to the other samples in this series with addition of Na\({}_{2}\)CO\({}_{3}\). This is in good agreement with the related curve of this sample where the area under the curve is less compared to the others (see Figure 8a, curve in blue). The area of the curve is representative of the volume of voids in the structure. According to Figure 8a, addition of 5% Na\({}_{2}\)CO\({}_{3}\) results in a reduction in pore volume \(0.20>p>0.035\) micron. Increasing the w/b ratio by 0.1 results in an increase in pore volumes in the same range of 0.02 cm\({}^{3}\)/g. The behavior of samples treated with Na\({}_{2}\)O\({}_{3}\)Si is particularly remarkable (Figure 8b). The addition of the Na\({}_{2}\)O\({}_{3}\)Si allows for a shift in the peaks of the distribution curve (0.034 micron) towards larger-pore families (0.15 micron). At last, the addition of 1% more of CaCl\({}_{2}\), allows one to lower the pore volume by 0.01 cm\({}^{3}\)/g. To establish a link between the mechanical strength and the adsorption capacity of each sample, it is necessary to relate the values of the BET specific surface area and the values of the difference in volume of adsorption/desorption of the pores. In this series of samples, the one with 5% Na\({}_{2}\)CO\({}_{3}\) and ratio of w/b = 0.6, shows a large difference between the adsorption volume and the pore desorption volume of 0.0201 cm\({}^{3}\)/ g. Moreover, this sample has a high specific surface area. This suggests a very small pore size and the possibility of gas/liquid retention in the pores, and consequently a high mechanical resistance. This has been demonstrated by measuring the highest compressive strength of this series, where a value of 6.10 MPa was obtained. In Figure 8b, the pore distribution graphs for the samples activated by Na\({}_{2}\)O\({}_{3}\)Si are plotted. The dominant pore size for the dosage of 6% is larger than that with 3%; this size corresponds to 0.1 and 0.03 \(\mu\)m, respectively. The sample activated by 3% Na\({}_{2}\)O\({}_{3}\)Si has a higher adsorption volume than the others (0.0550 cm\({}^{3}\)/g) which corresponds to the volume of voids of material at the time of adsorption. This sample has a fairly high specific surface area, and, this results in a high resistance (compressive strength of 9.02 MPa has been measured). One can conclude that there exist several small pores. On Figure 8c, a distribution in size of the multimodal pores is also observed, for which at least three populations of size of the pores are present. The sample activated by 3% CaCl\({}_{2}\) shows a very low adsorption volume which is related to the volume of voids in the material. From the small specific surface area of this sample and the small difference in adsorption/desorption volume, it can be concluded that there are pores that are not necessarily small, but they are in small quantities. In addition, this sample has the highest mechanical strength in this sample series. The impact of microstructure evolution on UCS evolution is different depending on the nature of each additive.