# The Use of Volcanic Powder as a Cement Replacement for the Development of Sustainable Mortars
## 3 Results and Discussion
### Impedance Spectroscopy  
The R\({}_{1}\) and R\({}_{2}\) resistances have a relation with the electrolyte that fills the pores in the specimen [35]. The changes in the resistance value could come from the changes in the sizes of the pores or the pores drying [35; 37]. Figures 9 and 10 present the results of the R\({}_{1}\) and R\({}_{2}\) resistances, respectively, for mortars with CEM I, VP10, and VP20. For all the series, the R\({}_{1}\) resistances increased over time. In the case of the series with VP10, at short times the R\({}_{1}\) values were similar to those noted for CEM I. Nevertheless, from around 28 days, the R\({}_{1}\) resistances presented lower values than the reference series with CEM I, a trend that changes after 200 days, where the increase ratio of the VP10 series increased over CEM I, which means that after 270 days the VP10 series presented slightly higher values than the series with CEM I. Otherwise, the series with VP20, at short hardening times the R\({}_{1}\) values were similar to those of the CEM I series. In spite of that, from about 28 days, the R\({}_{1}\) resistance began to rise to a greater ratio than the series with CEM I, similar to the VP10 series, from 200 days the growth ratio increased markedly as compared with the CEM I series. Figure 8: Percentage of mercury retained at the end of mercury intrusion porosimetry test for the mortars analyzed. Figure 9: Impedance spectroscopy R\({}_{1}\) resistance for the mortars studied. In the case of the R\({}_{2}\) resistance, the resistances associated with the reference series (CEM I) remained practically constant over time; however, the R\({}_{2}\) resistance of the series with VP had a higher growth ratio than the series with CEM I, which was more noticeable beyond 50 curing days. Although both series with VP presented higher values than the CEM I series, the increase in R\({}_{2}\) resistance was much greater in the VP20 series than the VP10 series. At longer ages, the higher resistances noted for the samples with VP could be related to their fine microstructure, which showed a progressive closing of their microstructure, likely linked to the development of pozzolanic reactions, as also shown by the pore distribution size results. In light of this, the results of the R\({}_{1}\) and R\({}_{2}\) resistances would corroborate the pore refinement of the microstructure of mortars with VP, previously observed by mercury intrusion porosimetry, therefore, the the R\({}_{1}\) and R\({}_{2}\) resistances results would be consistent with those noted for pore size distributions and retained Hg at the finish of the test. The results of the C\({}_{1}\) capacitance observed for the CEM I, VP10, and VP20 series are shown in Figure 11. The C\({}_{1}\) capacitance gives data about the solid fraction of the specimens. Therefore, this parameter should rise when the formation of solids occurs as a consequence of the development of clinker hydration and VP pozzolanic reactions. This capacitance is not dependent on the pore diameters distribution. Overall, the C\({}_{1}\) capacitance remained constant after 50 curing days in all the samples studied. The VP10 series showed values very similar to those of the series with CEM I, and their long-term values were slightly higher when VP was used as compared with the samples with CEM I. In the case of the series with VP20, the values were slightly higher than those obtained with VP10 and CEM I. These C\({}_{1}\) results would be in agreement with the relatively similar values of total porosity obtained for all the mortars tested (see Figure 6). The evolution of the C\({}_{2}\) capacitance over time for all the series analyzed is represented in Figure 12. The C\({}_{2}\) capacitance is linked with the surface of the pores which are contacting with the electrolyte held in the pore network of the material and has a relation to the formation of the C-S-H gel layer, which progressively fills the pores [37].