## 3 Results and Discussion
### Non-Destructive Tests
#### 3.2.3 Discussion of the Tests Results  
By assessing the non-destructive test results, it was possible to compare the mechanical properties of the developed mortars. In addition, it allowed for the evaluation of the binder and aggregate influence and the addition of nano and micro silica particles.  
Figure 8 presents the correlation between the velocities and frequencies and the content of the binder for each composition. As shown in Figure 8, the results obtained from the non-destructive tests show that the velocities/frequencies increase as the binder content increases. Analysing the results of the mortars developed in the laboratory, V has the highest amount of binder, and it has the highest values of velocities and frequencies, while P.NMS has the lowest values.  
Comparing the values of velocities and frequencies between EP and EV when increasing 1% of binder in the composition, V showed a 6.4% average increase in its properties compared to V.NMS.  
However, no considerable differences were observed between P and P.NMS. P and P.NMS had results within a similar range of values, and V had _Vp_, _Vs_, \(f_{f}\) and \(f_{t}\) only 5%, 3%, 10% and 8% higher than V.NMS', respectively.  
Table 4 shows the average property values for each mortar from the UPV and IEV tests.  
The Poisson's ratio directly influences the compression and flexural strengths, as it is proportional to Young's modulus and the shear modulus (Equation (6)).  
The Poisson's ratio values presented in Table 4 vary between 0.18 and 0.23, and agree with the values presented by different authors [23; 24], in which the Poisson's ratio values vary between 0.19 and 0.34. Still, in Table 4, it can be seen that the V and V.NMS groups had the highest range of average values of E and G.  
Figure 8: UPV velocities (m/s) and IEV (Hz) frequencies as functions of binder content.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Mortar Designation** & \(f_{f}\) (Hz)** & \(f_{f}\) (Hz)** & **E (GPa)** & **G (GPa)** & _μ_ \\ \hline C & 972 & 1114 & 2.601 & 1.091 & 0.19 \\ P & 667 & 756 & 1.381 & 0.564 & 0.22 \\ P.NMS & 666 & 755 & 1.293 & 0.533 & 0.21 \\ V & 950 & 1077 & 2.721 & 1.111 & 0.22 \\ V.NMS & 867 & 999 & 2.708 & 1.118 & 0.20 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Impulse excitation of vibration test results.  
V stands out as the composition with the highest mechanical properties values as its Young's modulus was 119%, 125% and 5% higher than P.NMS, P and V.NMS values, respectively, and its shear modulus was 121%, 127% and 4% higher, respectively.  
The average values of E and G presented in Table 5 are in accordance with the literature review [21; 23; 24], with E values between 1.573-4.28 GPa and G values between 0.655-1.205 GPa.  
As verified by the results obtained in the non-destructive tests, in which the velocities/frequencies increase as the binder content increases (Figure 8), the mechanical properties (E and G) also increase as the binder content increases. Table 5 summarises the relationship between the mechanical parameters of the developed mortars and the commercial composition.  
The assessment of Table 5 allowed us to conclude that the developed mortars showed two distinct characteristics: (i) the P and P.NMS groups have E and G average values in the range of 50% lower than the commercial composition, and (ii) the V and V.NMS groups show clearly enhanced E and G average values when compared to C's. The enhanced results of the V and V.NMS groups are due to the use of 75% and 74% binder content, respectively. Establishing a linear regression between the average values of E and G reveals a strong correlation, as evidenced by a [PERSON]'s correlation coefficient of 0.9992. This correlation implies that compositions V, V.NMS, C, P.NMS, and P are likely to show the highest compressive and flexural strength values, respectively.