## 3 Results and Discussion  
### Complementary Tests  
The density and porosity test results are shown in Figure 3. Notable variations between the densities were observed. The commercial solution had the lowest density, about 7%, 10%, 21% and 17% lower than P, P.NMS, V and V.NMS, respectively. The differences in densities between the developed mortars were due to two factors: (i) EV has a higher apparent density than EP because they have maximum values of 192 kg/m\({}^{3}\)[32] and 100 kg/m\({}^{3}\)[33], respectively, and (ii) different amounts of binder in the compositions. Figure 3: Average composition: (**a**) density and (**b**) porosity. Figure 2: Schematic representation of the experimental test setup for both destructive tests: (**a**) machine “SHIMADZU”; (**b.i**) flexural test support system, (**b.ii**) compression test support system, (**c**) load cell; (**d**) computer, (**e.i**) flexural and (**e.ii**) compression test specimens and, (**f.i**) flexural and (**f.ii**) compression support system representation. Concerning the porosity rates, mortar C stands out as the one having the highest porosity, about 51%, 60%, 30% and 24% higher than those of P, P.NMS, V and V.NMS, respectively. The sizes of EP and EV particles led to a notable difference in the mortars' porosities. As shown in Table 1, about 50% of EP particles have a size of 0.090 mm, while about 65% of EV's have a size between 1.400 and 1.000 mm; thus, the P and P.NMS groups present the lowest values of porosity. From the MIP tests, as used in other scientific studies [34; 35; 36], it was possible to evaluate the pore size distribution and dimensions in gypsum matrices with different compositions (Figure 4). In this study, it was observed that the peak of the pore size distribution curve was very similar for the compositions P, P.NMS, and VNMS (approximately 4200 nm). In contrast, the commercial composition exhibited a peak around 2500 nm, while composition V showed two distinct peaks, one at 3000 nm and another at 18,000 nm. It is also noted that the micro and nano silica had a favourable effect on composition V, as it eliminated one of the peaks, contributing to a more homogeneous pore distribution. The mass loss with increasing temperature was analysed by TGA (Figure 5). Only commercial solutions and compositions with the best thermal behaviour (P.NMS) [9] were tested. Figure 4: MIP testing result curves (V denotes the intruded mercury or pore volume and d denotes the calculated equivalent pore diameter). Figure 5: TGA data of C and P.NMS compositions. The TGA curves are similar, with two clearly separated mass-loss steps, although a difference in the magnitude of mass loss is observed. Based on the sample composition, between 100 and 250 \({}^{\circ}\)C, two-step dehydration of calcium sulphate dihydrate occurs, while above 600 \({}^{\circ}\)C, the decomposition of calcium carbonate takes place (CaCO\({}_{3}\)\(\rightarrow\) CaO + CO\({}_{2}\)). Gypsum dehydration generally occurs within the temperature range of 80-250 \({}^{\circ}\)C, depending on the heating rate and composition of the gypsum. This process occurs in two stages: (i) the first dehydration occurs between 80 and 150 \({}^{\circ}\)C (CaSO\({}_{4}\).2H\({}_{2}\)O \(\rightarrow\) CaSO\({}_{4}\).1/2H\({}_{2}\)O), and (ii) the second, complete dehydration occurs (CaSO\({}_{4}\).1/2H\({}_{2}\)O \(\rightarrow\) CaSO\({}_{4}\)) between 150 and 250 \({}^{\circ}\)C [37; 38; 39]. PNNMS lost 10.4% and 15.5% of its initial weight at 170 \({}^{\circ}\)C and 1000 \({}^{\circ}\)C, respectively, while C lost 15.9% and 22.8% at 170 \({}^{\circ}\)C and 1000 \({}^{\circ}\)C, respectively. The XRD test was carried out to better understand the crystalline phases of the commercial and P.MNS compositions, and the results are shown in Figure 6.  
By assessing XRD and TGA results, it was determined that the commercial composition is made mainly from gypsum, about 70%, with the remaining 30% being EP, EV and other  
Figure 6: XRD test results for (**a**) commercial and (**b**) P.MNS compositions.