## 3 Results and Discussion
### Microstructural Characteristics
#### 3.3.2 XRD Analysis  
The XRD patterns of the representative control binary/ternary mixes incorporating reagents 1 and 2 (B1, T1 and T2) are illustrated in Figure 17a,b. A mix of peaks and broad humps can be identified in the diffractograms for the binary and ternary mixes, signifying a combination of reaction products composed of crystalline and amorphous phases. For instance, the peak at 36.7\({}^{\circ}\) 20 for all compositions consisted of multiple minerals (quartz, wadalite, gehlenite, hydrotalcite, and gypsum). The dominant crystalline phases of quartz (Q or E') were seen for all the mix compositions, with the highest peak being seen at about 26.7\({}^{\circ}\) 20. The sharpest and highest intensity peak for the quartz phase was observed in the T2 diffractogram (indicating a dominant crystalline binding phase), which had more peaks than its counterparts (T1) and other binary (B1) mixes with reagent 1. Also, portlandite (calcium hydroxide) can be seen around 34.2\({}^{\circ}\) 20 in the ternary mix T2 diffractogram because of the composition of reagent 2 and is responsible for forming additional binding phases. This peak characterization is consistent with the previous investigations on fly ash/slag binder [90]. The primary binding phases consisted of C-A-S-H and calcium-rich N-C-A-S-H for the binary mixes. In the ternary mixes, C-A-S-H and N-C-A-S-H were observed for the mixes with reagent 1, and a blend of N-A-S-H and N-C-A-S-H was identified with traces of C-S-H for the mixes with the reagent 2. The presence of these acute phases in the XRD analysis validated the SEM/EDS analysis of the binary and ternary mixes. Small reflections of ettrinigite were seen for ternary mix T2, with its maximum peak at 15.5\({}^{\circ}\) 20, as presented in Figure 18b. Traces of gypsum and periclase (MgO) were also determined in all compositions. The presence of gypsum prevented the flash setting of these mixes. The MgO content in the mixes is known to reduce shrinkage and facilitate the self-healing behavior of cementitious composites due to its inherent expansive characteristics. Figure 18 shows the material compositions and phase compositions of the B2M5 and T2M5 mixes. The dominant crystalline phases of quartz (E') were seen for all compositions. The highest peak, representing calcite, quartz, and periclase (p'), for B2M5 was identified at 29.54\({}^{\circ}\) 20, (Figure 18a). In contrast, quartz and periclase (MgO or P') showed the highest peak for T2M5 at 27.11\({}^{\circ}\) and 29.49\({}^{\circ}\) 20 (Figure 18b). Both mixes exhibited a dominant element phase consisting of oxygen, carbon, and silicon. They exhibited domination crestline products of calcium carbonate and silicon oxide, which enhanced the compressive strength of the MgO-incorporated AAECs (Figure 11a). The XRD analysis of T2M5 (Figure 18b) shows a 45% crestline product of tris boroxine and 25.5% silicon oxide, which help to enhance the compressive strength, and the peak count was identified at 27.11\({}^{\circ}\) and 29.49\({}^{\circ}\) 20. This peak characterization is consistent with the previous investigations on fly ash/slag mixes [91]. MgO impacted the XRD pattern of the AAECs, and the presence of MgO can lead to the formation of magnesium silicate phases such as forsterite (Mg\({}_{2}\)SiO\({}_{4}\)) and enstatite (MgSiO\({}_{3}\)), which can be identified by their characteristic peaks in the XRD pattern. The traces of gypsum and periclase were also found in all compositions. The XRD pattern also confirms the previous SEM/EDS result shown in Figure 16c,d. It is expected that the presence of gypsum will prevent the flash setting and MgO is expected to reduce shrinkage and facilitate the self-healing behavior of the AAECs due to its inherent expansive charac  
Figure 17: XRD diffractograms: (**a**) B1, (**b**) T1 and T2; (**Q—quartz,** G—gypsum,** E—ettringite,** G\({}_{\rm e}\)—gehlenite, P\({}_{\rm o}\)—portlandite, P—periclase, H—hydrotalcite, C—calcite, W—wadalite) [61].