## 3 Results and Discussion
### Microstructural Characteristics
#### 3.3.2 XRD Analysis
teristics, as observed in previous research studies on cementitious composites [22; 92]. The XRD analysis (Figure 17) also revealed the formation of magnesium-aluminum hydotalcite (Mg\({}_{6}\)Al\({}_{2}\)(OH)\({}_{16}\)CO\({}_{3}\)-4H\({}_{2}\)O)-like phases due to the reaction of MgO with the slag in addition to C-S-H, as confirmed from previous studies by [PERSON] et al. (2011) [55] on the effect of natural MgO on alkali-activated slag. The content of these hydotalcite (Ht or L')-like phases increases with the dosage of MgO and is more voluminous than that of C-S-H, which results in a higher strength (as observed in the current study) and the long-term stabilization of polymers, leading to excellent performance. In general, MgO hydrolyzed on the surface either reacts with the broken Si-O or Al-O to form magnesium silicate hydrate (M-S-H) or Ht, hindering the precipitation of brucite. These findings are also confirmed by early studies that found that Mg is quickly consumed to form Ht or M-S-H in combination with silica fume or slag [93; 94], although M-S-H is hard to detect with XRD [95]. For the MWCNT-incorporated AAEC mix B2C6, the highest peak representing quartz (E') is identified at 26.43\({}^{\circ}\) 20 (Figure 19), and the highest peak for quartz (E') and penta barium tetra niobium oxide (V') is identified at 26.43\({}^{\circ}\) and 29.43\({}^{\circ}\) 20, respectively, for the rGO-incorporated mix B2R6 (Figure 20). The dominant element phase consisting of oxygen, and silicon was observed for both mixes. In previous studies, XRD analysis demonstrated an increase in the amorphous phase, C-S-H, and geopolymerization with the addition of MWCNTs, exhibiting a dense matrix with a lower content of unreacted  
Figure 18: XRD diffractograms of (**a**) B2M5 and (**b**) T2M5. fly ash particles and an increase in the compressive strength (low dosages of 0.3% as observed) [41]. However, no influence of MWCNTs on the reaction products of AAECs has been observed via XRD even though MWCNTs can act as nucleation sites and accelerate polymerization, similar to the effects observed in previous studies [35; 38; 42]. This can be attributed to the minimal dosages of MWCNTs which cannot effectively be detected and the hindrance of deep and quantitative analyses due to the highly amorphous characteristics of geopolymer with coexisting terpolymeric gel (three-component monomer gel) and partially reacted or unreacted precursors. More advanced technologies are then required for further investigation. The introduction of rGO leads to an increase in the peak intensity of quartz (E') and zeolites within the geopolymer, representing the development of crystalline phases. FA/GGBFS compositions predominantly comprise amorphous glassy microspheres and crystalline quartz, mullite, and haturite. Geopolymerization is the process of dissolving the glassy phase of source materials (FA or GGBFS) in an alkaline solution to form geopolymer gels. rGO acts as a catalyst to accelerate electron/mass transfer during alkali-activation reaction and promotes the dissolution of amorphous phases of FA/GGBFS microspheres by transmitting free electrons. rGO promotes the transformation of [SiO\({}_{2}\)(OH)\({}_{2}\)]\({}_{2}\) and Al(OH)\({}_{4}\) to the AlSiO\({}_{4}\) or AlSi\({}_{3}\)O\({}_{8}\) structure and accelerates the growth of geopolymer gels [96] to produce zeolite crystals with a higher diff  
Figure 19: XRD analysis of MWCNT incorporated AAEC (B2C6). Figure 20: XRD analysis of rGO-incorporated AAEC (B2R6).