*3.1.2 Analysis of different forms of prepared geopolymer hybrids*

XRD techniques were used for a wide variety of material characterization studies. The XRD results show some qualitative differences in the hydration rate due to the incorporation of PET polymer. **Figure 4** shows the X-ray patterns of the composites with 5% PET and composites without polymer PET (**Figures 3** and **4**). The main compounds observed are large amounts of CaCO3, calcium oxide, and quartz resulting from anhydrous fly ash and sand dune, respectively. The peak intensity in 18, 52 degrees to 67, 37 degrees has been considered a region of the quantity of CaCO3. Therefore, it is also noted here that at a hybrid geopolymer ratio of 5%, a slight increase in the peak intensity compared to the unmodified geopolymer is observed. Furthermore, CaCO3 crystals may produce sharper reflection in the presence of PET polymer due to a change in the orientation pattern of the crystals. Based on SEM micrograph analysis (**Figures 5** and **6**) and chemical composition (**Table 6**), it is possible to explain this variation in terms of the fact that PET addition causes a progressive decrease in the amount of calcium carbonate and calcium

**Figure 4.** *XRD patterns of hybrid geopolymers (GHP-1, GHP-2, GHP-3, and GHP-4) with a NaOH molar ratio variation of 13 M.*

*Structural and Chemical Analysis of New Cement Based on Eggshells and Sand from Dunes… DOI: http://dx.doi.org/10.5772/intechopen.98346*

#### **Figure 5.**

*SEM of the foamed hybrid geopolymer according to the percentage of fly ash eggshell after 1 hour (GPH1, GPH2, GPH3, GPH4).*

#### **Figure 6.**

*SEM of the foamed hybrid geopolymer according to the percentage of fly ash eggshell after 24 hours (GPH1, GPH2, GPH3, GPH4).*


#### **Table 6.**

*Chemical composition of the synthesized hybrid geopolymer (GHP-2).*

oxide in the hybrid composites compared to the unmodified geopolymer. These results agree with previous studies [24].

Images of the SEM micrograph in **Figures 5** and **6** show the microstructure of the mixture hybrid geopolymer based on PET with sand dune (quartz) after 1 hour. The PET composite indicates a weak interfacial transition zone in the hybrid geopolymer matrix interface at 1 hour, which is related to the large shrinkage of the geopolymer paste, as revealed by XRD [25, 26]. There is approximately less distance between PET and the surface of the geopolymer matrix. Furthermore, some microcracks also formed in the hybrid geopolymer. As shown in **Figures 5** and **6**, PET was placed in the crack zone when the specimen was subjected to a chemical reaction after 1 hour. The PET might deform and lengthen, rupture, or pull out because of the applied stress at the fiber section in a crack zone.
