## 3 Materials and Methods
### Green Material Characterization
#### 3.6.2 XRD Analysis  
To evaluate the changes in the mineralogical characteristics of the contaminated soils, selected samples were analyzed by X-ray diffraction (XRD) using the Rigaku Miniflex 600 X-ray diffractometer (Tokyo, Japan). The results of the analysis, including the diffractogram and the mineralogical components detected in MSWI-FA, W-FA, GGBFS, MS, and CEM, are presented in Figure 7 below.  
The XRD spectra of MSWI-FA show the presence of crystalline species containing calcium, such as lime (CaO), calcite (CaCO\({}_{3}\)), portlandite (Ca(OH)\({}_{2}\)), and calcium sulfate (CaSO\({}_{4}\)), and phases containing chlorine, such as sodium chloride (NaCl), potassium chloride (NaCl), and calcium sulfate (CaSO\({}_{4}\)). The results of the analysis are presented in Figure 7.  
Figure 7: XRD analysis results, diffractogram and mineralogical components detected in (**a**) MSWI-FA, (**b**) W-FA, (**c**) GGBFS, (**d**) MS, and (**e**) CEM.  
-ride (KCI), and calcium chloride hydroxide (CaCIOH). The identification of these crystalline species reinforces the EDS chemical analysis, where a high percentage of calcium and chlorine relative to other elements is found. Another crystalline species easily distinguishable in the diffraction spectrum is SiO\({}_{2}\).  
The XRD data of W-FA showed the presence of crystalline phases similar to those of MSWI-FA, as well as additional hydrated crystalline species containing calcium, such as singenite (K\({}_{2}\)Ca(SO\({}_{4}\))\({}_{2}\cdot\)H\({}_{2}\)O), gypsum (CaSO\({}_{4}\cdot 2\)H\({}_{2}\)O), and calcium chloride dehydrate (Ca(CIO)\({}_{2}\cdot\)3H\({}_{2}\)O). The presence of these latter mineralogical phases is justifiable given the pretreatment of the ashes, carried out through water washing. Another noticeable difference from the mineralogical analysis of untreated fly ashes and treated ones is that the latter contain fewer crystalline phases containing chlorine (NaCl). The XRD results are consistent with the EDS analysis, as after washing pretreatment, a significant decrease in chloride content was observed in W-FA. The results of the XRD analysis of CEM show that the main crystalline phases are alite (Ca\({}_{3}\)SiO\({}_{5}\)) and belite (Ca\({}_{2}\)SiO\({}_{4}\)). There are additional crystalline phases containing aluminum, such as brownmillerite, sodium aluminum, and calcium aluminum. In particular, alite (Ca\({}_{3}\)SiO\({}_{5}\)) gives the material early strength development, followed by belite (Ca\({}_{2}\)SiO\({}_{4}\)), which performs a similar function to alite but acts over the long term. Moreover, these calcium silicates, reacting with water, form portlandite, a crystalline phase (Ca(OH)\({}_{2}\)), and an amorphous calcium silicate hydrate phase, commonly known as CSH, responsible for hardening.  
To ensure the principle of identity for the mineralogical components, granulated blast furnace slag (GGBFS), a by-product of the iron industry, was also analyzed using the X-ray diffraction (XRD) method. The mineral phases present in GGBFS are wustite (FeO), monticellite, and gehlenite. Finally, the crystalline phases present in marble sludge are quartz, calcite, and an nite.