## 3 Results
### XRD Analyses
Figure 6: TQ5 diffractogram at day 0 (blue) overlaid on that of TQ0 (red). The most significant changes are related to three angular positions: 20 = 17.7856\({}^{\circ}\) (peak magnification), 20 = 34.9596\({}^{\circ}\) (peak magnification to the left), and 20 = 26.7273\({}^{\circ}\) (peak intensity reduction). These results demonstrate that the added quicklime caused positive results: Peak intensity reduction produced by clay minerals and changes in the 20 range between 20\({}^{\circ}\) and 35\({}^{\circ}\), which is the typical diffraction range of CASH [38]. It demonstrates the on-going process of the lithosynthesis process: After 7 d curing, new aggregate structures are present in the treated soil. Figure 8 shows the X-ray diffraction pattern of the 7 d mellowed TQ5 (blue curve) overlaid on the diffractogram of TQ (red curve) (Figure 2). The green circles in Figure 8 highlight the changes observed at day 7 in TQ3 (Figure 7): In TQ5, the differences regarding higher or lower peak intensity are higher than those in TQ3. Moreover, in Figure 8, the blue circles highlight the new variations. Three main changes are identifiable:  
* 20 = 17.7856\({}^{\circ}\) shows a local enlargement of the diffraction peak;
* at 20 = 34.9596\({}^{\circ}\), the peak height is slowly reduced and is shifted toward lower diffraction angles. This modification indicates the presence of traces of Portlandite;
* at 20 = 26.7273\({}^{\circ}\), the peak height is reduced. Therefore, the added quicklime modified TQ0 at the 7 d mellowing period because the observed modifications involve a reduction of clayey minerals (i.e., reduced peak of I at 20 = 26.7273\({}^{\circ}\)) and the  
Figure 8: Overlay of 7 d TQ5 diffractogram (red) and TQ0 diffractogram (blue). Figure 7: Overlay of TQ3 diffractogram at day 7 (red) and TQ0 diffractogram (blue). observed peaks are between 20 = 20\({}^{\circ}\) and 35\({}^{\circ}\). This range is typical of CASH, from which both CSH and CAH are derived. CSH and CAH are reaction products with needle-like structures that provide strength to the material and guarantee the connection between the clay particles. The overlay of XRD patterns of TQ0 (Figure 2) and TQ3 at the 28 d mellowing period is shown in Figure 2:0  
It is possible to verify that the changes observed at 7 d have continued over time. With regard to the 7 d XRD pattern of TQ3 (Figure 7), the main changes are:  
* at 20 = 17.7856\({}^{\circ}\), the peak height is greater;
* at 20 = 34.9596\({}^{\circ}\), the peak is widened;
* at 20 = 26.7273\({}^{\circ}\), the peak height is still reduced. The three typical diffraction peaks of calcite (20 = 43\({}^{\circ}\), 47\({}^{\circ}\), and 48\({}^{\circ}\)) are highlighted in blue: In TQ3, they show greater intensity than those in the TQ0 diffractogram (Figure 2). This is due to the carbonation of the added CaO caused by the chemical reaction with CO\({}_{2}\) (Equation (1)): The reaction product CaCO\({}_{3}\) binds the soil grains. Figure 2:1  
At the 28 d treatment period, TQ5 had the X-ray diffraction pattern shown in Figure 10 (red curve); the blue curve in Figure 10 refers to TQ0. Figure 2:2 Overlay of TQ5 diffractogram at 28 d (red) and TQ0 diffractogram (blue). Figure 2:3 Overlay of TQ3 diffractogram at 28 d (red) and TQ0 diffractogram (blue). However, the observed changes in Figure 10 are not related to new formations: The high percentage of quartz in TQ0 slows down reactions between soil and lime and inhibits the total crystallization of CASH into CSH and CAH. Moreover, the presence of calcite, both natural and resulting from the carbonation of calcium, cannot be overlooked. It can form comparatively weak cementing agents such as calcium carbonate, and this reaction is undesirable because it exhausts some lime that would normally be used to form more resistant cementitious products [39; 40].