## 3 Results and Discussion
### Spread Footing Testing  
Figure 12 shows the load vs. settlement results of the plate tests performed on the seven field layers. The loading capacity of the natural soil, which was used as a reference in the present study, was determined by [11]. The stabilization produced an initial strength increase relative to the response of the natural soil.  
For better observation of the general trends verified in the two diameters used, the applied loads and the respective settlements were normalized by the area, and the resulting stress was then plotted as a function of the relative settlement (\(\delta\)/\(Dr\)). Figure 13 shows that,  
Figure 12: Load vs. settlement (**a**) Cured for 14 days; (**b**) Cured for 120 days.  
after normalization, most curves are approximately superimposed, including that from the natural soil. The representation of the normalized results thus suggests that, regarding the D\({}_{\text{r}}\) 450 mm tests, failure was controlled by the load capacity of the soil underlying the stabilized layer. As the load increases, there is a progressive breaking of the bonds of the weakly cemented residual soil supporting the stabilized layers, resulting in the vertical penetration of the foundation with practically no lateral movement of the soil. This behavior is typically observed when structured soils lose their fabric [54]. The D\({}_{\text{r}}\) 900 mm layers reached the failure before the load capacity of the natural soil was exceeded (note that this capacity is higher than that of the foundation soil of the D\({}_{\text{r}}\) 450 mm layers), which justifies that the overlapping of the normalized 900 mm curves with the normalized 450 mm curves occurs only for an initial relative deformation of approximately 0.1%.  
In general, there was a proportionality between the load capacity and the reinforced diameter--for the same load, lower displacements were observed for the higher diameter. However, the failure mechanism was different for each diameter. For the smaller diameter (D\({}_{\text{r}}\)450B\({}_{\text{SHS}}\) and D\({}_{\text{r}}\)450B\({}_{\text{H2O}}\)), a puncture failure mechanism occurred when the steel plate and the stabilized layer underneath behaved as a single element and penetrated the soil without any lateral movement. This mechanism was fully observed during the analysis of the exhumed layers when it became clear the soil penetration without any visible cracks (Figure 14).  
Figure 13: Normalization of results.  
The larger diameters (D\({}_{\text{r}}\)900B\({}_{\text{SHS}}\) and D\({}_{\text{r}}\)900B\({}_{\text{H2O}}\)) showed a different failure mode, characterized by punching shear, which resulted in the clear separation of a cylinder located beneath the circular plate from the remaining body of the stabilized layers (Figure 15). Some tension cracks were also formed inside the cylinder when it tried to expand laterally due to the [PERSON]'s effect. Additionally, two or three radial cracks developed from the center to the edges. Similar failure modes and cracking patterns were found by [11; 24], soil stabilized with Portland cement.  
Figure 14: D\({}_{\text{r}}\) 450 mm B\({}_{\text{SHS}}\) stabilized layer exhumed from the soil.