## 3 Results and Discussion
### Field and Laboratory Results Comparison  
The samples extracted from the field layers were also submitted to UCS testing. Figure 9 shows the UCS of the samples recovered from the field after 14 and 120 days and compares these values with those obtained in the laboratory. The field results for mixtures with SHS varied from 850 to 1730 kPa and 220 to 940 without SHS. As is usually the case, the field results are lower than those obtained with the specimens fabricated in the controlled environment of the laboratory. Such difference is more significant after 120 days since the material spent more time exposed to the environment and, thus, was less capable of developing higher UCS levels (when compared with those obtained in the laboratory). Figure 8: Variation in the UCS of the laboratory specimens with curing time. After 14 days of curing, the field /laboratory ratio was 0.80 for the B\({}_{\text{SHS}}\) material and 0.49 for the B\({}_{\text{H2O}}\) material. After 120 days, the same ratio decreased to 0.35 (B\({}_{\text{SHS}}\)) and 0.18 (B\({}_{\text{H2O}}\)), suggesting that the curing conditions (i.e., relative humidity, temperature and precipitation) assumed an important role regarding the production and development of the cementitious gel. In addition to the curing conditions, an important factor to be considered for the UCS results is the difference of the molding process from field to laboratory because, in the laboratory, there is greater control and precision over the molding conditions, such as mixture homogeneity, degree of compaction and guarantee of the shape and measures of the specimen (i.e., vertical sides and flat surfaces), which consequently give better strength results. Moreover, the extraction of the specimens taken from the field sample may have interfered in the results of UCS of the samples recovered the field because, as they were sculpted by hand, the sides and loading surfaces of the specimens were not precisely regular (Figure 4b), which certainly interfered in the strength, negatively. It should also be noticed that the lowest ratios for each curing period were obtained BSHS, which can be interpreted as an indication of higher durability of the alkaline-activated material. Figure 10 shows the monitoring of the climatic conditions to which the stabilized layers were exposed during the curing period. The average temperature was around 15 \({}^{\circ}\)C, therefore lower than the laboratory environment, which most likely hindered the field results. According to the data collected from the weather station, precipitation of approximately 100 mm was registered in the first 14 days of curing, with an increase to 230 mm in the third week. Such high precipitation during the initial and crucial stage of the reactions may have reduced the pH of the pastes and, thus, conditioned the strength development. These climatic conditions, characteristic of the Southern region of Brazil, can significantly influence the field performance, especially of the layers without alkaline activator, which usually show slower development rates than the activated systems. Figure 11 shows the variation in the initial shear modulus (\(G_{0}\)) (average value of three specimens) for the same specimens submitted to the UCS tests. In every case, the \(G_{0}\) increases with increasing curing time. However, the laboratory B\({}_{\text{SHS}}\)/B\({}_{\text{H2O}}\) ratios for samples cured for 14 and 120 days were 2.85 and 2.34, respectively. This difference was even higher for the field-cured material, with ratios of 3.85 and 4.31 after curing periods of  
Figure 9: UCS for field and laboratory samples for curing time of 14 and 120 days. 14 and 120 days, respectively. As expected after the analysis of the UCS results, the field samples showed lower stiffness than the laboratory samples, with lab/field ratios of 2.58 (14d) and 2.39 (120d) for the B\({}_{\rm H2O}\) material, and 1.70 (14d) and 1.44 (120d) for the B\({}_{\rm SHS}\) material.