## 4 Experimental Setup and Test Program  
A total of 10 full-scale tests were conducted at the construction site of the Osmaniye Governorship, the Special Provincial Administration (SPA) that is located in the north part of Osmaniye, Turkey. The primary objective of this research was to quantitatively assess the performance disparities among geosynthetic products, namely geogrid and \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **Geotextile** & **Geogrid** & **Geocell** \\ \hline Raw Material & Polypropylene + UV & Polypropylene & Polyethylene (HDPE) \\ Unit weight (min. kN/m\({}^{3}\)) & 0.002 & - & 0.094 \\ Thickness (mm) & 1.50 & 3.10 & 1.50 \\ Aperture size (MD/CMD) (mm) & 0.13 (equiviv.) & \(35\times 35\) & - \\ Tensile strength (MD/CD) kN/m & 11–13 & 325 & - \\ Elongation at break strength (MD/CD) & 50–80\% & 90\% & - \\ Puncture Resistance (CBR Test, N) & 2500 & - & - \\ Permeability (m/s) & 0.070 & - & - \\ Dynamic drilling (mm) & 24 & - & - \\ Cell length (mm) & - & - & 300 \\ Cell depth (mm) & - & - & 150 \\ Cell width (mm) & - & - & 250 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Mechanical properties of geosynthetics. Figure 4: The types of geosynthetics: (**a**) geotextile, (**b**) geogrid, (**c**) geocell. geocell, within identical conditions at the experimental test site (SPA). These conditions encompassed identical subgrade strength and base course thickness. Furthermore, an additional experimental section was developed to investigate the impact of the rock fill layer employed as the subbase course layer on the overall performance. The control section, which did not contain geosynthetic materials, was constructed with identical thicknesses of base course aggregate and subgrade strengths. Figure 5 displays the ultimate configuration of the test sections, encompassing the mean subgrade strengths and base thicknesses. The study investigated the effect of reinforcement and rockfill on load-deformation behavior by the repeated plate loading tests in geosynthetic-reinforced and rockfill-stabilized subbase/base layers built on soft clay soil in actual field conditions. For this purpose, excavation was performed approximately 2 m deep, 5.6 m wide, and 25 m long in the previously determined land (SPA). Approximately 1.5 m of clay soil was placed under control, and a plate loading test was carried out on the clay ground. Then, approximately 0.45 m of foundation or sub-base fill layer was built on the clay soil, and repeated plate loading tests were carried out on these sections. In the rockfill test section, approximately 30 cm of rockfill material was placed on soft clay soil. Subsequently, 15 cm of granular filler was placed on it and compacted in a controlled manner (Figure 6). In terms of reflecting soft soil conditions, all test conditions in the field were prepared to be uniform, considering that if the water content of the clay soil placed on the excavation floor is \(26\pm 1\) percent, the CBR value would be between 3-5 percent. A vibratory roller was used to compact the subgrade by making three passes (enough) of the roller for the longitudinal path of the newly placed subgrade. The homogeneity of the soft soil condition was ensured by the water content samples taken from the field and the DCP tests [33]. The test area's upper surface was leveled, and a rigid plate was positioned on a predetermined line to ensure that the loads exerted by the hydraulic jack and loading mechanism, consisting of a vibratory roller with a capacity of 20 tons, would be evenly distributed onto the rigid plate. A hydraulic jack applied a downward force to the vibratory roller. The reaction loading system was subjected to a series of static loads that increased monotonically in each test. The load was applied using a hydraulic jack and maintained manually with a hand pump until the ultimate vertical deformation was obtained. The load and the corresponding plate settlement were measured by a calibrated pressure gauge and two LVDTs, respectively.