## 6 Conclusions  
To assess the potential advantages of utilizing geosynthetic-reinforced or rock-stabilized granular fill layers constructed above natural clay deposits for unpaved roads, a series of 10 full-scale model repeated plate loading tests was carried out. The findings of this investigation led to the following primary conclusions.  
For all sections, after traffic passage (N\({}_{\text{traffic}}\) = 5000), repeated plate loading test results showed that deformation values decreased by 60-70% compared to before traffic passage. The best performance was obtained in the rock fill section. Furthermore, it has been observed that geosynthetic sections show a performance close to the rock-filled section. Among the sections reinforced with geosynthetics, the best performance was obtained using geocell.  
Repeated plate loading experiments performed after traffic loading were used to determine the total and permanent displacements of the sections. The best performance in total and permanent displacements was obtained in sections stabilized with rock fill and reinforced with geocell. It is considered that the section reinforced with geocell performs better than those of geogrid because of the better lateral confinement of geocell granular material, especially after traffic loads. The findings showed that there was also a significant  
Figure 12: The effect of NPLT on the modulus improvement ratio (MIR): (**a**) N\({}_{\text{PLT}}\) = 1, (**b**) N\({}_{\text{PLT}}\) = 1,2,5.  
increase in the elasticity modulus in the sections reinforced with geosynthetics as the plate loading number increased (N\({}_{\text{PLT}}\) = 1-2-5). It was observed that as the number of repetitions increased in the repeated plate loading tests, the increase in the elasticity modulus improvement ratio (MIR) was even greater. As a result of the fifth repeated plate loading test (N\({}_{\text{PLT}}\) = 5), the MIR value was approximately 85% for the section improved with rock filling, while this rate was 48% for the section reinforced with geocell. Additionally, in the test sections reinforced with geogrid, the MIR value was obtained as approximately 12% for single geogrid and 28% for double geogrid.  
While the best performance in elastic modulus was seen in rock fill, the same increase was not observed in the unreinforced (granular fill) section. In fact, the results indicated that the rock fill layer spreads the applied load over a larger area, reducing displacements and, therefore, having a higher modulus of elasticity.  
The results of the repeated PLT on the unpaved test sections demonstrate the benefits of using geosynthetics in reducing the permanent deformation in the road structure. This evaluation proves that geosynthetics can be an alternative to rock fill, as quality materials such as those used for rock filling are rapidly depleting worldwide, and the cost of this material constantly increases. The investigation is considered to have provided a valuable basis for further research, leading to a better understanding of the benefits of using geosynthetics in reducing permanent deformation on unpaved roads. On the other hand, the findings offer valuable insights for road construction on soft subgrades. The results on the geosynthetics reinforcement and rock fill stabilization provide alternative application methods for engineering practice, considering the cost and environmental impact.