ABSTRACT
The strength of pavement materials, stiffness, and subgrade conditions determine paved and unpaved roads in terms of performance and durability. Geosynthetics, especially geogrids, are widely used in stabilizing/reinforcing pavement layers for increasing the modulus of the layer, reducing the construction cost, and increasing the service life. This paper evaluates the layer coefficient ratio (LCR) of extruded polypropylene biaxial geogrid under different subgrade conditions through large-scale cyclic plate load tests. The experiments were conducted based on IRC SP:59-2019 and ASTM D8462-2022 standards and simulated both static and repeated loading conditions. The results showed that geogrid reinforcement significantly enhances pavement performance under repeated loading for both soft and firm subgrades. However, in static loading, geogrids were effective only in softer subgrades, which indicated that the relevance of static testing is limited in evaluating geogrid-stabilized pavements. LCR values increased with geogrid tensile strength, and softer subgrades showed higher values. These results emphasize the importance of geogrid reinforcement in flexible pavement designs, load distribution, surface deformation minimization, and extended pavement life.
