Refined Approach to Evaluate the Modulus of Geosynthetic Reinforced Flexible Pavements

Abstract

The road infrastructure of any nation is a key component of its infrastructure and its economy. Flexible pavements are the dominant portion of the road infrastructure in India and utilize vast natural resources in construction. Given the scarcity of natural resources, there is a pressing need for innovative solutions to reduce their consumption. In this context, geosynthetics, particularly geogrids, are recognized for their potential to enhance the sustainability of flexible pavements by reducing the reliance on natural materials. However, the proper implementation of geogrids in pavement design remains a challenge, with key factors like the modulus influencing performance. Current literature often calculates the modulus of the reinforced layer by considering that the entire layer is affected by reinforcement, leading to overestimated modulus values. Hence, an effective approach was developed to accurately apply the modulus improvement only to the geogrid’s influence zone within the geogrid reinforced layer. The analysis compared the unreinforced flexible pavement, geogrid reinforced flexible pavement (GRFP), and modified GRFP designs, mainly focusing on optimizing the layer thicknesses. Additionally, this study includes a cost comparison of GRFP and modified GRFP with unreinforced flexible pavement design. The GRFP design, based on the existing procedure, reduced the combined total thickness of asphalt and WMM layers by 14%, along with a 24% cost saving compared to the unreinforced section. In contrast, the modified GRFP approach yielded a slightly lower thickness reduction of 12% within the reinforced layer and a modest cost saving of 0.11%. A preliminary life-cycle cost analysis (LCCA) was also done for maintenance and repair costs in order to comprehend long-term economic benefits. LCCA also supports the presented approach by achieving considerable cost savings in comparison to the unreinforced section. Beyond these economic gains, the proposed approach provides a more accurate design methodology aligned with realistic reinforcement behaviour, highlighting the long-term structural and economic benefits of geosynthetic applications in flexible pavement construction. © The Author(s), under exclusive licence to Indian Geotechnical Society 2025.