Performance of Flexible Pavement Using Biaxial Geogrids: A Mechanistic Approach Using IITPAVE Software
Abstract
Flexible pavements under heavy traffic must control fatigue cracking in the bituminous layer and permanent deformation in the subgrade. This study examines whether biaxial geogrid reinforcement can reduce pavement thickness for a design traffic of 175 million standard axles (msa), 9% subgrade CBR and 90% reliability.The biaxial geogrids were considered at the Base/WMM–GSB and GSB–Subgrade interfaces. A conventional section was first selected using IRC:37-2018 and checked in IITPAVE. Two reinforced alternatives were then prepared. In the Layer Coefficient Ratio (LCR) method, geogrid benefit was applied to the granular layer coefficients following the adopted design approach. In the Modulus Improvement Factor (MIF) method, the same numerical factors were applied to resilient modulus for comparison. AASHTO relationships were used to connect resilient modulus and structural layer coefficient, and IITPAVE was used to check tangential tensile strain at the bottom of the bituminous layer and vertical compressive strain at the top of the subgrade. The final unreinforced pavement was 630 mm thick. The LCR section was 480 mm thick, saving 150 mm, while the MIF section was 555 mm thick, saving 75 mm. All three final sections satisfied the adopted fatigue and rutting limits. The study shows that biaxial geogrid can reduce granular material demand, but the calculated saving depends on how reinforcement is represented in design