Quantifying the Benefits of Geotextiles and Geogrids for Enhancing Flexible Pavement Performance

Abstract

Constructing with geosynthetics has been shown to improve pavement performance and extend service life. To quantify these benefits, geosynthetic effects need to be consistently modeled in pavement analysis and design. This study compares two mechanistic pavement analysis approaches, MnPAVE and C-FLEX, for designing the same pavement structure, climatic inputs, and traffic loadings. C-FLEX computes pavement responses using finite element analysis considering stress-dependent unbound layer behavior, whereas MnPAVE is based on layered elastic analysis and represents geosynthetic stabilization using an equivalent thickness approach based on Odemark, in which a stiff 1.0-in. sublayer is assigned a product-dependent geosynthetic modulus. In C-FLEX, stabilization is modeled by adjusting the modulus due to an influence zone using enhancement ratios from previously published experimental data. To support a baseline-aligned comparison, the rutting and fatigue cracking transfer-function coefficients were recalibrated for C-FLEX using the non-stabilized cases. Using this framework, both tools generally predict longer service lives for geosynthetic-stabilized sections than for non-stabilized ones. However, MnPAVE predicts larger service life increases in rutting and fatigue cracking, whereas C-FLEX shows clearer product-to-product differences in the predicted response. These differences highlight how modeling assumptions and implementation choices can affect design comparisons and implied maintenance/rehabilitation timing.