Geosynthetic Applications and Design Methods for Paved and Unpaved Road Systems in Minnesota: Review of Current Practice

Geosynthetics are widely used in pavement systems in multiple applications, including base and subgrade stabilization, reduction of layer intermixing and moisture, and mitigation of shrink/swell-related distresses. However, the current geosynthetic classification system and guidelines employed by the Minnesota Department of Transportation (MnDOT) are predominantly based on product-level test properties rather than on application-specific performance criteria, which are needed for appropriate product selection for effective field implementation. Thus, this study reviews current practices related to field application and design practices of geosynthetics in paved and unpaved roads, especially for MnDOT specifications, guidelines, and design tools. A manufacturer survey revealed that most geosynthetic products are designed for multiple applications, reflecting the feasibility of application-based classification systems. Design methods for both unpaved and paved roads were reviewed, ranging from empirical models to mechanistic-empirical (M-E) approaches and advanced numerical simulations. Although MnDOT recognizes the benefits of geosynthetics, its current design manual and selection guideline do not include clearly defined procedures to quantify these benefits. As regards software, MnDOT’s M-E pavement design tool, MnPAVE, incorporates geosynthetics through equivalent thickness adjustments but does not reflect nonlinear material characterizations or location-dependent behavior. Other tools, including AASHTOWare Pavement M-E software, manufacturer solution methods, and advanced finite-element modeling-based solutions, demonstrate both strengths and limitations in modeling geosynthetic applications for pavements. This paper recommends the adoption of application-based classification in MnDOT specifications and guidelines, the establishment of clearer procedures for quantifying geosynthetic benefits, and the refinement of MnPAVE’s modeling framework to better incorporate geosynthetic behavior based on comprehensive review.