Geotextiles and geogrids have been used in pavement applications for decades, but quantifying their benefits in a way that supports routine design decisions has remained challenging. A major research initiative led by the Minnesota Department of Transportation (MnDOT) in partnership with Iowa State University and the University of Illinois at Urbana-Champaign aims to change that .
The Research Initiative
The project, titled "Quantify the Benefits of Using Geotextiles and Geogrids to Improve the Performance of Unbound Pavement Layers," brings together leading researchers from multiple institutions :
Principal Investigator:
Erol Tutumluer, Professor, University of Illinois at Urbana-Champaign
Co-Principal Investigators:
Halil Ceylan, Director, PROSPER, Iowa State University
Sunghwan Kim, Associate Director, PROSPER, Iowa State University
Issam Qamhia, Research Scientist, University of Illinois at Urbana-Champaign
Sponsor: Minnesota Department of Transportation (MnDOT)
Partners: University of Illinois at Urbana-Champaign (as Lead)
Why This Research Matters
Geotextiles and geogrids are the most used geosynthetics in transportation and pavement applications, yet design guidance has often lagged practice. Many transportation agencies have developed local guidelines based on field experience rather than systematic quantification of benefits .
This research addresses that gap by providing a current best practices design guide for road designers detailing when to use and what types of geotextiles and geogrids to use for given soil, pavement designs, and traffic conditions .
Key Functions Being Studied
The research recognizes that geotextiles and geogrids serve distinct but complementary functions in pavement systems :
Layer intermixing reduction: Preventing contamination of aggregate base by subgrade fines
Moisture reduction: Facilitating drainage and maintaining optimal moisture conditions
Confinement and stabilization: Providing lateral restraint to aggregate and subgrade materials
Geogrid Functions:
Mechanical stabilization: Providing strength to base and full depth reclamation material through lateral restraint
Improved load-bearing capacity: Distributing loads across wider areas in pavement systems
Research Objectives
The main objective of the study is to produce a current best practices design guide for road designers detailing when to use and what types of geotextiles and geogrids to use for given soil, pavement designs, and traffic conditions. Having a guide will aid designers in utilizing these products to better predict pavement outcomes and to extend pavement life .
Specific project tasks include :
Evaluating current MnDOT practice related to the beneficial and cost-effective use of geosynthetics
Reviewing research and state of the practice on geosynthetics applications, available products, design methods, and specifications
Proposing recommendations for geosynthetic solutions in pavements to modernize MnDOT's practices and manuals
Expected Outcomes
The study will highlight current best practices and produce two key deliverables :
1. A synthesis report documenting the state of knowledge on geosynthetic applications in pavements
2. A Technical Guide for using geotextiles and geogrids based upon:
Soil type
Pavement structure
Traffic loads
This will include quantification of benefits based on the functions of the geotextile—separation, filtration, drainage, and stiffening or stabilization—and for geogrids, stabilization of aggregate cover over soft subgrade in unpaved roads and paved road unbound aggregate layer stabilization .
Quantification of Benefits
A key innovation of this research is the quantification of geosynthetic benefits. The Technical Guide will include :
Strength gain quantification: For base or full depth reclamation material when reinforced with geogrids
Performance prediction: Allowing designers to better predict pavement outcomes
Life extension estimates: Quantifying how geosynthetics extend pavement life
Practical Implications for Pavement Designers
Once completed, this research will provide pavement engineers with :
1. Clear decision criteria: When to use geotextiles versus geogrids versus combinations
2. Material selection guidance: What types of geosynthetics work best for specific soil conditions
3. Design quantification: Numeric values for benefit estimation, enabling rational design
4. Lifecycle economic analysis: Tools to evaluate cost-effectiveness of geosynthetic inclusion
The Broader Context
This MnDOT initiative is part of a broader movement toward performance-based specifications and lifecycle design in transportation infrastructure. By quantifying the benefits of geosynthetics, the research will enable :
More widespread adoption of proven technologies
More accurate pavement design
Better allocation of infrastructure funding
Extended pavement service life
Conclusion
The MnDOT research initiative represents a significant step forward in quantifying the benefits of geotextiles and geogrids in pavement applications. By producing a current best practices design guide based on rigorous research, the project will enable road designers to make informed decisions about when and how to use these materials to extend pavement life and optimize infrastructure investments .
At HZ Geotextile, we follow research developments closely to ensure our products align with the latest design guidance. Contact our team for assistance with geosynthetic selection for your pavement projects.
