Large-Scale Laboratory Testing of Geosynthetics in Roadway Applications

Monday, April 12, 2021 - 17:30

This project studied the performance of geotextile-reinforced test sections when compared to an unreinforced case to assess benefit in terms of an extension of the life of the pavement. A single test track was constructed in an indoor test facility and contained two test sections with a reinforcement geotextile (woven and non-woven) while the third section was unreinforced. The test sections constructed had a nominal section of 3.4 inch of hot mix asphalt and 13.3 inch of base course aggregate on a clay subgrade with a constructed CBR of 3.5. The test sections were trafficked by a full-scale accelerated pavement tester with approximately 1 million traffic passes applied. The raw rutting results showed the unreinforced test section to perform better than the two sections with a geotextile. An analysis of the data showed that the three test sections performed similarly in terms of rutting performance for the conditions present in this study. The spreadsheet design model developed previously for MDT by the PI using reasonable input parameters predicted little reinforcement benefit for these conditions. This model showed moderate reinforcement benefit for weaker subgrade conditions that might be present in typical Montana roadways during seasonally wetter periods. This study did not quantify the separation benefit of the geotextiles, which are a recognized benefit applicable to most roadways in the state. A cost analysis showed the cost of the woven and non-woven geotextiles was approximately 13 and 6.5 % of the total roadway material cost, respectively. The benefit associated with this cost lies in the geotextile’s function as a separator, which may reduce the cost of rehabilitation and reconstruction operations and to ensure the structural performance of the pavement during seasonal periods where the subgrade may become wet and weak. The full report is available online from the Montana Department of Transportation at