As described in the final report, full-scale test sections were constructed, trafficked and monitored to compare the relative operational performance of geosynthetics used as subgrade stabilization as well as determine which material properties are most related to performance. Seventeen, 50-ft. long test sections were constructed – fourteen containing geosynthetic reinforcement and three without. A subgrade material was prepared and constructed to an average strength of 1.79 CBR with the exception of two reinforced test sections which were constructed to greater and lesser strengths in order to determine the effect subgrade strength had on the performance of the test sections. The test sections were constructed with an average base course thickness of 10.9 in. with the exception of two controls where the base thickness was intentionally increased to evaluate the effect of base thickness on test section performance. Information from the test sections that were purposely constructed with different subgrade
strength and base course thickness were used to correct any variability in the remaining reinforced test sections. Test sections were trafficked using a 45-kip, 3-axle dump truck. Rut, displacement, strain, and pore-water pressure were monitored during trafficking. Post-trafficking excavations were conducted to evaluate damage to the geosynthetic, base contamination from the subgrade, and strength and deformation of the layers. Longitudinal rut was the primary indicator of performance. Geosynthetic material properties were used in a linear regression analysis to determine which properties best related to performance of the test sections in this study as well as test sections from Phase I. It was determined that the strength and stiffness of the junctions and tensile strength properties in the cross-machine direction correlated well with performance. The woven and nonwoven geotextiles also performed well, but further research is needed to determine which material properties correspond to performance. Additional work is needed to more confidently specify minimum values for geosynthetic material properties associated with good performance in subgrade stabilization applications.