Expansive clay subgrades have been the primary cause of damage to many Texas roadways. To mitigate this damage, the Texas Department of Transportation (TxDOT) has used geosynthetics to stabilize the base course of such roadways. However, suitability of this practice has not been fully evaluated. This paper presents an evaluation of the long-term performance of three Texas roadways founded on expansive clay subgrades. Geosynthetic-stabilized test sections and control (non-stabilized) test sections were constructed along the three identified roadways. Long-term performance of the test sections under traffic and environmental loads (induced by swelling and shrinkage of expansive clay subgrades) was evaluated using performance data collected as part of an annual performance monitoring program under TxDOT Performance Management System (PMS). Specifically, three performance measures including the condition score, the percentage of the longitudinal cracks, and the percentage of the total length of rut were used in the evaluation. Significant benefits were found for geosynthetic stabilization in all the three roadways. Benefits included enhanced overall condition and ride quality of the road under traffic and environmental loads as well as reduced percentage of longitudinal cracks. Two improvement factors (IFs), including Condition Score IF and Longitudinal Cracks IF, were defined to compare improvement from geosynthetic stabilization among various roadways. Evaluation of Longitudinal Cracks IF values indicated that the geosynthetic stabilization reduced the percentage of the longitudinal cracks by 70 to 95 %. On the other hand, evaluation of the Condition Score IF values showed that the geosynthetic stabilization increased the condition scores by 25 to 45 %. Utilizing information from PMS databases to evaluate benefits from geosynthetic stabilization introduces a suitable evaluation approach that can conveniently be adopted by researchers and practitioners. This approach is particularly useful for performance evaluation of long and/or high-traffic test sections for which other approaches for collection of performance data may not be practical. The evaluation presented in this paper also highlights the significance of collecting systematic performance data by transportation agencies to provide objective information to support important decisions on rehabilitation projects.
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