<p><p><h2>Project Summary/Scope:</h2>Inadequate materials over weak soil in pavement systems frequently lead to the deterioration of flexible pavement systems. Using a geosynthetic placed over a subgrade is an inexpensive and effective method to stabilize the flexible pavement. A field test was conducted and monitored for the performance of geosynthetic in pavement stabilization. The test section was approximately 150 meters in length.</p><p>Subsurface Conditions: The subgrade material had moisture contents of 24 to 31% and dry densities of 12.3 to 14.0 kN/m³. The average CBR value of the subgrade soil was 5%. The three base course layers had thicknesses of the 10 cm, 15 cm, and 20 cm, respectively. The thickness of the HMA averaged 89 mm. The average bulk specific gravity of the asphalt was 2.25.</p><p>The test section was divided into nine sections, including three with geogrid, three with geotextile, and three non-stabilized control sections. Each test section was 15 meters long. The sections contained different types of geosynthetic and varying thicknesses of the base course layer.</p><p>The base aggregate was pushed over the test section using a front-end loader, bladed over with a motor-grader, and compacted with a vibratory roller. Two HMA layers were placed and compacted, followed by a chip seal layer over the base course.<br><h2>Performance Monitoring:</h2>In the field, nuclear density tests were used to determine the dry density and moisture content of the subgrade soil. More than 200 instruments were installed in the test section. Five types of instruments were used, including earth-pressure cells, strain gages, temperature sensors, soil-moisture sensors, and piezoelectric polymer traffic sensors.</p><p>Rut depths were recorded each of the three months the roadway was in service. Rut depth measurements showed improvement in the geosynthetic-stabilized sections. The resilient modulus of the subgrade was back-calculated showing significant increases of subgrade modulus in the geotextile-stabilized sections.<br><h2>Project Technical Paper:</h2>Al-Qadi, I.L., Brandon, T.L. and Bhutta, S.A. (1996). “Field Evaluation of Geosynthetically Stabilized Pavements.” Proceedings of the Fourth Materials Engineering Conference, November, Washington, D.C. 328-337.<br><h2>Date Case History Prepared:</h2><strong> </strong>November 2012</p></p>