Geogrid Reinforced Pavement Structure in a Cold Region

Test sections were constructed in two portions of Maine Route 9 to investigate the use of geosynthetics for reinforcement and drainage of 300 mm (12 in.) and 600 mm (24 in.) thick subbase courses beneath 150 mm (6-in.) of flexible pavement. Four types of test sections were constructed: geogrid reinforcement, drainage geocomposite, drainage geocomposite with geogrid reinforcement, and control. Test sections using reinforcement geogrid have strain gages attached to the geogrid to measure induced forces. Reinforcement sections have geogrid either on subgrade or in the center of the subbase to evaluate the effects of geogrid location. Drainage geocomposite and control sections have vibrating wire piezometers to monitor porewater pressure in the subgrade and subbase course. Thermocouples were used to measure the depth of frost penetration. This paper deals primarily with seasonal and long-term changes in the geogrid force.