Construction and instrumentation of geosynthetically stabilized secondary road test sections

Nine instrumented flexible pavement test sections were constructed in a rural secondary road in southwest Virginia. The nine test sections, each 15 m (50 ft) long, were built to examine the effects of geogrid and geotextile stabilization. Three test sections were constructed with a geogrid, three were built with a geotextile, and three were nonstabilized. The test section base course thicknesses ranged from 10.2 cm (4.0 in.) to 20.3 cm (8.0 in.), and the hot-mix asphalt (HMA) thickness averaged 8.9 cm (3.5 in.). Geosynthetic stabilization was placed on top of the subgrade layer. The pavement test sections were heavily instrumented with two types of pressure cells, soil and HMA strain gauges, thermocouples, and soil moisture cells. In addition, strain gauges were iastalled directly on the geogrid and geotextile An extensive instrumentation infrastructure was constructed to locate all instrumentation, cabling, and data acquisition facilities underground. Instrument survivability has ranged from 6 percent for the strain gauges mounted on the geotextile to 100 percent for the soil moisture blocks after 8 months of operation. The majority of instrument failures occurred either during construction or the first few weeks of operation. The data acquisition system is triggered by traffic passing over piezoelectric sensors and operates remotely. The corresponding data are transferred via modem to Virginia Polytechnic Institute and State University for processing. It is planned that the performance of the pavement test sections will be monitored for a minimum of 3 years.