Structural Condition Assessment of Reinforced Base-Course Pavement

In 2011, the New Hampshire Department of Transportation (NHDOT) reconstructed 2 miles of Pickering Road in Rochester. This included building three distinct reinforcement conditions: a geogrid reinforcement within the granular base-course layer and no geotextile separator, a geotextile separator between the subgrade soil and the subbase course, and a geogrid reinforcement within the granular base-course layer with a geotextile separator between the subgrade and the subbase layer. The Cold Regions Research and Engineering Laboratory (CRREL) conducted a series of falling weight deflectometer (FWD) tests to monitor changes in layer moduli as the seasons changed. FWD tests occurred several times throughout the year on selected locations along the reinforced and non-reinforced (southern portion) pavement. Based on the seasonal back-calculated moduli for 2014 and 2015 values, the reinforced geogrid granular base-course layer provided higher moduli than the nonreinforced sections, and it appears that the aggregate layer thickness can be reduced to 33%–42% if the base course is reinforced with a geogrid mesh. This higher stiffness should allow the pavement to withstand many more traffic repetitions before fatigue cracking develops; and the geogrid should minimize the influence on thermal cracking.