EVALUATION OF GEOGRID-REINFORCED GRANULAR BASE

In the summer of 1995, the Wyoming Department of Transportation constructed a pavement section to evaluate the performance of biaxial geogrid. The experimental pavement consisted of two sections: one with a typical granular base and the other with a thinner granular base with geogrid. The main objectives of the experiment were to evaluate the field performance of geogrid bases and to determine the cost-effectiveness of geogrid materials. Comprehensive field evaluations were performed on the test sections shortly after construction and in 1998. These evaluations included falling weight deflectometer, rut measurements, and pavement condition surveys. The analysis on deflection measurements coupled with approximately equal rutting in the control and geogrid sections indicated that 280 mm (11 in.) of crushed based reinforced with geogrid can adequately replace 430 mm (17 in.) of conventional crushed base. Cost analysis demonstrated that the economic viability of geogrid reinforcement was proportional to the cost of the base material, which was largely controlled by the haul distance. As contractors gain more experience with placing reinforcing geosynthetics, costs should go down, making geogrid reinforcement economically viable in more situations.