Evaluation of Geogrid-Reinforced Base Courses: Pavement Design and Initial Construction Costs Under Varying Conditions

A common type of reinforcement technique known as geosynthetics is used to enhance the performance of asphalt pavements both during initial construction, particularly when the pavement is placed on top of a subgrade with low strength, and during the rehabilitation of severely damaged structures. Normally, the use of geosynthetics is not considered in the design of pavements. Two well-known parameters, the traffic benefit ratio (TBR) and the base-course reduction (BCR) factor, can quantify the performance gain of geosynthetics. In the present study, a theoretical parametric analysis was conducted. Several unreinforced structures were initially designed based on the AASHTO method, considering roads resting over weak subgrades on plain terrain. Different reinforcement levels were assumed, according to the literature, for the base layer, to quantify their impact on pavement thickness changes. In addition, based on indicative unit cost values, a comparison of the initial construction costs of base layers was given, for both unreinforced and reinforced structures, to enable a screening comparison on the use of geosynthetics. Within the adopted assumptions, subgrade strength and aggregate transportation distance emerged as the main factors influencing the relative initial-cost attractiveness of reinforcement.