Factors Influencing Deformations of Geocell-Reinforced Recycled Asphalt Pavement Bases under Cyclic Loading

摘要

A significant amount of recycled asphalt pavement (RAP) material is produced from flexible pavement rehabilitation projects. RAP can be used as a base course material for sustainable pavement construction. Performance of a pavement largely depends on the strength of its foundation, which consists of the subgrade and base course layers. Geocell was used in this study to increase the strength of RAP bases. Nine large-scale laboratory cyclic plate loading tests were conducted on unreinforced and geocell-reinforced RAP bases with three different thicknesses (150, 230, and 300 mm) over weak and moderate subgrades to investigate the influence of geocell confinement, base course thickness, base course strength, and subgrade strength on permanent and resilient deformations of RAP bases. The subgrade was prepared by mixing Kansas River sand with kaolin and compacted at weak [target California bearing ratio (CBR) = 2%] and moderate (target CBR = 5%) strengths. The test results showed that geocell confinement improved the performance of reinforced RAP bases by reducing permanent surface deformations and increasing resilient deformations and percentages of resilient deformation as compared with those of unreinforced bases. The RAP bases over the moderate subgrade performed better than those over the weak subgrade. Subgrade strength had a more pronounced effect than geocell confinement on the properties of RAP bases. Geocell confinement was more beneficial for the bases over the weak subgrade than those over the moderate subgrade. The relative improvement factors (RIFs) of the reinforced bases with respect to the unreinforced bases and the bases over the moderate subgrade with respect to the bases over the weak subgrade ranged from 1.1 to 11.4 and 1.2 to 17.2, respectively. The permanent deformation increased with the number of loading cycles and the RTFs increased with the permanent surface deformation of RAP base sections.