STATE-OF-THE-ART: UNBOUND BASE PERFORMANCE

摘要

Factors affecting the performance of aggregate bases are considered. Aggregate base/subbase performance (as measured by rutting resistance) is primarily related to aggregate shear strength; not "resilient modulus" as utilized in the AASHTO Guide. The AASHTO flexible pavement design procedure has serious inadequacies. The AASHTO "Layer Coefficient-Resilient Modulus/Structural Number" approach is not valid for CFP design. The most effective use of granular base/subbase in CFP construction can be achieved by employing Mechanistic-Empirical (M-E) pavement design concepts. Current technology is adequate to support CFP M-E design procedures. A more fatigue resistant, thus thinner, AC surface would probably require increased aggregate base/subbase thicknesses. Higher quality aggregate base (shear strength/rutting resistance) may be needed. Aggregate base/subbase evaluation should include appropriate/sufficient testing (repeated load triaxial and perhaps rapid shear) to characterize shear strength/rutting potential. Stabilized subgrades can considerably improve CFP performance. Stabilized subgrades facilitate aggregate layer placement/ compaction and provide better confinement (increased aggregate modulus and shear strength) in the aggregate layers.