CHARACTERIZATION OF PLASTIC DEFORMATION OF UNBOUND MATERIALS USING ACCELERATED PAVEMENT TESTING (05-2020)
Manuel Bejarano, Tigerbrain Engineering

The elastic and plastic behavior of granular materials and subgrade soils is usually characterized in the laboratory by means of a triaxial apparatus. In the laboratory a sample of undisturbed cohesive soil or compacted aggregate base or subgrade material is subjected to a series of stress paths that intend to simulate the field conditions of vehicle traffic. Laboratory sample and loading conditions are different from those encountered in real pavements. To overcome these differences, non-destructive devices such as the falling weight deflectometer are being used for estimating the in-situ elastic response of materials. The impact loading of a falling weight deflectometer simulates the pass of a vehicle at a speed of 40 mph. Although reasonable elastic response of unbound materials can be obtained from non-destructive testing, little can be said in regards to the plastic behavior. However, instrumented in-service highways can provide valuable information but results would be limited and available after many years depending on instrument reliability. To overcome these limitations, accelerated pavement test facilities can produce significant amount of pavement behavior data under various environmental and loading conditions. Data obtained from these tests can be used to characterize pavement materials under realistic pavement conditions, and/or verify the results of laboratory tests. This paper focuses on a preliminary analysis of the elastic and plastic behavior of an aggregate base, an aggregate subbase, and a cohesive subgrade under accelerated pavement testing.