EVALUATION OF FATIGUE AND PERMANENT DEFORMATION PROPERTIES OF SEVERAL ASPHALT-AGGREGATE FIELD MIXES USING STRATEGIC HIGHWAY RESEARCH PROGRAM A-003A EQUIPMENT

Use of fatigue and permanent shear deformation tests, equipment, and analysis procedures developed by the Strategic Highway Research Program (SHRP) A-003A project, are investigated for their applicability to stone matrix asphalt, recycled asphalt pavement, asphalt-rubber concrete, and large stone gradation as well as conventional asphalt-concrete mixes. Materials were collected in the field and compacted in the laboratory following SHRP A-003A rolling wheel procedures. Mixes were tested for fatigue life and flexural stiffness using controlled-strain equipment. Their permanent shear deformation resistance was evaluated using the repetitive simple shear test-constant height (RSST-CH). Results show that the tests and equipment were sensitive to each of the materials tested, and also confirm engineering expectations. Rut depth predictions were made on the basis of the RSST-CH results and a proposed method for translating the permanent shear strains and load repetitions measured by the test to field rut depths and equivalent single axle loads (ESALs). When the measured ESALs and in situ rut depths were compared with test results, the method proved to be a good predictor, although resulting predictions were often somewhat conservative because mixes in the field had aged. Analysis of fatigue and stiffness data for several hypothetical pavement cross sections applying elastic layer theory showed that ranking of mixes for fatigue life depends on the fatigue curve developed from testing, measured flexural stiffness, and properties of the underlying pavement.