Various laboratory testing methods have been developed to characterize the fatigue response of asphalt concrete mixtures. These test methods attempt to simulate in-service conditions or formulate constitutive models. Experiments such as the four-point beam fatigue test have attempted to simulate in-service conditions. The prediction accuracy of such experiments depends on their effectiveness in simulating actual field conditions such as loading, support, stress state, and environment. Constitutive modeling experiments have aimed at measuring fundamental stress-strain relationships so that rigorous constitutive models can be formulated. The results from these experiments are used as input for field performance prediction algorithms. The uniaxial fatigue test is a promising method in this category because of the constant stress state across the specimen section. A few documents have focused on standard test methods for the uniaxial fatigue test; however, there are no AASHTO or ASTM protocols available that include the healing of asphalt concrete mixtures. The main objective of this study was to report on the development of a uniaxial fatigue test protocol that measures fatigue damage and healing of asphalt concrete mixtures. The documented work includes surrogate studies to identify appropriate sample fabrication procedures, gluing materials and procedures, alignment, machine compliance, type of strain wave shape, and strain-control mode of loading. It was found that the use of a gluing jig and 180-mm compaction height was essential to achieve successful mid-specimen failures. In addition, the sinusoidal strain wave shape and on-specimen strain-controlled mode of loading are appropriate test conditions for fatigue damage and healing characterization of asphalt concrete mixtures.
ASJC Scopus subject areas
- Civil and Structural Engineering
- Mechanical Engineering