The objective of this research is to characterize HMA properties, and to develop phenomenological fatigue relationships for these mixes based on various levels of strain, asphalt content, air voids content, and temperatures on superpave mixes in use in NC. The research will include laboratory investigation of 12.5mm and 19mm intermediate mixes at moderate temperatures of 15° C, 20° C, and 25° C where predominant fatigue cracking is expected to be significant. The principal work tasks to be conducted are as follows:Design asphalt mixes using superpave methodology using PG 64-22 binder.Prepare beam, prismatic beam, and slab specimens and obtain cores.Conduct flexural fatigue tests on beam specimens.Conduct shear frequency sweep tests on cores.Conduct axial frequency sweep tests on prismatic beam specimens.Develop fatigue distress models and axial & shear stiffness models.Develop a pavement and overlay design procedure based on typical pavement cross-sections encountered in NC. This design procedure will account for the AC mix characteristics and the reliability associated with design traffic estimation and material characterization.
The anticipated results of this research along with existing computer models will help NCDOT Engineers to predict pavement failure rates and compare with results of current design procedures to develop a better understanding of the relationship of material properties to fatigue life. A detailed outline of the design procedure will be developed through this research for new pavement design, design of overlays, for forensic analysis of premature failure and for non-compliance of job specification.
