Mathematical formulation of HMA crack initiation and crack propagation models based on continuum fracture-mechanics and work-potential theory
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abstract
Fatigue cracking due to fracture damage is one of the major structural distresses prevalent in today's hot-mix asphalt (HMA) pavements. HMA resistance to fracture is governed by two fundamental mechanisms: the number of repetitive load cycles for microcracks to coalesce into macrocracks in a crack initiation process (N i) and the number of repetitive load cycles for macrocrack propagation through the HMA layer thickness in a crack propagation process (N p). To adequately model HMA fracture resistance, the fundamental mechanisms of these two processes must be understood. In this study, mathematical models for computing N i and N p were formulated based on continuum fracture-mechanics, the work potential theory, and pseudo-strain energy and surface energy concepts. Verification and sensitivity analysis of the models based on laboratory test data, with traditional Texas HMA mixes, yielded plausible results. Overall, the formulated models were found to be potentially promising as a fundamental means to quantitatively characterize the fracture and fatigue cracking resistance of HMA mixes. However, validation and calibration of the models with more HMA mixes and field data is strongly recommended.
