Damage evolution in triaxial compression tests of HMA at high temperatures
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The evolution of damage of hot mix asphalt (HMA) at high temperatures were determined using triaxial compression tests. Damage in HMA was found to initiate following a period of microstructure hardening. Damage was localized in a critical section in a specimen that was mainly responsible for failure. The growth and propagation of cracks in this critical section was significantly larger than that in the rest of the specimen. Test specimens exhibited three well-defined regions (top, middle, and bottom) in terms of void and crack distributions. The top part of the specimens exhibited significant cracking, the middle part exhibited significant amount of dilation, and minor microstructural changes occurred in the bottom part. These variations within a specimen were attributed mainly to the heterogeneity of the HMA microstructure. The results of this study would significantly contribute to the understanding of the damage mechanism in HMA at the microstructural level. Damage was a localized phenomenon occurring in a critical section due to the heterogeneity of the microstructure. Therefore, assuming uniform damage distribution would require an unrealistic amount of damage to capture the measured stress-strain relationships. The results would influence the approaches typically followed in the development of permanent deformation models. These models should account for the influence of localized damage on permanent deformation. This is an abstract of a paper presented at the Association of Asphalt Paving Technologists 2004 Technology Sessions (Baton Rouge, LA 3/10-18/2004).