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Cracking in asphalt concrete (AC) layers is among the driving modes of flexible pavement deterioration. Material properties, along with structural layer characteristics and external factors such as vehicular and environmental loading, govern cracking mechanisms in flexible pavements. Current practice of AC and pavement structural design methods does not allow for direct characterisation of AC impact on crack damage initiation and propagation. Asphalt concrete performance tests are the essential components of performance-related and performance-based specifications, for which they can be used either for screening AC to minimise deterioration risks or to directly predict specific modes of pavement deterioration. This paper evaluates commonly used performance tests intended to characterise AC fracture resistance. A multistep evaluation protocol was applied using various statistical techniques to determine the discrimination ability of each test method outcome criterion as well as strength of correlation to field performance. The results from full-scale accelerated pavement test (APT) sections were used to correlate with the results obtained from various laboratory performance tests. Mixes used in the study contained various levels of reclaimed asphalt pavement and recycled asphalt shingles with a recycled binder ratio up to 40%. It was shown that the flexibility index parameter obtained from the Illinois semi-circular bending (IL-SCB) test, also referred to as the Illinois Flexibility Index Test (I-FIT), resulted in the highest number of subsets and consistent ranking with APT field performance, indicating a high discrimination potential. Even though two of the overlay test's criteria resulted in fewer subsets, they also provided a consistent ranking with APT field performance. Composite scores indicate that the overlay test criteria and flexibility index from the I-FIT had the highest strength of correlation to field performance. [ABSTRACT FROM AUTHOR]

The viscoelastic continuum damage (VECD) theory has been gaining wide acceptance throughout the world as a promising method for characterisation of fatigue cracking susceptibility of asphalt mixtures. This method is also being explored by different countries (e.g. Brazil) to be a part of pavement design and to be used as a component of performance-related specifications. While the VECD is a novel methodology, over the past 20 years, different versions of the formulations have been developed by various researchers. This paper includes history and the basic principles the most common VECD methodologies used today. A thorough review of the formulations as well as the main assumptions of different VECD models is given. In addition, a step-by-step guidance on calibration of VECD model and potential problems related to VECD modelling are presented. Finally, uniaxial tension-compression fatigue test results of six different mixtures (with varying binder PGs, recycled asphalt pavement contents and aggregate gradations) were analysed using three most common VECD formulations. The damage characteristic curves (i.e. C vs. S curves) produced by the different VECD methods as well as predicted number of cycles to failure (Nf) were compared and analysed. [ABSTRACT FROM AUTHOR]