This study investigated the validity of various monotonic cracking performance assessment testing standards and indicators to describe the expected cracking performance in the field. A total number of 17 field test sections with known field cracking performance were selected and evaluated. Field cores were extracted from these sections, and a comprehensive laboratory testing program was carried out. The authors conducted four monotonic testing standards and calculated 11 performance indicators. The study findings showed that there was no direct correlation between the laboratory testing results of monotonic tests and indicators and the observed field cracking performance. The variable air void content and thickness of the extracted field cores are believed to influence the laboratory testing results of monotonic tests and indicators. Therefore, this study proposed an alternative approach to develop performance specifications (thresholds) for monotonic tests and indicators. The thresholds were developed indirectly using a correlation between cyclic testing and both monotonic tests and the observed field cracking performance. The results demonstrated the effectiveness and success of the proposed approach in developing performance thresholds. Pass/fail cracking performance assessment thresholds were proposed for various monotonic indicators to distinguish between asphalt mixes with good, fair, and poor cracking resistance. Besides, the study recommends the Weibull cracking resistance index, determined from the indirect tension test, as a simple performance indicator to assess mixes resistance to cracking.
Various monotonic cracking resistance assessment tests and indicators of asphalt mixes have their own merits; however, they provide illogical interpretations of mix resistance to cracking under different air void (AV) contents. This study aims to investigate and address the limitations of the monotonic tests and indicators in evaluating the cracking resistance of asphalt mixes with different AV contents. The results show that the shape of the load-displacement curve, curve basic elements, and monotonic indicators are significantly sensitive to variation in AV content. However, the currently proposed correction ratios could not address this dependency of cracking assessment on AV content. This study therefore proposes and evaluates a new approach and correction ratios for monotonic tests and performance indicators. The results demonstrate that the newly proposed correction ratios could normalize the effect of AV content on the examined performance assessment indicators.
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