Effects of Laboratory Compacted Asphalt Mixtures Air-Void Variations on Fracture Properties at Low Temperatures

Asphalt mixtures contain several constituents, among which air void content has a significant effect on pavement performance. In this research, the impact of laboratory compaction air-void variations for asphalt mixtures was investigated on asphalt-mixture fracture energy and peak load, as two primary outcomes of the disk-shaped compact tension test. Two groups of asphalt mixtures with air void contents of 7 +/- 1.0 % were selected, and comprehensive statistical analyses, such as Pearson's correlation coefficient, analysis of variance (ANOVA), Welch's test, and Tukey's test, were conducted to explore any possible impacts of specimen-to-specimen airvoid variation on fracture energy and peak load. Statistical analyses have been carried out on individual asphalt mixtures in groups and all asphalt mixtures together as a group, as well. Results showed that there is a weak-to-negligible relationship between air void, fracture energy, and peak load. In addition, results of the ANOVA at the significance level of 0.05 revealed that air void content does not have any significant effect on asphalt mixtures' fracture energy and peak load, except for peak load data when all asphalt mixtures are grouped as single population. Finally, results of Tukey's test demonstrated that in a range of 7 +/- 1.0 %, air void does not have a significant effect on fracture energy at the significance level of 0.05. The findings of this study can help researchers and agencies extend the air-void variation tolerance to 1 % in asphalt mixtures with target of 7 % air void content to assess low temperature cracking resistance.